To see the other types of publications on this topic, follow the link: Stimuli de ler ordre.
Journal articles on the topic 'Stimuli de ler ordre'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Stimuli de ler ordre.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Watenpaugh, Donald E., Gregory A. Breit, Theresa M. Buckley, Richard E. Ballard, Gita Murthy, and Alan R. Hargens. "Human cutaneous vascular responses to whole-body tilting, Gz centrifugation, and LBNP." Journal of Applied Physiology 96, no. 6 (June 2004): 2153–60. http://dx.doi.org/10.1152/japplphysiol.00198.2003.
Full textAbstract:
We hypothesized that gravitational stimuli elicit cardiovascular responses in the following order with gravitational stress equalized at the level of the feet, from lowest to highest response: short-(SAC) and long-arm centrifugation (LAC), tilt, and lower body negative pressure (LBNP). Up to 15 healthy subjects underwent graded application of the four stimuli. Laser-Doppler flowmetry measured regional skin blood flow. At 0.6 Gz (60 mmHg LBNP), tilt and LBNP similarly reduced leg skin blood flow to ∼36% of supine baseline levels. Flow increased back toward baseline levels at 80–100 mmHg LBNP yet remained stable during 0.8–1.0 Gz tilt. Centrifugation usually produced less leg vasoconstriction than tilt or LBNP. Surprisingly, SAC and LAC did not differ significantly. Thigh responses were less definitive than leg responses. No gravitational vasoconstriction occurred in the neck. All conditions except SAC increased heart rate, according to our hypothesized order. LBNP may be a more effective and practical means of simulating cardiovascular effects of gravity than centrifugation.
2
De Paepe, Annick, Valéry Legrain, and Geert Crombez. "Visual stimuli within peripersonal space prioritize pain." Seeing and Perceiving 25 (2012): 88. http://dx.doi.org/10.1163/187847612x647072.
Full textAbstract:
Localizing pain not only requires a simple somatotopic representation of the body, but also knowledge about the limb position (i.e., proprioception), and a visual localization of the pain source in external space. Therefore, nociceptive events are remapped into a multimodal representation of the body and the space nearby (i.e., a peripersonal schema of the body). We investigated the influence of visual cues presented either in peripersonal, or in extrapersonal space on the localization of nociceptive stimuli in a temporal order judgement (TOJ) task. 24 psychology students made TOJs concerning which of two nociceptive stimuli (one applied to each hand) had been presented first (or last). A spatially non-predictive visual cue (i.e., lighting of a LED) preceded (80 ms) the nociceptive stimuli. This cue was presented randomly either on the hand of the participant (in peripersonal space), or 70 cm in front of the hand (in extrapersonal space), and either on the left or on the right side of space. Biases in spatial attention are reflected by the point of subjective simultaneity (PSS). The results revealed that TOJs were more biased towards the visual cue in peripersonal space in comparison with the visual cue in extrapersonal space. This study provides evidence for the crossmodal integration of visual and nociceptive stimuli in a peripersonal schema of the body. Future research with this paradigm will explore crossmodal attention deficits in chronic pain populations.
3
Venini, Dustin, Roger W. Remington, Gernot Horstmann, and Stefanie I. Becker. "Centre-of-Gravity Fixations in Visual Search: When Looking at Nothing Helps to Find Something." Journal of Ophthalmology 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/237812.
Full textAbstract:
In visual search, some fixations are made between stimuli on empty regions, commonly referred to as “centre-of-gravity” fixations (henceforth: COG fixations). Previous studies have shown that observers with task expertise show more COG fixations than novices. This led to the view that COG fixations reflect simultaneous encoding of multiple stimuli, allowing more efficient processing of task-related items. The present study tested whether COG fixations also aid performance in visual search tasks with unfamiliar and abstract stimuli. Moreover, to provide evidence for the multiple-item processing view, we analysed the effects of COG fixations on the number and dwell times of stimulus fixations. The results showed that (1) search efficiency increased with increasing COG fixations even in search for unfamiliar stimuli and in the absence of special higher-order skills, (2) COG fixations reliably reduced the number of stimulus fixations and their dwell times, indicating processing of multiple distractors, and (3) the proportion of COG fixations was dynamically adapted to potential information gain of COG locations. A second experiment showed that COG fixations are diminished when stimulus positions unpredictably vary across trials. Together, the results support the multiple-item processing view, which has important implications for current theories of visual search.
4
Nagahama, S., and K. Kurihara. "Norepinephrine as a possible transmitter involved in synaptic transmission in frog taste organs and Ca dependence of its release." Journal of General Physiology 85, no. 3 (March 1, 1985): 431–42. http://dx.doi.org/10.1085/jgp.85.3.431.
Full textAbstract:
In order to explore the role of catecholamine and Ca2+ in the synaptic transmission from taste cells to sensory nerve terminals, the effects of various agents added to an artificial solution perfusing the lingual artery on the frog taste nerve responses were examined. The injection of reserpine or guanetidine, which are catecholamine-depleting agents, led to a great reduction of the frog taste nerve responses. The addition of catecholamines to the perfusing solution did not practically enhance the spontaneous impulse discharges, but did recover the response to all the taste stimuli examined. Norepinephrine was most effective and is the most likely candidate for the transmitter. The enhancement of the responses by norepinephrine was suppressed by desipramine, cocaine, or imipramine, which suggests that the enhancement was brought about by incorporation of norepinephrine into taste cells. In a previous paper (Nagahama, S., Y. Kobatake, and K. Kurihara, 1982. J. Gen. Physiol. 80:785), we showed that the responses to the stimuli of one group depended on Ca2+, cGMP, and cAMP added to the perfusing solution and those to the stimuli of another group did not depend on these agents. After the injection or addition of reserpine to the lingual artery, which probably modified injection or addition of reserpine to the lingual artery, which probably modified the permeability of the artery, the responses to the stimuli of the latter group also came to exhibit dependences on these agents, which indicates that the responses to all the taste stimuli have dependences on Ca2+, cGMP, and cAMP.
5
Rasmussen, Vibe Maria, Catarina Ellehuus-Hilmersson, Per Rotbøll-Nielsen, and Mads Utke Werner. "Spatial summation of thermal stimuli assessed by a standardized, randomized, single-blinded technique." Scandinavian Journal of Pain 9, no. 1 (October 1, 2015): 81–86. http://dx.doi.org/10.1016/j.sjpain.2014.12.001.
Full textAbstract:
AbstractBackground and aimsQuantitative sensory testing of thermal perception (QTT) is a valuable method in clinical and experimental assessment of the function of small nerve fibres. Previous studies have indicated existence of spatial summation for warmth, cool and heat pain stimulation, but study designs and assessment methods have not always been mutually consistent. The aims of this study were, first, to examine spatial summation of QTT by differently sized contact thermodes, and, second, to evaluate if these differences are significant from a clinical and scientific perspective.MethodsSixteen healthy subjects were included. Warmth detection (WDT), cool detection (CDT) and heat pain (HPT) thresholds were assessed in random order, with the stimulation areas of the contact thermodes of 3.0, 6.3 and 12.5 cm2, blinded to the subjects. Assessments were made bilaterally at volar part of the distal arm and medial part of the lower leg. Data analyses were by a mixed model with random effect for subject and fixed-effects for the variables, site (arm/leg), thermode area (ln thermode area) and side (dominant/non-dominant), in addition to conventional pairwise non-parametric comparisons.ResultsData from 2 subjects were excluded. In the remaining 14 subjects only 4 subjects were able to identify the correct sequence of thermode sizes. The model demonstrated highly statistical significant relationships regarding main effects: thermode area (P < 0.0001) and stimulation site (P < 0.0001; except for CDT P = 0.011). The only significant interaction was between thermode area*site (P = 0.005) for CDT. The study demonstrated in 17 of 18 possible comparisons between thermode size and stimulation site, a significant spatial summation for WDT, CDT and HPT.ConclusionThis randomized, single-blind study of thermal thresholds demonstrated spatial summation and that considerable deviations may occur if values obtained with differing thermode sizes are used uncritically.ImplicationsData from the present study enable interpolation of thermal thresholds with differing thermode sizes, facilitating comparisons across studies.
6
محمد مجاهد, عبد المنعم. "الغضب مفرداته ومثيراته في ضوء النصوص المصرية القديمة (Anger: Its Lexical Meanings and its Motives in the Light of Ancient Egyptian Texts)." Abgadiyat 7, no. 1 (2012): 160–82. http://dx.doi.org/10.1163/22138609-00701013.
Full textAbstract:
The researcher collected about twenty-one words in Ancient Egyptian language, each of them meaning anger; as well as many derivations of these words through sign commutation, sign germination, and sign additions (such as causatives; of the infinitive). Specific words may also be added some of these lexical meanings to form expressions denoting to anger and its responses simultaneously. The researcher noted that some of these words expressed the meaning of anger contextually, not lexically, due to the connection between its lexical meanings and emotional responses of anger. The emotion stimuli of anger, or stressful events that led to it, combined in Ancient Egypt, stimuli related to the abuse and harm to the angry, materially and morally (such as honor violation, assault and battery, losing wishes, difference of opinion; and may be also as a result of the other‘s misconduct, the misconduct toward the ruler and the country‘s security). Obviously, this latter type of stimuli associated with the king personality (such as his anger concerning triumph delay, contumacy toward him and his country, as well as threaten its security). The ancient Egyptian noted, through experience, that anger of the Warrior King had an impact in achieving victory; it is an effect that was proven by modern psychology; this led the ancient Egyptian to connect permanently between the anger emotion of the king and his military activities. So the desire to winning represented permanent stimuli, tempted the royal anger through wars. This is known in modern psychology “Behavioral Reactions”, that is if anger achieved a positive result for an individual, it would be an encouragement for an individual to use it in similar situations afterward. Finally, we have another type of anger stimuli associated with the deceased; it is his expectations to be exposed in the afterlife by forms of abuse and harm that would prevent him from obtaining what he wishes. The researcher divided his study into two parts, tracked in the first the lexical meanings denoting anger in ancient Egyptian language, according to its order in the ancient Egyptian dictionaries. The second part discussed the anger stimuli in light of the ancient Egyptian texts. The last part has three topics, guided by modern psychology, the first is entitled “The Conditions and External Factors”; the second is “The Reactions Behavioral”; and the last topic is “The Expectations”. (Please note that this article is in Arabic)
7
Temme, J. Elbert V., and Carline A. C. Gieszen. "Contrast Effects and Social Desirability in Art Appreciation." Empirical Studies of the Arts 13, no. 2 (July 1995): 171–81. http://dx.doi.org/10.2190/7eha-jdc4-uvbj-h1rv.
Full textAbstract:
In a number of experiments the effects of presenting different categories of art in contrasting order were explored. In the first experiment traditional and abstract paintings and Chinese calligraphy were used as stimuli, each type was contrasted with the other two, which led to shifts in appreciation as well as in perceived complexity. Two more experiments were performed. In one of these experiments fragments of traditional and modern classical music were presented. The same effect was found as when traditional and abstract paintings were contrasted: enhancement of the appreciation of traditional music but no decrease in the appreciation of modern music. It seems that when art is concerned only positive contrast effects are obtained. A possible explanation could be that it is considered socially undesirable to admit a lesser appreciation of modern than of traditional art. To test this hypothesis, socially ‘neutral’ stimuli, Chinese ideographs, differing in aesthetic quality, were contrasted. This yielded the expected positive as well as negative effects.
8
Behroozi, Mehdi, Brendon K. Billings, Xavier Helluy, Paul R. Manger, Onur Güntürkün, and Felix Ströckens. "Functional MRI in the Nile crocodile: a new avenue for evolutionary neurobiology." Proceedings of the Royal Society B: Biological Sciences 285, no. 1877 (April 25, 2018): 20180178. http://dx.doi.org/10.1098/rspb.2018.0178.
Full textAbstract:
Crocodilians are important for understanding the evolutionary history of amniote neural systems as they are the nearest extant relatives of modern birds and share a stem amniote ancestor with mammals. Although the crocodilian brain has been investigated anatomically, functional studies are rare. Here, we employed functional magnetic resonance imaging (fMRI), never tested in poikilotherms, to investigate crocodilian telencephalic sensory processing. Juvenile Crocodylus niloticus were placed in a 7 T MRI scanner to record blood oxygenation level-dependent (BOLD) signal changes during the presentation of visual and auditory stimuli. Visual stimulation increased BOLD signals in rostral to mid-caudal portions of the dorso-lateral anterior dorsal ventricular ridge (ADVR). Simple auditory stimuli led to signal increase in the rostromedial and caudocentral ADVR. These activation patterns are in line with previously described projection fields of diencephalic sensory fibres. Furthermore, complex auditory stimuli activated additional regions of the caudomedial ADVR. The recruitment of these additional, presumably higher-order, sensory areas reflects observations made in birds and mammals. Our results indicate that structural and functional aspects of sensory processing have been likely conserved during the evolution of sauropsids. In addition, our study shows that fMRI can be used to investigate neural processing in poikilotherms, providing a new avenue for neurobiological research in these critical species.
9
Bondarko, V. M., and M. V. Danilova. "Separation Discrimination in the Presence of Flanking Lines." Perception 26, no. 1_suppl (August 1997): 92. http://dx.doi.org/10.1068/v970214.
Full textAbstract:
The presence of flanking stimuli decreases sensitivity in many visual tasks. Earlier we showed that size perception depends on the distance between objects (Bondarko and Danilova, 1996 Perception25 Supplement, 94). Now we suggest that flanks not only decrease sensitivity, but also lead to misperception of size. To test this hypothesis we studied the perception of spatial interval for a set of separations from 6 to 33 min−1 in the presence of two vertical flanking lines. The method of constant stimuli was used in a temporal 2AFC paradigm. Reference stimuli were two vertical lines with separation S, either with or without two symmetrical external flanking lines. The distance to the flanking lines varied from 1/4 S to 3 S in steps of 1/4 S. The test stimuli were just two lines. The first stimulus in the pair could be either the test or the reference. Observers had to report whether the distance between the two central lines in the first stimulus were smaller or larger than the distance in the second stimulus. Probit analysis was used to estimate the threshold and the point of subjective equality (PSE). We found that the PSE implied overestimation by up to 10% of the spatial intervals for the smallest distances to the flanking lines. Increasing distances to the flanking lines finally led to slight underestimation. The strength of the illusion depended on the order of presentation of the reference and test stimuli. Thresholds increased for the smallest distances to flanking lines. Our results confirmed the hypothesis that flanks can induce distortions in size perception. We suggest that our experimental situation could be considered as a one-dimensional case of geometrical visual illusions such as the Ebbinghaus illusion.
10
Lalor, Edmund C., Alan J. Power, Richard B. Reilly, and John J. Foxe. "Resolving Precise Temporal Processing Properties of the Auditory System Using Continuous Stimuli." Journal of Neurophysiology 102, no. 1 (July 2009): 349–59. http://dx.doi.org/10.1152/jn.90896.2008.
Full textAbstract:
In natural environments complex and continuous auditory stimulation is virtually ubiquitous. The human auditory system has evolved to efficiently process an infinitude of everyday sounds, which range from short, simple bursts of noise to signals with a much higher order of information such as speech. Investigation of temporal processing in this system using the event-related potential (ERP) technique has led to great advances in our knowledge. However, this method is restricted by the need to present simple, discrete, repeated stimuli to obtain a useful response. Alternatively the continuous auditory steady-state response is used, although this method reduces the evoked response to its fundamental frequency component at the expense of useful information on the timing of response transmission through the auditory system. In this report, we describe a method for eliciting a novel ERP, which circumvents these limitations, known as the AESPA (auditory-evoked spread spectrum analysis). This method uses rapid amplitude modulation of audio carrier signals to estimate the impulse response of the auditory system. We show AESPA responses with high signal-to-noise ratios obtained using two types of carrier wave: a 1-kHz tone and broadband noise. To characterize these responses, they are compared with auditory-evoked potentials elicited using standard techniques. A number of similarities and differences between the responses are noted and these are discussed in light of the differing stimulation and analysis methods used. Data are presented that demonstrate the generalizability of the AESPA method and a number of applications are proposed.
11
Hermida Cadena, Luis Fernando, Antonio Carlos Lobo Soares, Ignacio Pavón, and Luis Bento Coelho. "Assessing soundscape: Comparison between in situ and laboratory methodologies." Noise Mapping 4, no. 1 (March 28, 2017): 57–66. http://dx.doi.org/10.1515/noise-2017-0004.
Full textAbstract:
AbstractThe assessment of soundscape implies an interdisciplinary approach, where objective and subjective aspects are considered. For the subjective evaluation, in situ and laboratory methodologies are usually followed. Local observations allow the collection of information on the influence of different stimuli present in the environment, whereas laboratory tests present a determined quantity of controlled stimuli to the evaluator. The purpose of this work is to compare results from the different methodologies in order to understand their strengths and their weaknesses. Three urban parks in the city of Lisbon, Portugal, were evaluated. Fragments of binaural sound recordings collected in the parks were used in laboratory tests to compare with the responses in situ and of expert and nonexpert listeners. Statistically significant differences were found in several of the perceptual attributes under observation, which led to variation in the results of the main model’s components. The sound environments were found to be more pleasant and uneventful in situ than in the laboratory, a phenomenon possibly due to the influence of other stimuli such as visual in the process of assessment. The in situ tests allow a systemic and holistic evaluation of the environment under study,whereas the laboratory tests allow a specific and tightly targeted analysis of different component sound events. Therefore, the two methodologies can be useful in soundscape assessment depending on the specific application and needs. No differences were found in the assessment made by either experts or nonexperts.
12
Stewart, Julian M., Carol Karman, Leslie D. Montgomery, and Kenneth J. McLeod. "Plantar vibration improves leg fluid flow in perimenopausal women." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 288, no. 3 (March 2005): R623—R629. http://dx.doi.org/10.1152/ajpregu.00513.2004.
Full textAbstract:
Recent studies have indicated that plantar-based vibration may be an effective approach for the prevention and treatment of osteoporosis. We addressed the hypothesis of whether the plantar vibration operated by way of the skeletal muscle pump, resulting in enhanced blood and fluid flow to the lower body. We combined plantar stimulation with upright tilt table testing in 18 women aged 46–63 yr. We used strain-gauge plethysmography to measure calf blood flow, venous capacitance, and the microvascular filtration relation, as well as impedance plethysmography to examine changes in leg, splanchnic, and thoracic blood flow while supine at a 35° upright tilt. A vibrating platform was placed on the footboard of a tilt table, and measurements were made at 0, 15, and 45 Hz with an amplitude of 0.2 g point to point, presented in random order. Impedance-measured supine blood flows were significantly ( P = 0.05) increased in the calf (30%), pelvic (26%), and thoracic regions (20%) by plantar vibration at 45 Hz. Moreover, the 25–35% decreases in calf and pelvic blood flows associated with upright tilt were reversed by plantar vibration, and the decrease in thoracic blood flow was significantly attenuated. Strain-gauge measurements showed an attenuation of upright calf blood flow. In addition, the microvascular filtration relation was shifted with vibration, producing a pronounced increase in the threshold for edema, Pi, due to enhanced lymphatic flow. Supine values for Pi increased from 24 ± 2 mmHg at 0 Hz to 27 ± 3 mmHg at 15 Hz, and finally to 31 ± 2 mmHg at 45 Hz ( P < 0.01). Upright values for Pi increased from 25 ± 3 mmHg at 0 Hz, to 28 ± 4 mmHg at 15 Hz, and finally to 35 ± 4 mmHg at 45 Hz. The results suggest that plantar vibration serves to significantly enhance peripheral and systemic blood flow, peripheral lymphatic flow, and venous drainage, which may account for the apparent ability of such stimuli to influence bone mass.
13
Oono, Yuka, Hongling Nie, Renata Lima Matos, Kelun Wang, and Lars Arendt-Nielsen. "The inter- and intra-individual variance in descending pain modulation evoked by different conditioning stimuli in healthy men." Scandinavian Journal of Pain 2, no. 4 (October 1, 2011): 162–69. http://dx.doi.org/10.1016/j.sjpain.2011.05.006.
Full textAbstract:
AbstractBackground and purposeConditioned pain modulation (CPM) is a phenomenon in which pain is inhibited by heterotopic noxious stimulation. It is not known how the experimental condition affects the magnitude of the CPM response and the inter-and intra-individual variations. It is important to get the information of the test–retest reliability and inter–individual variations of CPM to apply CPM as a diagnostic tool or for screening analgesic compounds. This study evaluated (1) the magnitude of CPM, (2) the inter-individual coefficient of variation (inter-CV) and (3) the intra-individual coefficient of variation (intra-CV) to (A) different stimulus modalities to evoke CPM and (B) different assessment sites.MethodsTwelve healthy men (age 19–38 years) participated in this study. Cold pressor pain (CPP) (immersing the hand into cold water), tourniquet pain (cuff around the upper arm) and mechanical pressure pain (craniofacial region) were used in randomized order as conditioning stimuli (CS). The test stimulus (TS) was pressure pain applied to the right masseter muscle, left forearm and leg (bilateral tibialis anterior: TA). The responses were pressure pain thresholds (PPT), pressure pain tolerance (PPTol) thresholds and the pain intensity which was assessed on a visual analogue scale (VAS, 0–10 cm) following 1.4 and 1.6 × PPT applied to TA. The TS was applied before, during and 10 min after the CS. The intra-individual CV was estimated between different days.ResultsCPP induced the most powerful CPM on PPT (66.3 ± 10.0% increase), VAS ratings (41.5 ± 5.3% reduction) and PPTol (32.6±4.6% increase), especially at TA, and resulted in the smallest inter-CV (41.4–60.1%). Independently of the CS, the inter-CV in general showed that the recordings from the orofacial region and the forearm had smaller values than from the leg. The smallest intra-CV value was obtained in pain ratings with CPP (27.0%).ConclusionsThis study suggests that (1) the CPP evokes the largest CPM, (2) the leg as the assessment site results in the largest CPM responses and (3) the CPP causes the smallest inter- and intra-CV.ImplicationThe present investigation implicates that the CPP is the most efficient conditioning stimulus to induce CPM when assessed by pressure pain thresholds.
14
Pechauer, Alex D., David Huang, and Yali Jia. "Detecting Blood Flow Response to Stimulation of the Human Eye." BioMed Research International 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/121973.
Full textAbstract:
Retinal blood supply is tightly regulated under a variety of hemodynamic considerations in order to satisfy a high metabolic need and maintain both vessel structure and function. Simulation of the human eye can induce hemodynamics alterations, and attempt to assess the vascular reactivity response has been well documented in the scientific literature. Advancements in noninvasive imaging technologies have led to the characterization of magnitude and time course in retinal blood flow response to stimuli. This allowed for a better understanding of the mechanism in which blood flow is regulated, as well as identifying functional impairments in the diseased eye. Clinically, the ability to detect retinal blood flow reactivity during stimulation of the eye offers potential for the detection, differentiation, and diagnosis of diseases.
15
Grafton, S. T., A. H. Fagg, and M. A. Arbib. "Dorsal Premotor Cortex and Conditional Movement Selection: A PET Functional Mapping Study." Journal of Neurophysiology 79, no. 2 (February 1, 1998): 1092–97. http://dx.doi.org/10.1152/jn.1998.79.2.1092.
Full textAbstract:
Grafton, S. T., A. H. Fagg, and M. A. Arbib. Dorsal premotor cortex and conditional movement selection: a PET functional mapping study. J. Neurophysiol. 79: 1092–1097, 1998. Positron emission tomography (PET) brain mapping was used to investigate whether or not human dorsal premotor cortex is involved in selecting motor acts based on arbitrary visual stimuli. Normal subjects performed four movement selection tasks. A manipulandum with three graspable stations was used. An imperative visual cue (LEDs illuminated in random order) indicated which station to grasp next with no instructional delay period. In a power task, a large aperture power grip was used for all trials, irrespective of the LED color. In a precision task, a pincer grasp of thumb and index finger was used. In a conditional task, the type of grasp (power or precision) was randomly determined by LED color. Comparison of the conditional selection task versus the average of the power and precision tasks revealed increased blood flow in left dorsal premotor cortex and superior parietal lobule. The average rate of producing the different grasp types and transport to the manipulandum stations was equivalent across this comparison, minimizing the contribution of movement attributes such as planning the individual movements (as distinct from planning associated with use of instructional stimuli), kinematics, or direction of target or limb movement. A comparison of all three movement tasks versus a rest task identified movement related activity involving a large area of central, precentral and postcentral cortex. In the region of the precentral sulcus movement related activity was located immediately caudal to the area activated during selection. The results establish a role for human dorsal premotor cortex and superior parietal cortex in selecting stimulus guided movements and suggest functional segregation within dorsal premotor cortex.
16
Smith, Vivianne C., Joel Pokorny, Barry B. Lee, and Dennis M. Dacey. "Primate Horizontal Cell Dynamics: An Analysis of Sensitivity Regulation in the Outer Retina." Journal of Neurophysiology 85, no. 2 (February 1, 2001): 545–58. http://dx.doi.org/10.1152/jn.2001.85.2.545.
Full textAbstract:
The human cone visual system maintains sensitivity over a broad range of illumination, from below 1 troland to 1,000,000 trolands. While the cone photoreceptors themselves are an important locus for sensitivity regulation—or light adaptation—the degree to which they contribute in primates remains unclear. To determine the range of sensitivity regulation in the outer retina, the temporal dynamics, neural gain control, and response range compression were measured in second-order neurons, the H1 horizontal cells, of the macaque retina. Situated at the first synapse in the retina, H1 cells receive input from a large population of cones. Lee et al. have previously shown that sensitivity regulation in H1 cells is both cone type-specific and spatially restricted. The sensitivity regulation seen in H1 cells at moderate illuminances thus takes place before the summation of cone signals in these cells, and the data establish the H1 cell as a convenient locus for analyzing cone signals. In the present study, cone-driven responses of primate H1 cells to temporally modulated sine-wave stimuli and to increment pulses were measured at steady levels of 1–1,000 trolands. The H1 cell gave a modulated response to sine-wave stimuli and hyperpolarized to increment pulses with overshoots at stimulus onset and offset. The temporal amplitude sensitivity function was primarily low-pass in shape, with a small degree of low-frequency roll off and a resonance shoulder near 40 Hz. A model incorporating a cascade of first-order filters together with an underdamped second-order filter could describe both temporal sinusoidal and pulse hyperpolarizations. Amplitude sensitivity was estimated from both pulse and sine-wave data as a function of the steady adaptation level. Sensitivity at low light levels (1 troland) showed a slowing in temporal dynamics, indicating time-dependent sensitivity regulation. Sensitivity was reduced at light levels above approximately 10 trolands, reflecting both response range compression and neural gain control. Thus the outer retina is a major locus for sensitivity regulation in primates.
17
Sugathan, Manju, and Martin Douglas Hendry. "Market Forecasts and Personal Adoption of Smart Textiles in Fitness Sector." International Journal of Technology Diffusion 8, no. 3 (July 2017): 57–75. http://dx.doi.org/10.4018/ijtd.2017070104.
Full textAbstract:
The basic concept of smart textiles consists of textile structures that can sense and react to different stimuli from their environment. While forecasts indicate how this sector has the potential to grow in the future, a gap remains for smart textiles to become commercially viable. Growth in consumerism and consumption of services and experiences has led to innovative products that satisfy higher order needs including ideas, sensory and emotional fulfilment, cultural experiences and entertainment. The aim of the paper is to understand smart textiles in this context and to identify factors that influence personal ownership in fitness sector. These will help manufacturers and technologists gain insight into consumer experience and contribute to better design, innovation, marketing and services. The research findings identify important features consumers value in their decision making to purchase a smart top in fitness sector. The results contribute to the field of user adoption in smart textiles and conclude with proposals for the direction of future design and technical development.
18
Seeber, Andrew, Michael H. Hauer, and Susan M. Gasser. "Chromosome Dynamics in Response to DNA Damage." Annual Review of Genetics 52, no. 1 (November 23, 2018): 295–319. http://dx.doi.org/10.1146/annurev-genet-120417-031334.
Full textAbstract:
Recent advances in both the technologies used to measure chromatin movement and the biophysical analysis used to model them have yielded a fuller understanding of chromatin dynamics and the polymer structure that underlies it. Changes in nucleosome packing, checkpoint kinase activation, the cell cycle, chromosomal tethers, and external forces acting on nuclei in response to external and internal stimuli can alter the basal mobility of DNA in interphase nuclei of yeast or mammalian cells. Although chromatin movement is assumed to be necessary for many DNA-based processes, including gene activation by distal enhancer–promoter interaction or sequence-based homology searches during double-strand break repair, experimental evidence supporting an essential role in these activities is sparse. Nonetheless, high-resolution tracking of chromatin dynamics has led to instructive models of the higher-order folding and flexibility of the chromatin polymer. Key regulators of chromatin motion in physiological conditions or after damage induction are reviewed here.
19
Massot, Corentin, Maurice J. Chacron, and Kathleen E. Cullen. "Information transmission and detection thresholds in the vestibular nuclei: single neurons vs. population encoding." Journal of Neurophysiology 105, no. 4 (April 2011): 1798–814. http://dx.doi.org/10.1152/jn.00910.2010.
Full textAbstract:
Understanding how sensory neurons transmit information about relevant stimuli remains a major goal in neuroscience. Of particular relevance are the roles of neural variability and spike timing in neural coding. Peripheral vestibular afferents display differential variability that is correlated with the importance of spike timing; regular afferents display little variability and use a timing code to transmit information about sensory input. Irregular afferents, conversely, display greater variability and instead use a rate code. We studied how central neurons within the vestibular nuclei integrate information from both afferent classes by recording from a group of neurons termed vestibular only (VO) that are known to make contributions to vestibulospinal reflexes and project to higher-order centers. We found that, although individual central neurons had sensitivities that were greater than or equal to those of individual afferents, they transmitted less information. In addition, their velocity detection thresholds were significantly greater than those of individual afferents. This is because VO neurons display greater variability, which is detrimental to information transmission and signal detection. Combining activities from multiple VO neurons increased information transmission. However, the information rates were still much lower than those of equivalent afferent populations. Furthermore, combining responses from multiple VO neurons led to lower velocity detection threshold values approaching those measured from behavior (∼2.5 vs. 0.5–1°/s). Our results suggest that the detailed time course of vestibular stimuli encoded by afferents is not transmitted by VO neurons. Instead, they suggest that higher vestibular pathways must integrate information from central vestibular neuron populations to give rise to behaviorally observed detection thresholds.
20
Reifsnider, Eric S., and Daniel Tranchina. "Background contrast modulates kinetics and lateral spread of responses to superimposed stimuli in outer retina." Visual Neuroscience 12, no. 6 (November 1995): 1105–26. http://dx.doi.org/10.1017/s0952523800006751.
Full textAbstract:
AbstractSurround enhancement (sensitization) is a poorly understood form of network adaptation in which the kinetics of the responses of retinal neurons to test stimuli become faster, and absolute sensitivity of the responses increases with increasing level of steady, surrounding light. Surround enhancement has been observed in all classes of retinal neurons in lower vertebrates except cones, in some primate retinal ganglion cells, and in human psychophysical studies. In theory, surround enhancement could be mediated by two broad classes of mechanisms, which are not mutually exclusive: one in which the kinetics of the transduction linking cone voltage to postsynaptic current in second-order neurons is modulated, and another in which the transformation of postsynaptic current to membrane voltage is modulated. We report here that both classes of mechanism play a role in surround enhancement measured in turtle horizontal cells (HCs). We stimulated the retina by modulating sinusoidally the illuminance of a bar placed at various positions in the HC receptive field. The bar was surrounded by either equally luminant or dim, steady light. Interpretation of responses in the context of a model for the cone-HC network led to the conclusion that the speeding up of response kinetics —due to selective increase in response gain at high temporal frequencies — by surround illuminance is almost completely accounted for by the change in the kinetics of the transduction linking cone membrane potential to HC postsynaptic current. However, surround illuminance also had an additional, surprising effect on the transformation between postsynaptic current and voltage: the space constant for signal spread in the HC network for the dim-surround condition was roughly twice as large as that for the bright-surround condition. Thus, increasing surround illuminance had analogous effects in the spatial and temporal domains: it restricted the time course and the spatial spread of signal. Both effects were dependent on the contrast between the mean bar illuminance and that of the surround, rather than on overall light level. When the stimulus with the bright surround was dimmed uniformly by a neutral density filter, the space constant did not increase, and response gain at high temporal frequencies did not decrease. Pharmacological experiments performed with dopamine and various agonists and antagonists indicated that, although exogenous dopamine can influence surround enhancement, endogenous dopamine does not play an important role in surround enhancement. We conclude that contrast in background light modulates the spatiotemporal properties of signal processing in the outer retina, and does so by a non-dopaminergic mechanism.
21
Maij, Femke, Alan M. Wing, and W. Pieter Medendorp. "Afferent motor feedback determines the perceived location of tactile stimuli in the external space presented to the moving arm." Journal of Neurophysiology 118, no. 1 (July 1, 2017): 187–93. http://dx.doi.org/10.1152/jn.00286.2016.
Full textAbstract:
People make systematic errors when localizing a brief tactile stimulus in the external space presented on the index finger while moving the arm. Although these errors likely arise in the spatiotemporal integration of the tactile input and information about arm position, the underlying arm position information used in this process is not known. In this study, we tested the contributions of afferent proprioceptive feedback and predictive arm position signals by comparing localization errors during passive vs. active arm movements. In the active trials, participants were instructed to localize a tactile stimulus in the external space that was presented to the index finger near the time of a self-generated arm movement. In the passive trials, each of the active trials was passively replayed in randomized order, using a robotic device. Our results provide evidence that the localization error patterns of the passive trials are similar to the active trials and, moreover, did not lag but rather led the active trials, which suggests that proprioceptive feedback makes an important contribution to tactile localization. To further test which kinematic property of this afferent feedback signal drives the underlying computations, we examined the localization errors with movements that had differently skewed velocity profiles but overall the same displacement. This revealed a difference in the localization patterns, which we explain by a probabilistic model in which temporal uncertainty about the stimulus is converted into a spatial likelihood, depending on the actual velocity of the arm rather than involving an efferent, preprogrammed movement. NEW & NOTEWORTHY We show that proprioceptive feedback of arm motion rather than efferent motor signals contributes to tactile localization during an arm movement. Data further show that localization errors depend on arm velocity, not displacement per se, suggesting that instantaneous velocity feedback plays a role in the underlying computations. Model simulation using Bayesian inference suggests that these errors depend not only on spatial but also on temporal uncertainties of sensory and motor signals.
22
Lewi, Tomer, Nikita A. Butakov, and Jon A. Schuller. "Thermal tuning capabilities of semiconductor metasurface resonators." Nanophotonics 8, no. 2 (November 28, 2018): 331–38. http://dx.doi.org/10.1515/nanoph-2018-0178.
Full textAbstract:
AbstractMetasurfaces exploit optical phase, amplitude, and polarization engineering at subwavelength dimensions to achieve unprecedented control of light. The realization of all dielectric metasurfaces has led to low-loss flat optical elements with functionalities that cannot be achieved with metal elements. However, to reach their ultimate potential, metasurfaces must move beyond static operation and incorporate active tunability and reconfigurable functions. The central challenge is achieving large tunability in subwavelength resonator elements, which requires large optical effects in response to external stimuli. Here we study the thermal tunability of high-index silicon and germanium semiconductor resonators over a large temperature range. We demonstrate thermal tuning of Mie resonances due to the normal positive thermo-optic effect (dn/dT>0) over a wide infrared range. We show that at higher temperatures and longer wavelengths, the sign of the thermo-optic coefficient is reversed, culminating in a negative induced index due to thermal excitation of free carriers. We also demonstrate the tuning of high-order Mie resonances by several linewidths with a temperature swing of ΔT<100 K. Finally, we exploit the large near-infrared thermo-optic coefficient in Si metasurfaces to realize optical switching and tunable metafilters.
23
Tavakol, Ashrafizadeh, Deng, Azarian, Abdoli, Motavaf, Poormoghadam, et al. "Autophagy Modulators: Mechanistic Aspects and Drug Delivery Systems." Biomolecules 9, no. 10 (September 25, 2019): 530. http://dx.doi.org/10.3390/biom9100530.
Full textAbstract:
Autophagy modulation is considered to be a promising programmed cell death mechanism to prevent and cure a great number of disorders and diseases. The crucial step in designing an effective therapeutic approach is to understand the correct and accurate causes of diseases and to understand whether autophagy plays a cytoprotective or cytotoxic/cytostatic role in the progression and prevention of disease. This knowledge will help scientists find approaches to manipulate tumor and pathologic cells in order to enhance cellular sensitivity to therapeutics and treat them. Although some conventional therapeutics suffer from poor solubility, bioavailability and controlled release mechanisms, it appears that novel nanoplatforms overcome these obstacles and have led to the design of a theranostic-controlled drug release system with high solubility and active targeting and stimuli-responsive potentials. In this review, we discuss autophagy modulators-related signaling pathways and some of the drug delivery strategies that have been applied to the field of therapeutic application of autophagy modulators. Moreover, we describe how therapeutics will target various steps of the autophagic machinery. Furthermore, nano drug delivery platforms for autophagy targeting and co-delivery of autophagy modulators with chemotherapeutics/siRNA, are also discussed.
24
Teruel, Miguel A., Elena Navarro, and Pascual González. "Exploiting Awareness for the Development of Collaborative Rehabilitation Systems." Mobile Information Systems 2017 (2017): 1–15. http://dx.doi.org/10.1155/2017/4714328.
Full textAbstract:
Physical and cognitive rehabilitation is usually a challenging activity as people with any kind of deficit have to carry out tasks that are difficult due to their damaged abilities. Moreover, such difficulties become even harder while they have to work at home in an isolated manner. Therefore, the development of collaborative rehabilitation systems emerges as one of the best alternatives to mitigate such isolation and turn a difficult task into a challenging and stimulating one. As any other collaborative system, the need of being aware of other participants (their actions, locations, status, etc.) is paramount to achieve a proper collaborative experience. This awareness should be provided by using those feedback stimuli more appropriately according to the physical and cognitive abilities of the patients. This has led us to define an awareness interpretation for collaborative cognitive and physical systems. This has been defined by extending an existing proposal that has been already applied to the collaborative games field. Furthermore, in order to put this interpretation into practice, a case study based on an association image-writing rehabilitation pattern is presented illustrating how this cognitive rehabilitation task has been extended with collaborative features and enriched with awareness information.
25
de Quadros-Wander, Shikkiah, and Mark Stokes. "The Effect of Mood on Opposite-Sex Judgments of Males' Commitment and Females' Sexual Intent." Evolutionary Psychology 5, no. 3 (July 1, 2007): 147470490700500. http://dx.doi.org/10.1177/147470490700500302.
Full textAbstract:
Gender differences in perceptions of sexual intent and commitment have been the subject of formal and informal inquiry for considerable time. One evolutionary theory, Error Management Theory (EMT), predicts that opposite-sex perceptions of female sexual intent and male commitment intent reflect intrinsic biases that minimize gender-specific evolutionary costs. The results supporting these hypotheses were obtained from subjects regardless of mood. We hypothesized that mood would influence ratings of sexual and commitment intent. Sixty participants (30 males, 30 females) were recruited and exposed to a positive and negative mood condition in counterbalanced groups using video stimuli. Preliminary analyses found an unexpected effect of order of mood induction, necessitating separate analyses of the Positive-Negative (PN) and Negative-Positive (NP) groups. Contrary to the original study, there were no gender effects. Positive moods led to increased ratings of both sexual and commitment intent across genders. Further, negative to positive mood-change was associated with significantly increased ratings. Both males and females attributed significantly higher sexual intent to same-sex rivals than themselves, but only males assessed themselves as having significantly higher commitment intent than same-sex rivals. The EMT model may require adaptation to acknowledge effects of variables such as mood on its predictions of gender-specific biases.
26
Lee, Kang-Woon, Jae-Goo Kim, Karpagam Veerappan, Hoyong Chung, Sathishkumar Natarajan, Ki-Young Kim, and Junhyung Park. "Utilizing Red Spotted Apollo Butterfly Transcriptome to Identify Antimicrobial Peptide Candidates against Porphyromonas gingivalis." Insects 12, no. 5 (May 18, 2021): 466. http://dx.doi.org/10.3390/insects12050466.
Full textAbstract:
Classical antibiotics are the foremost treatment strategy against microbial infections. Overuse of this has led to the evolution of antimicrobial resistance. Antimicrobial peptides (AMPs) are natural defense elements present across many species including humans, insects, bacteria, and plants. Insect AMPs are our area of interest, because of their stronger abilities in host defense. We have deciphered AMPs from an endangered species Parnassius bremeri, commonly known as the red spotted apollo butterfly. It belongs to the second largest insect order Lepidoptera, comprised of butterflies and moths, and lives in the high altitudes of Russia, China, and Korea. We aimed at identifying the AMPs from the larvae stages. The rationale of choosing this stage is that the P. bremeri larvae development occurs at extremely low temperature conditions, which might serve as external stimuli for AMP production. RNA was isolated from larvae (L1 to L5) instar stages and subjected to next generation sequencing. The transcriptomes obtained were curated in in-silico pipelines. The peptides obtained were screened for requisite AMP physicochemical properties and in vitro antimicrobial activity. With the sequential screening and validation, we obtained fifteen candidate AMPs. One peptide TPS–032 showed promising antimicrobial activity against Porphyromonas gingivalis, a primary causative organism of periodontitis.
27
van Hateren, J. H. "Processing of Natural Time Series of Intensities in the Early Visual System of the Blowfly." Perception 26, no. 1_suppl (August 1997): 24. http://dx.doi.org/10.1068/v970023.
Full textAbstract:
The first steps of processing in the visual system of the blowfly are well suited for studying the relationship between the properties of the environment and the function of visual processing (eg Srinivasan et al, 1982 Proceedings of the Royal Society, London B216 427; van Hateren, 1992 Journal of Comparative Physiology A171 157). Although the early visual system appears to be linear to some extent, there are also reports on functionally significant nonlinearities (Laughlin, 1981 Zeitschrift für Naturforschung36c 910). Recent theories using information theory for understanding the early visual system perform reasonably well, but not quite as well as the real visual system when confronted with natural stimuli [eg van Hateren, 1992 Nature (London)360 68]. The main problem seems to be that they lack a component that adapts with the right time course to changes in stimulus statistics (eg the local average light intensity). In order to study this problem of adaptation with a relatively simple, yet realistic, stimulus I recorded time series of natural intensities, and played them back via a high-brightness LED to the visual system of the blowfly ( Calliphora vicina). The power spectra of the intensity measurements and photoreceptor responses behave approximately as 1/ f, with f the temporal frequency, whilst those of second-order neurons (LMCs) are almost flat. The probability distributions of the responses of LMCs are almost gaussian and largely independent of the input contrast, unlike the distributions of photoreceptor responses and intensity measurements. These results suggest that LMCs are in effect executing a form of contrast normalisation in the time domain.
28
Wojtacka, J., J. Szarek, I. Babinska, M. Felsmann, E. Strzyzewska, A. Szarek-Beska, and K. Dublan. "Sodium carbonate intoxication on a chinchilla (Chinchilla lanigera) farm: a case report." Veterinární Medicína 59, No. 2 (March 27, 2014): 112–16. http://dx.doi.org/10.17221/7322-vetmed.
Full textAbstract:
Massive deaths were reported on a chinchilla (Chinchilla lanigera) farm, which over 10 months led to the elimination of the herd. After three months of feeding, longitudinal precipitates inside the pellets were noted. The first symptoms were observed two weeks after the introduction of feed, and included lethargy, decreased mobility, and reduced appetite, as well as increased reactions to external stimuli. Over time, single deaths, hair loss and gnawing, white discolorations on teeth, and polyuria were reported. Haemorrhages of the reproductive tract and mass abortions were observed. Necropsy revealed the presence of transudate with pH = 10, severe hyperaemia of the intestinal mesentery, and extensive regressive lesions in the gastric and intestinal mucosa. Both grossly and microscopically, lesions were noted in the liver, kidneys, adrenal glands, and lungs. The urinary bladder was overfilled. No lesions were observed in the spleen or mesenteric lymph nodes. Histopathology of skin specimens revealed atrophy of the hair follicles. Diagnosis was sodium carbonate intoxication. Owing to the specific features of this species, it was impossible to introduce emetic-based treatment in order to eliminate the toxic agent from the body. No therapeutic measures were undertaken because of the late diagnosis of the toxic agent and late removal of feed, as well as extensive lesions on the gastrointestinal mucosa.
29
TSUKADA, KIMIKO. "Cross-language perception of word-final stops in Thai and English." Bilingualism: Language and Cognition 9, no. 3 (October 20, 2006): 309–18. http://dx.doi.org/10.1017/s1366728906002653.
Full textAbstract:
This study examined Australian English (AE) and Thai–English bilingual (TE) speakers' ability to perceive word-final stops in their native and non-native languages. In the perception experiment, the TE listeners were able to discriminate stop contrasts differing only in place of articulation (/p/–/t/, /p/–/k/, /t/–/k/) in both English and Thai accurately, but the AE listeners' discrimination was accurate only for English. The listeners' discrimination accuracy was differentially influenced by the type of stop contrast they heard. The Thai /p/–/t/ contrast was most discriminable for both groups of listeners, in particular, the AE listeners. Acoustic analyses of the Thai stimuli presented in the perception experiment were conducted in order to search for cues that led to different response patterns for the AE and TE listeners. There was a clear effect of the final stop on the formant trajectories of /a/ and /u/, suggesting that these acoustic differences may be audible to the listeners. The results provide further evidence that first language (L1) transfer alone is insufficient to account for listeners' response patterns in cross-language speech perception and that it is necessary to take into account phonetic realization of sounds and/or the amount of acoustic information contained in the speech signal to predict accuracy with which sound contrasts are discriminated.
30
Nanjundaswamy, Manohar, Prashanth Prabhu, Revathi Rajanna, Raghavendra Ningegowda, and Madhuri Sharma. "Computer-Based Auditory Training Programs for Children with Hearing Impairment – A Scoping Review." International Archives of Otorhinolaryngology 22, no. 01 (April 28, 2017): 088–93. http://dx.doi.org/10.1055/s-0037-1602797.
Full textAbstract:
Introduction Communication breakdown, a consequence of hearing impairment (HI), is being fought by fitting amplification devices and providing auditory training since the inception of audiology. The advances in both audiology and rehabilitation programs have led to the advent of computer-based auditory training programs (CBATPs). Objective To review the existing literature documenting the evidence-based CBATPs for children with HIs. Since there was only one such article, we also chose to review the commercially available CBATPs for children with HI. The strengths and weaknesses of the existing literature were reviewed in order to improve further researches. Data Synthesis Google Scholar and PubMed databases were searched using various combinations of keywords. The participant, intervention, control, outcome and study design (PICOS) criteria were used for the inclusion of articles. Out of 124 article abstracts reviewed, 5 studies were shortlisted for detailed reading. One among them satisfied all the criteria, and was taken for review. The commercially available programs were chosen based on an extensive search in Google. The reviewed article was well-structured, with appropriate outcomes. The commercially available programs cover many aspects of the auditory training through a wide range of stimuli and activities. Conclusions There is a dire need for extensive research to be performed in the field of CBATPs to establish their efficacy, also to establish them as evidence-based practices.
31
Lyons, Paul, and Randall Bandura. "Employee turnover: features and perspectives." Development and Learning in Organizations: An International Journal 34, no. 1 (September 11, 2019): 1–4. http://dx.doi.org/10.1108/dlo-02-2019-0048.
Full textAbstract:
Purpose This viewpoint provides the individual manager or supervisor with foundational information in order to better grasp the critical aspects of employee interest in leaving or staying on the job, and some suggestions for influencing talented employees to stay with the organization. Design/methodology/approach Design involves two distinct features. First, a comprehensive review of empirical research on the topics of turnover and turnover intention helps to identify and then summarize the most agreed-upon characteristics that define employee turnover. Second, relying upon published reports and empirical research the intention is to identify those interventions a manager or supervisor may undertake to counter turnover among valued employees. Findings The reviews undertaken led to several motivators or stimuli that encouraged an employee to leave or stay with an organization. It was discovered that turnover is much more complex than matters relating to job satisfaction, compensation, or an undesirable boss. The various motivators for leaving or staying present several opportunities for managerial intervention aimed at retaining talented employees. Originality/value The value of this viewpoint is the concise presentation of the critical aspects of a work environment that influence an employee to stay or leave an organization. These aspects are expressed such that a manager or supervisor is guided about actions to take to enhance the retention of desirable employees.
32
Wright, W. N., B. L. Bardakjian, T. A. Valiante, J. L. Perez-Velazquez, and P. L. Carlen. "White noise approach for estimating the passive electrical properties of neurons." Journal of Neurophysiology 76, no. 5 (November 1, 1996): 3442–50. http://dx.doi.org/10.1152/jn.1996.76.5.3442.
Full textAbstract:
1. The passive electrical properties of whole cell patched dentate granule cells were studied with the use of zero-mean Gaussian white noise current stimuli. Transmembrane voltage responses were used to compute the first-order Wiener kernels describing the current-voltage relationship at the soma for six cells. Frequency domain optimization techniques using a gradient method for function minimization were then employed to identify the optimal electrical parameter values. Low-power white noise stimuli are presented as a favorable alternative to the use of short-pulse current inputs for investigating neuronal passive electrical properties. 2. The optimization results demonstrated that the lumped resistive and capacitive properties of the recording electrode must be included in the analytic input impedance expression to optimally fit the measured cellular responses. The addition of the electrode resistance (Re) and capacitance (Ce) to the original parameters (somatic conductance, somatic capacitance, axial resistance, dendritic conductance, and dendritic capacitance) results in a seven-parameter model. The mean Ce value from the six cells was 5.4 +/- 0.3 (SE) pF, whereas Re following formation of the patch was found to be 20 +/- 2 M omega. 3. The six dentate granule cells were found to have an input resistance of 600 +/- 20 M omega and a dendritic to somatic conductance ratio of 6.3 +/- 1.1. The electronic length of the equivalent dendritic cylinder was found to be 0.42 +/- 0.03. The membrane time constant in the soma was found to be 13 +/- 3 ms, whereas the membrane time constant of the dendrites was 58 +/- 5 ms. Incorporation of morphological estimations led to the following distributed electrical parameters: somatic membrane resistance = 25 +/- 4 k omega cm2, somatic membrane capacitance = 0.48 +/- 0.05 microF/cm2, Ri (input resistance) = 72 +/- 5 omega cm, dendritic membrane resistance = 59 +/- 4 k omega cm2, and dendritic membrane capacitance = 0.97 +/- 0.06 microF/cm2. On the basis of capacitive measurements, the ratio of dendritic surface area to somatic surface area was found to be 34 +/- 2. 4. For comparative purposes, hyperpolarizing short pulses were also injected into each cell. The short-pulse input impedance measurements were found to underestimate the input resistance of the cell and to overestimate both the somatic conductance and the membrane time constants relative to the white noise input impedance measurements.
33
Lickiewicz, Jakub, Katarzyna Piotrowicz, Patricia Paulsen Hughes, and Marta Makara-Studzińska. "Weather and Aggressive Behavior among Patients in Psychiatric Hospitals—An Exploratory Study." International Journal of Environmental Research and Public Health 17, no. 23 (December 7, 2020): 9121. http://dx.doi.org/10.3390/ijerph17239121.
Full textAbstract:
Background: The number of meteoropaths, or people negatively affected by weather conditions, is rising dramatically. Meteoropathy is developing rapidly due to ever poorer adaptations of people to changes in weather conditions. Strong weather stimuli may not only exacerbate symptoms in people with diseases of the cardiovascular and respiratory systems but may also induce aggressive behavior. Researchers have shown that patients suffering from mental illnesses are most vulnerable to changes in the weather and postulate a connection between the seasons and aggressive behavior. Methods: The goal of the study was to analyze the relationship between coercive measures and weather factors. The researchers identified what meteorological conditions prevailed on days with an increased number of incidents of aggressive behavior leading to the use of physical coercion towards patients in a psychiatric hospital in Poland. In order to determine the impact of weather conditions on the frequency at which physical coercion measures were used, the hospital’s “coercion sheets” from 1 January 2015 to 31 March 2017 were analyzed. The data were correlated with meteorological data. In order to determine the relationship between the occurrence of specific weather conditions and the number of coercive interventions (N), researchers utilized Spearman’s rank correlation analysis together with two-dimensional scatter diagrams (dependency models), multiple regression, stepwise regression, frequencies, and conditional probability (%). Results: Lower barometric pressure and foehn wind increased aggressive behavior in patients that led to coercive measures. For temperature (positive correlation) and humidity (negative correlation), there was a poor but statistically significant correlation. Conclusions: Monitoring weather conditions might be useful in predicting and preventing aggression by patients who are susceptible to weather changes
34
Coffey, Vernon G., Henriette Pilegaard, Andrew P. Garnham, Brendan J. O'Brien, and John A. Hawley. "Consecutive bouts of diverse contractile activity alter acute responses in human skeletal muscle." Journal of Applied Physiology 106, no. 4 (April 2009): 1187–97. http://dx.doi.org/10.1152/japplphysiol.91221.2008.
Full textAbstract:
We examined acute molecular responses in skeletal muscle to divergent exercise stimuli by combining consecutive bouts of resistance and endurance exercise. Eight men [22.9 ± 6.3 yr, body mass of 73.2 ± 4.5 kg, peak O2 uptake (V̇o2peak) of 54.0 ± 5.7 ml·kg−1·min−1] were randomly assigned to complete trials consisting of either resistance exercise (8 × 5 leg extension, 80% 1 repetition maximum) followed by a bout of endurance exercise (30 min cycling, 70% V̇o2peak) or vice versa. Muscle biopsies were obtained from the vastus lateralis at rest, 15 min after each exercise bout, and after 3 h of passive recovery to determine early signaling and mRNA responses. Phosphorylation of Akt and Akt1Ser473 were elevated 15 min after resistance exercise compared with cycling, with the greatest increase observed when resistance exercise followed cycling (∼55%; P < 0.01). TSC2-mTOR-S6 kinase phosphorylation 15 min after each bout of exercise was similar regardless of the exercise mode. The cumulative effect of combined exercise resulted in disparate mRNA responses. IGF-I mRNA content was reduced when cycling preceded resistance exercise (−42%), whereas muscle ring finger mRNA was elevated when cycling was undertaken after resistance exercise (∼52%; P < 0.05). The hexokinase II mRNA level was higher after resistance cycling (∼45%; P < 0.05) than after cycling-resistance exercise, whereas modest increases in peroxisome proliferator-activated receptor gamma coactivator-1α mRNA did not reveal an order effect. We conclude that acute responses to diverse bouts of contractile activity are modified by the exercise order. Moreover, undertaking divergent exercise in close proximity influences the acute molecular profile and likely exacerbates acute “interference.”
35
Nashner, L. M., and H. Forssberg. "Phase-dependent organization of postural adjustments associated with arm movements while walking." Journal of Neurophysiology 55, no. 6 (June 1, 1986): 1382–94. http://dx.doi.org/10.1152/jn.1986.55.6.1382.
Full textAbstract:
This study examines the interactions between anteroposterior postural responses and the control of walking in human subjects. In the experimental paradigm, subjects walked upon a treadmill, gripping a rigid handle with one hand. Postural responses at different phases of stepping were elicited by rapid arm pulls or pushes against the handle. During arm movements, EMG's recorded the activity of representative arm, ankle, and thigh segment muscles. Strain gauges in the handle measured the force of the arm movement. A Selspot II system measured kinematics of the stepping movements. The duration of support and swing phases were marked by heel and toe switches in the soles of the subjects' shoes. In the first experiment, subjects were instructed to pull on the handle at their own pace. In these trials all subjects preferred to initiate pulls near heel strikes. Next, when instructed to pull as rapidly as possible in response to tone stimuli, reaction times were similar for all phases of the step cycle. Leg muscle responses associated with arm pulls and pushes, referred to as “postural activations,” were directionally specific and preceded arm muscle activity. The temporal order and spatial distribution of postural activations in the muscles of the support leg were similar when arm pull movements occurred while the subject was standing in place and after heel strike while walking. Activations began in the ankle and radiated proximally to the thigh and then the arm. Activations of swing leg muscles were also directionally specific and involved flexion and forward or backward thrust of the limb. When arm movements were initiated during transitions from support by one leg to the other, patterns of postural activations were altered. Alterations usually occurred 10-20 ms before hell strikes and involved changes in the timing and sometimes the spatial structure of postural activations. Postural activation patterns are similar during in-place standing and during the support phase of locomotion. Walking and posture control appear to be separately organized but interrelated activities. Our results also suggest that the stepping generators, not peripheral feedback time locked to heel strikes, modulate postural activation patterns.
36
Fiorineschi, Lorenzo, Francesco Saverio Frillici, and Federico Rotini. "Challenging COVID-19 with Creativity: Supporting Design Space Exploration for Emergency Ventilators." Applied Sciences 10, no. 14 (July 18, 2020): 4955. http://dx.doi.org/10.3390/app10144955.
Full textAbstract:
The high concentration and rapid increase in lung diseases caused by COVID-19 has suddenly led medical staff to face a lack of ventilators in emergency situations. In this context, many enthusiasts and/or designers all over the world have started to think about low cost and open-source solutions for emergency ventilators, with the aim of providing concrete aid. In a small amount of time, many different solutions have been proposed, most of which are based on the automatic compression of the auxiliary manual breathing unit (AMBU) bag. In particular, many different designs have been conceived for the AMBU compression mechanism, which contains the most critical parts to be designed. Here arises the aim of this work, i.e., to propose a methodological approach to support the creativity of designers involved in inventing increasingly sustainable and reliable low-cost compression mechanisms for AMBU-based ventilators. Accordingly, a conceptual framework is proposed, capable of collecting existing ideas and organizing the underpinning concepts, to provide stimuli for new idea generation and to keep track of (and possibly to share) the explored design space. Illustrative examples are provided in order to show how the proposal can be used in practice. In particular, a set of currently available solutions is schematically shown through the proposed graphical tools, and the generation of new illustrative solutions is presented. Additionally, it is shown how to represent further ideas (e.g., those coming from other teams) in the framework.
37
Rowell, L. B., D. G. Johnson, P. B. Chase, K. A. Comess, and D. R. Seals. "Hypoxemia raises muscle sympathetic activity but not norepinephrine in resting humans." Journal of Applied Physiology 66, no. 4 (April 1, 1989): 1736–43. http://dx.doi.org/10.1152/jappl.1989.66.4.1736.
Full textAbstract:
The experimental objective was to determine whether moderate to severe hypoxemia increases skeletal muscle sympathetic nervous activity (MSNA) in resting humans without increasing venous plasma concentrations of norepinephrine (NE) and epinephrine (E). In nine healthy subjects (20–34 yr), we measured MSNA (peroneal nerve), venous plasma levels of NE and E, arterial blood pressure, heart rate, and end-tidal O2 and CO2 before (control) and during breathing of 1) 12% O2 for 20 min, 2) 10% O2 for 20 min, and 3) 8% O2 for 10 min--in random order. MSNA increased above control in five, six, and all nine subjects during 12, 10, and 8% O2, respectively (P less than 0.01), but only after delays of 12 (12% O2) and 4 min (8 and 10% O2). MSNA (total activity) rose 83 +/- 20, 260 +/- 146, and 298 +/- 109% (SE) above control by the final minute of breathing 12, 10, and 8% O2, respectively. NE did not rise above control at any level of hypoxemia; E rose slightly (P less than 0.05) at one time only with both 10 and 8% O2. Individual changes in MSNA during hypoxemia were unrelated to elevations in heart rate or decrements in blood pressure and end-tidal CO2--neither of which always fell. We conclude that in contrast to some other sympathoexcitatory stimuli such as exercise or cold stress, moderate to severe hypoxemia increases leg MSNA without raising plasma NE in resting humans.
38
Lempke, Landon B., Jeonghoon Oh, Rachel S. Johnson, Julianne D. Schmidt, and Robert C. Lynall. "Single- Versus Dual-Task Functional Movement Paradigms: A Biomechanical Analysis." Journal of Sport Rehabilitation 30, no. 5 (July 1, 2021): 774–85. http://dx.doi.org/10.1123/jsr.2020-0310.
Full textAbstract:
Context: Laboratory-based movement assessments are commonly performed without cognitive stimuli (ie, single-task) despite the simultaneous cognitive processing and movement (ie, dual task) demands required during sport. Cognitive loading may critically alter human movement and be an important consideration for truly assessing functional movement and understanding injury risk in the laboratory, but limited investigations exist. Objective: To comprehensively examine and compare kinematics and kinetics between single- and dual-task functional movement among healthy participants while controlling for sex. Design: Cross-sectional study. Setting: Laboratory. Patients (or Other Participants): Forty-one healthy, physically active participants (49% female; 22.5 ± 2.1 y; 172.5 ± 11.9 cm; 71.0 ± 13.7 kg) enrolled in and completed the study. Intervention(s): All participants completed the functional movement protocol under single- and dual-task (subtracting by 6s or 7s) conditions in a randomized order. Participants jumped forward from a 30-cm tall box and performed (1) maximum vertical jump landings and (2) dominant and (3) nondominant leg, single-leg 45° cuts after landing. Main Outcome Measures: The authors used mixed-model analysis of variances (α = .05) to compare peak hip, knee, and ankle joint angles (degrees) and moments (N·m/BW) in the sagittal and frontal planes, and peak vertical ground reaction force (N/BW) and vertical impulse (Ns/BW) between cognitive conditions and sex. Results: Dual-task resulted in greater peak vertical ground reaction force compared with single-task during jump landing (mean difference = 0.06 N/BW; 95% confidence interval [CI], 0.01 to 0.12; P = .025) but less force during dominant leg cutting (mean difference = −0.08 N/BW; 95% CI, −0.14 to −0.02; P = .015). Less hip-flexion torque occurred during dual task than single task (mean difference = −0.09 N/BW; 95% CI, −0.17 to −0.02). No other outcomes were different between single and dual task (P ≥ .053). Conclusions: Slight, but potentially important, kinematic and kinetic differences were observed between single- and dual-task that may have implications for functional movement assessments and injury risk research. More research examining how various cognitive and movement tasks interact to alter functional movement among pathological populations is warranted before clinical implementation.
39
Rokem, Ariel, Sebastian Watzl, Tim Gollisch, Martin Stemmler, Andreas V. M. Herz, and Inés Samengo. "Spike-Timing Precision Underlies the Coding Efficiency of Auditory Receptor Neurons." Journal of Neurophysiology 95, no. 4 (April 2006): 2541–52. http://dx.doi.org/10.1152/jn.00891.2005.
Full textAbstract:
Sensory systems must translate incoming signals quickly and reliably so that an animal can act successfully in its environment. Even at the level of receptor neurons, however, functional aspects of the sensory encoding process are not yet fully understood. Specifically, this concerns the question how stimulus features and neural response characteristics lead to an efficient transmission of sensory information. To address this issue, we have recorded and analyzed spike trains from grasshopper auditory receptors, while systematically varying the stimulus statistics. The stimulus variations profoundly influenced the efficiency of neural encoding. This influence was largely attributable to the presence of specific stimulus features that triggered remarkably precise spikes whose trial-to-trial timing variability was as low as 0.15 ms—one order of magnitude shorter than typical stimulus time scales. Precise spikes decreased the noise entropy of the spike trains, thereby increasing the rate of information transmission. In contrast, the total spike train entropy, which quantifies the variety of different spike train patterns, hardly changed when stimulus conditions were altered, as long as the neural firing rate remained the same. This finding shows that stimulus distributions that were transmitted with high information rates did not invoke additional response patterns, but instead displayed exceptional temporal precision in their neural representation. The acoustic stimuli that led to the highest information rates and smallest spike-time jitter feature pronounced sound-pressure deflections lasting for 2–3 ms. These upstrokes are reminiscent of salient structures found in natural grasshopper communication signals, suggesting that precise spikes selectively encode particularly important aspects of the natural stimulus environment.
40
Weksberg, David C., Carl G. Feng, Alan Sher, and Margaret A. Goodell. "The P47 GTPase Lrg-47 Links Host Defense and HSC Proliferation." Blood 110, no. 11 (November 16, 2007): 640. http://dx.doi.org/10.1182/blood.v110.11.640.640.
Full textAbstract:
Abstract Hematopoietic stem cells (HSCs) are largely quiescent, self-renewing cells that give rise to all adult blood lineages. They have a remarkable capacity to respond to proliferative stimuli from a variety of insults, exiting their quiescent phase and undergoing a period of self-renewal and differentiation in order to restore hematopoietic homeostasis. Yet, while some molecular controls on the cycle of HSC activation and quiescence have been elucidated, little is known about the mechanisms linking this process to natural signals, such as the stress of an immune response to chronic infection. Previous work in our laboratory examined gene expression changes in a cycle of activation, expansion, and return to quiescence in HSCs stimulated by the chemotherapeutic agent 5-fluorouracil (5FU). One family of genes identified by this approach encodes the interferon-inducible p47 GTPases, which has been previously characterized solely in the context of the immune response to intracellular infections. Interestingly, mice deficient for one member of this family, Lrg-47, had been observed to develop a major hematopoietic defect in the face of infectious challenge. This combination of findings led us to test the novel hypothesis that Lrg-47 might regulate HSC function in the face of either chemical or pathogenic stress. We found that, while Lrg-47 −/ − mice have largely normal blood counts under homeostasis, these animals exhibited impaired hematopoietic recovery from stress in the form of sublethal irradiation or 5FU treatment. Furthermore, we show that HSCs deficient in Lrg-47 are profoundly compromised in functional repopulation assays, even when given extreme advantages over competitor marrow. We also observed, in BrdU labeling studies, that Lrg-47 −/ − HSCs display dysregulated HSC proliferation, with substantially increased turnover at baseline. We found that this inappropriate proliferation has a functional consequence, as Lrg-47 −/ − mice have a delayed expansion of the HSC compartment following 5FU treatment. Finally, in order to investigate the response of stem and progenitor populations to infectious stimuli, we challenged mice by infection with Mycobacterium avium. Phenotypic and functional assays demonstrated that, while wild-type progenitors expand dramatically in response to infection, Lrg-47 −/ − mice show a stark defect. Our findings thus point to a dual role for Lrg-47 - first as an inhibitor of HSC proliferation in the steady state, and second as a key regulator of HSCs in the response to injury. Overall, our results establish a link between the response to infection and HSC activation, and demonstrate a novel function for a member of the p47GTPase family. Additionally, as Lrg-47 has been chiefly known as an effector of IFNgamma signalling, our results suggest a possible mechanism for the inhibitory effects of this cytokine on hematopoiesis, with implications for human diseases with interferon-related pathogenesis. Most generally, our findings reveal an unexpected intersection point between the fields of stem cell biology and the immune response to pathogens, and suggest that defects in HSC function should be considered as possible determinants of host susceptibility to infection.
41
Reinaldo, Rafael, Ulysses Albuquerque, and Patrícia Medeiros. "Taxonomic affiliation influences the selection of medicinal plants among people from semi-arid and humid regions—a proposition for the evaluation of utilitarian equivalence in Northeast Brazil." PeerJ 8 (August 4, 2020): e9664. http://dx.doi.org/10.7717/peerj.9664.
Full textAbstract:
Background This study sought to investigate the occurrence of taxonomic patterns between semi-arid and humid regions, verifying how the taxonomic affiliation can influence the selection of plants for medicinal purposes and act as a selection criterion. Methods The relationship between the taxonomic affiliation and the selection of medicinal plants with four different communities was analyzed; two of them associated with a seasonally dry tropical forest and the other two associated with a tropical rain forest. We used the Utilitarian Equivalence Model (transposing the concept of ecological equivalence, proposed by Odum, for ethnobotany) to test the hypothesis that species that have the same taxonomic affiliation tend to have the same therapeutic applications in different environments (utilitarian equivalence). In addition, we used the Utilitarian Redundancy Model to verify whether, within the same medical system, plants of the same taxonomic affiliation tend to be redundant (treating the same diseases). Results We found that a pair of plants of the same genus were 9.25 times more likely to be equivalent than a different genus pair (OR = 9.25, CI [1.68–51.02], p < 0.05). When we analyzed the species used by the same population, the chances of a pair having similar therapeutic uses (utilitarian redundancy) increased when they were species of the same family (OR = 1.94, CI [1.06−3.53]; p < 0.05). Conclusions These findings confirm the hypothesis that there is an influence of taxonomic affiliation, in terms of genera and family, on the selection of medicinal plants in semi-arid and humid areas in Northeast Brazil. In addition, our Utilitarian Equivalence Model can be an important tool in the search for more common selection criteria, in order to identify the shared characteristics among the equivalent pairs and consequently the main types of perceptions or stimuli that led to the inclusion of such species in local pharmacopoeias.
42
McLean, J., S. Raab, and L. A. Palmer. "Contribution of linear mechanisms to the specification of local motion by simple cells in areas 17 and 18 of the cat." Visual Neuroscience 11, no. 2 (March 1994): 271–94. http://dx.doi.org/10.1017/s0952523800001632.
Full textAbstract:
AbstractA reverse correlation technique, which permits estimation of three-dimensional first-order properties of receptive fields (RFs), was applied to simple cells in areas 17 and 18 of cat. Two classes of simple cells were found. For one class, the spatial and temporal RF characteristics were Separable, i.e. they could be synthesized as the product of spatial and temporal weighting functions. RFs in the other class were Inseparable, i.e. bright and dark subregions comprising each field were obliquely oriented in space-time. Based on a linear superposition model, these observations led to testable hypotheses: (1) simple cells with separable space-time characteristics should be speed but not direction selective and (2) simple cells with inseparable space-time characteristics should be direction selective and the optimal velocity of moving stimuli should be predictable from the slope of the oriented subregions. These hypotheses were tested by comparing responses to moving bars with those predicted by application of the convolution integral. Linear predictions accounted for waveforms of responses to moving bars in detail. For cells with oriented space-time characteristics, the preferred direction was always predicted correctly and the optimal speed was predicted quite well. Most cells with separable space-time characteristics were not direction selective as predicted. The major discrepancies between measured and predicted behavior were twofold. First, 8/32 cells with separable space-time RFs were direction selective. Second, predicted directional indices were weakly correlated with actual measurements. These conclusions hold for simple cells in both areas 17 and 18. The major difference between simple RFs in these areas is the coarser spatial scale seen in area 18. These results demonstrate a significant linear contribution to the speed and direction selectivity of simple cells in areas 17 and 18. Where additional, nonlinear mechanisms are inferred, they appear to act synergistically with the linear mechanism.
43
Uhl, Franziska Maria, Sophia Chen, David O'Sullivan, Michael Buck, Jörg Büscher, Dietmar Pfeifer, Jürgen Finke, et al. "Metabolic Reprogramming Overcomes T Cell Inhibition By AML Cells." Blood 132, Supplement 1 (November 29, 2018): 3328. http://dx.doi.org/10.1182/blood-2018-99-112897.
Full textAbstract:
Abstract Allogeneic hematopoietic cell transplantation (allo-HCT) is the treatment strategy of choice for the majority of patients with acute myeloid leukemia (AML). However, about 40% of patients relapse, which is associated with a poor prognosis. Donor lymphocyte infusions (DLIs) induce remission only in a minority of relapsed AML patients. In order to understand the impact of AML cells on T cell bioenergetics, we investigated the metabolic phenotype and immunological profile of CD8+ T cells isolated from AML patients at primary diagnosis, during remission and relapse after allo-HCT. At diagnosis, T cells exhibited robust metabolic activity and strong immune activation. In contrast, during relapse, T cells demonstrated reduced glycolytic and respiratory activity compared to their status at remission. The metabolic phenotype was accompanied by reduced cytotoxic ability. Metabolomics revealed lactate accumulation and substantial arginine depletion in the serum of these patients. The results observed in the human setting could be reproduced in a murine graft versus leukemia (GVL) model where T cells isolated from AML bearing mice exhibited lower metabolic activity compared to control animals. In vitro co-culture experiments enabled tightly controlled conditions for mechanistic studies. The metabolic impairment induced by AML cells was mediated by soluble factors, mirroring the major changes in serum metabolites of patients, and interfered with the crucial metabolic reprogramming in the priming phase of T cells. Well-known mechanisms such as nutrient deprivation could be excluded. Extensive transcriptomic and metabolomic analyses have been undertaken in order to identify the molecules responsible for the diminished metabolic activation. Influencing mitochondrial architecture thereby boosting respiratory activity prior to infusion led to enhanced anti-leukemic activity of T cells in vivo. The pre-treatment favored an immunological memory phenotype essential for a potent GVL effect. Using metabolic stimuli as pre-treatment of DLIs could promote T cell resistance against tumor evasion and increase anti-tumor immunity. This could greatly improve the success of DLIs and other adoptive T cell transfer strategies in the treatment of AML relapse. Disclosures Finke: Neovii: Consultancy, Honoraria, Other: travel grants, Research Funding; Medac: Consultancy, Honoraria, Other: travel grants, Research Funding; Novartis: Consultancy, Honoraria, Other: travel grants, Research Funding; Riemser: Consultancy, Honoraria, Research Funding.
44
Koerber, H. R., G. Hobbs, and P. B. Brown. "Precision and variability of hindlimb representation in cat dorsal horn and implications for tactile localization." Journal of Neurophysiology 70, no. 6 (December 1, 1993): 2489–501. http://dx.doi.org/10.1152/jn.1993.70.6.2489.
Full textAbstract:
1. One hundred fifty-eight cells were recorded extracellularly in rows of tracks spanning both left and right dorsal horns, at segmental boundaries and midsegment in segments L5-S1, in six anesthetized cats. For each cell the low-threshold cutaneous mechano-receptive field was determined with the use of hand-held probes, and the recording site was marked with a microlesion. Recording sites were reconstructed, and the mediolateral (ML) and rostrocaudal (RC) locations of each cell were recorded along with the location of the cell's receptive field, expressed as distance from tips of toes (D). 2. Ninety-five percent of pairs of cells recorded from bilaterally symmetric locations (+/- 10%) in the same animal had receptive fields on opposite legs that had components that were mirror symmetric. Only 42% of cell pairs deviating from bilateral symmetry by approximately +/- 240 microns had receptive fields with overlapping components. This indicated that there was a substantial bilateral symmetry that was not simply due to large receptive fields. 3. The trajectories of receptive fields of cells in a single row of tracks were plotted in order of mediolateral recording site, going from medial to lateral, combining both sides. These trajectories followed a distoproximal course on the leg. Of 144 adjacent cells used to plot these trajectories, with an average spacing of approximately 120 microns, only 6 reversals of the distoproximal gradient polarity were observed within animals. 4. Data from individual animals were shifted rostrally and caudally, to obtain best agreement of mediolateral somatotopic gradients with the combined data from the other animals in the sample. Best agreement was obtained with shifts ranging from 0.3 segment rostral to 0.4 segment caudal, with an average absolute value shift of 0.22 segment. 5. By comparing cell pairs within the same dorsal horn, on opposite sides of the same animal, and across animals, variability in cell placement given the average map and the receptive field could be calculated. Interanimal variability and bilateral asymmetry were approximately +/- 60 microns, and within-dorsal horn variability was approximately +/- 35 microns. The interanimal variability is equivalent to a variability of distoproximal receptive-field location on the leg of +/- 13 mm, with a smaller variability in areas of high magnification (e.g., the toes), and a larger variability in areas with small magnification (e.g., the thigh). This degree of variability is consistent with the ability of animals with transected dorsal columns to localize tactile stimuli with a normal degree of precision.
45
Alamome, Isabelle, Jean Feuillard, and Nathalie Faumont. "NF-κB Independent Protection Against Apoptosis by Overexpression of A20 in B-Cells." Blood 118, no. 21 (November 18, 2011): 5233. http://dx.doi.org/10.1182/blood.v118.21.5233.5233.
Full textAbstract:
Abstract Abstract 5233 Introduction In Activated B-Cell like Diffuse Large B-Cell Lymphomas (ABC DLBCLs) the most commonly affected gene is TNFAIP3, which encodes A20, an ubiquitin modifying enzyme involved in the negative regulation of NF-κB signaling. A20 is itself a target gene of NF-κB and needs to be induced in order to exert its negative feedback effect on NF-κB. Mutations resulting in the inactivation of A20 have been found in a significant proportion of ABC DLBCL cases (Compagno M et al, Nature 2009). The tumor suppressor role of A20 was established by the reintroduction of wild-type A20 in some mutant A20 lymphoma B-cell lines promoting apoptosis, supposedly due to the loss of the ability to inactivate NF-κB. However, a protective effect of A20 against apoptotic stimuli was demonstrated in some cell types. In endothelial cells, A20 protects from TNF- and Fas-mediated apoptosis by inhibiting caspase-8 activation (Daniel S et al, Blood 2004). We thus wanted to understand the relationship between A20 expression, NF-κB activation and protection against apoptosis in B-cells. Methods We have cloned cDNAs coding for wild-type A20 (A20wt), for IκBαS32,36A (constitutively active form of IκBα), and for luciferase (as a control) into a doxycycline double-inducible episomal vector pRT-1, and stably transfected these vectors into an EBV positive lymphoblastoid B-cells line. Induction of p53 mediated apoptosis was performed by treatment of cells with Fludarabine*, whereas induction of caspase-8 dependant was performed with agonist antibodies against Fas (CD95). Results Both A20 and IκBαS32,36A overexpression suppressed NF-κB activity with downregulation of NF-κB target genes. Loss of NF-κB activation by induction of IκBαS32,36A led to increase of spontaneous apoptosis. Oppositely, loss of NF-κB activation by induction of A20 led to decrease of spontaneous apoptosis. Compared with luciferase transfected cells, no effect of A20 overexpression was seen after treatment of cells with anti-CD95 antibodies. Caspase-9 cleavage was significantly decreased and increase of TP53 protein levels was lower in A20 overexpressing cells after Fludarabine* treatment. By contrast, Fludarabine* treatment of IκBαS32,36A expressing cells led to an increase of both TP53 protein levels and caspase-9 cleavage. Therefore, A20 negatively modulated mitochondrial apoptosis pathway despite NF-κB downregulation. Conclusions These results suggest that A20 may exert an anti-apoptotic effect on its own independently of NF-κB activation. We are now looking after the functional properties of A20 natural mutants. Indeed, we can hypothesize that A20 mutants described in ABC DLBCLs have lost their negative feedback effect on NF-κB, but not their protective effect against apoptosis. So, A20 mutants may actively contribute to oncogenesis through their own protective effect on tumor cells. Disclosures: No relevant conflicts of interest to declare.
46
Nicolas, Samer, Sandra Abdellatef, Maria Al Haddad, Isabelle Fakhoury, and Mirvat El-Sibai. "Hypoxia and EGF Stimulation Regulate VEGF Expression in Human Glioblastoma Multiforme (GBM) Cells by Differential Regulation of the PI3K/Rho-GTPase and MAPK Pathways." Cells 8, no. 11 (November 6, 2019): 1397. http://dx.doi.org/10.3390/cells8111397.
Full textAbstract:
Glioblastoma multiforme (GBM) is one of the most common and deadly cancers of the central nervous system (CNS). It is characterized by the presence of hypoxic regions, especially in the core, leading to an increase in vascularity. This increased vascularization is driven by the expression of the major angiogenic inducer VEGF and the indirect angiogenic inducer Epidermal growth factor (EGF), which stimulates VEGF expression. In this study, we examine the regulation of VEGF by both hypoxia and the EGF signaling pathway. We also examine the involvement of pathways downstream from EGF signaling, including the mitogen-activated protein kinase/extracellular regulated kinase (MAPK/ERK) pathway and the Phosphatidylinositol-3-kinase/RhoA/C (PI3K/RhoA/C) pathway in this regulation. Our results show that VEGF expression and secretion levels increase following either hypoxia or EGF stimulation, with the two stimuli signaling in parallel. We also observed an increase in ERK and protein kinase B (Akt) phosphorylation, in response to EGF stimulation, with kinetics that correlated with the kinetics of the effect on VEGF. Using pharmacological inhibitors against ERK and PI3K and small interfering RNAs (siRNAs) against RhoA and RhoC, we found that both the ERK and the PI3K/RhoA/C pathways have to cooperate in order to lead to an increase in VEGF expression, downstream from EGF. In response to hypoxia, however, only ERK was involved in the regulation of VEGF. Hypoxia also led to a surprising decrease in the activation of PI3K and RhoA/C. Finally, the decrease in the activation of these Rho-GTPases was found to be mediated through a hypoxia-driven overexpression of the Rho-GTPase GTPase activating protein (GAP), StarD13. Therefore, while under normoxic conditions, EGF stimulates the activation of both the PI3K and the MAPK pathways and the induction of VEGF, in glioblastoma cells, hypoxic conditions lead to the suppression of the PI3K/RhoA/C pathway and an exclusive switch to the MAPK pathway.
47
Grieco, Alba, and Sergio Roncato. "Lines That Induce Phenomenal Transparency." Perception 34, no. 4 (April 2005): 391–407. http://dx.doi.org/10.1068/p5142.
Full textAbstract:
Three neighbouring opaque surfaces may appear split into two layers, one transparent and one opaque beneath, if an outline contour is drawn that encompasses two of them. The phenomenon was originally observed by Kanizsa [1955 Rivista di Psicologia69 3–19; 1979 Organization in Vision: Essays on Gestalt Psychology (New York: Praeger)], for the case where an outline contour is drawn to encompass one of the two parts of a bicoloured figure and a portion of a background of lightest (or darkest) luminance. Preliminary observations revealed that the outline contour yields different effects: in addition to the stratification into layers described by Kanizsa, a second split, opposite in depth order, may occur when the outline contour is close in luminance to one of the three surfaces. An initial experiment was designed to investigate what conditions give rise to the two phenomenal transparencies: this led to the conclusion that an outline contour superimposed on an opaque surface causes this surface to emerge as a transparent layer when the luminances of the contour and the surface differ, in absolute value, by no more than 13.2 cd m−2. We have named this phenomenon ‘transparency of the intercepted surface’, to distinguish it from the phenomenal transparency arising when the contour and surface are very different in luminance. When such a difference exists, the contour acts as a factor of surface definition and grouping: the portion of the homogeneous surface it bounds emerges as a fourth surface and groups with a nearby surface if there is one close in luminance. The transparency phenomena (‘transparency of the contoured surface’) perceived in this context conform to the constraints of Metelli's model, as demonstrated by a second experiment, designed to gather ‘opacity’ ratings of stimuli. The observer judgments conformed to the values predicted by Metelli's formula for perceived degree of transparency, a. The role of the outline contour in conveying figural and intensity information is discussed.
48
Puil, E., B. Gimbarzevsky, and I. Spigelman. "Primary involvement of K+ conductance in membrane resonance of trigeminal root ganglion neurons." Journal of Neurophysiology 59, no. 1 (January 1, 1988): 77–89. http://dx.doi.org/10.1152/jn.1988.59.1.77.
Full textAbstract:
1. The complex impedances and impedance magnitude functions were obtained from neurons in in vitro slices of trigeminal root ganglia using frequency-domain analyses of intracellularly recorded voltage responses to specified oscillatory input currents. A neuronal model derived from linearized Hodgkin-Huxley-like equations was used to fit the complex impedance data. This procedure yielded estimates for membrane electrical properties. 2. Membrane resonance was observed in the impedance magnitude functions of all investigated neurons at their initial resting membrane potentials and was similar to that reported previously for trigeminal root ganglion neurons in vivo. Tetrodotoxin (10(-6) M), a Na+-channel blocker, applied in the bathing medium for 20 min produced only minor changes, if any, in the resonance, although gross impairment of Na+-spike electrogenesis was apparent in most of the neurons. Brief applications (1-5 min) of a K+-channel blocker, tetraethylammonium (TEA; 10(-2) M), increased the impedance magnitude and abolished, in a reversible manner, the resonant behavior. In all cases, the resonant frequency was decreased by TEA administration prior to total blockade of resonance. 3. The TEA-induced blockade of resonance was associated with decreases in the estimates of the membrane conductances, without significant alterations of input capacitance. A particularly large decrease was observed in Gr, the time-invariant resting conductance that includes a lumped leak conductance component. The voltage- and time-dependent conductance, GL, and associated relaxation time constant, tau u, also declined progressively during administration of TEA. 4. Systematic variations in the membrane potentials of trigeminal root ganglion neurons were produced by intracellular injections of long-lasting step currents with superposition of the oscillatory current stimuli, in order to assess the effects of TEA on the relationship of the electrical properties to the membrane potential. Applications of TEA led to a depolarizing shift in the dependence of the membrane property estimates, suggesting voltage-dependence of the effects of TEA on presumed K+ channels in the membrane. 5. These data suggest a primary involvement of K+ conductance in the genesis of membrane resonance. This electrical behavior or its ionic mechanism is a major modulator of the subthreshold electrical responsiveness of trigeminal root ganglion neurons.
49
Zemková, Erika, Alena Cepková, and José M. Muyor. "The association of reactive balance control and spinal curvature under lumbar muscle fatigue." PeerJ 9 (August 10, 2021): e11969. http://dx.doi.org/10.7717/peerj.11969.
Full textAbstract:
Background Although low back fatigue is an important intervening factor for physical functioning among sedentary people, little is known about its possible significance in relation to the spinal posture and compensatory postural responses to unpredictable stimuli. This study investigates the effect of lumbar muscle fatigue on spinal curvature and reactive balance control in response to externally induced perturbations. Methods A group of 38 young sedentary individuals underwent a perturbation-based balance test by applying a 2 kg load release. Sagittal spinal curvature and pelvic tilt was measured in both a normal and Matthiass standing posture both with and without a hand-held 2 kg load, and before and after the Sørensen fatigue test. Results Both the peak anterior and peak posterior center of pressure (CoP) displacements and the corresponding time to peak anterior and peak posterior CoP displacements significantly increased after the Sørensen fatigue test (all at p < 0.001). A lumbar muscle fatigue led to a decrease of the lumbar lordosis in the Matthiass posture while holding a 2 kg load in front of the body when compared to pre-fatigue conditions both without a load (p = 0.011, d = 0.35) and with a 2 kg load (p = 0.000, d = 0.51). Also the sacral inclination in the Matthiass posture with a 2 kg additional load significantly decreased under fatigue when compared to all postures in pre-fatigue conditions (p = 0.01, d = 0.48). Contrary to pre-fatigue conditions, variables of the perturbation-based balance test were closely associated with those of lumbar curvature while standing in the Matthiass posture with a 2 kg additional load after the Sørensen fatigue test (r values in range from −0.520 to −0.631, all at p < 0.05). Conclusion These findings indicate that lumbar muscle fatigue causes changes in the lumbar spinal curvature and this is functionally relevant in explaining the impaired ability to maintain balance after externally induced perturbations. This emphasizes the importance for assessing both spinal posture and reactive balance control under fatigue in order to reveal their interrelations in young sedentary adults and predict any significant deterioration in later years.
50
Yamaguchi, Masafumi, Kingo Fujimura, Hirokazu Kanegane, Hanae Toga-Yamaguchi, and Naoki Okamura. "Knockdown of Shwachman-Diamond Syndrome Gene, SBDS, Induces Increased Expression of Galectin-1 and Impaired Cell Growth." Blood 120, no. 21 (November 16, 2012): 2360. http://dx.doi.org/10.1182/blood.v120.21.2360.2360.
Full textAbstract:
Abstract Abstract 2360 Shwachman-Diamond syndrome (SDS) is an autosomal-recessive disorder characterized by exocrine pancreatic insufficiency and bone marrow failure. The SDS disease locus was mapped to chromosome 7q11. We have previously reported the Shwachman-Bodian-Diamond syndrome (SBDS) gene is not required for neutrophil maturation. However, SBDS knockdown cells which established by SBDS shRNAi were sensitive to apoptotic stimuli, and led to growth inhibition, indicating that SBDS acts to maintain survival of granulocyte precursor cells (Exp Hematol 35;579,2007). The precise mechanism by which the loss of SBDS inhibits growth of cells remains elusive. In order to clarify the impaired cell growth of SBDS knockdown cells, we analyzed two SDS patients (c.183_184TA>CT and c.258+2T>C) derived EB virus transformed lymphoblast cells (LCL). The growth of both LCL-SDS cell lines was considerably lower than control donor cells (LCL-C) which occurred in within 3 days of culture (1.4×106 cells/ml in LCL-C vs 5×105 cells/lm in LCL-SDS). LCL-C cells divided until 5 days, however, growth of LCL-SDS cells was saturated in 3days. When LCL-SDS cells were seeded to the fresh medium, LCL-SDS cells proliferated again. Conditional medium from 5 days SDS-LCL cell culture was then added to the culture of both LCL-C and LCL-SDS cell. This LCL-SDS conditional medium inhibited both LCL-C and LCL-SDS cell growth (50% and 60%, respectively), suggesting that growth inhibitors were secreted from LCL-SDS cells. In order to find growth inhibitors, we performed differential display. By annealing control primer based GeneFishing PCR screening, we found galectin-1 mRNA level was increased in LCL-SDS cells. We also confirmed that Galectin-1(Gal1) protein expression was markedly increased in LCL-SDS cells by western blot and conforcal microscopy. Gal1 was found to membrane bound, and it is plausible that Gal1 was secreted to the medium. In order to isolate Gal1 protein from medium, medium was passed through lactose agarose. Gal1 protein was purified from LCL-SDS cell culture medium, not from LCL-C cells. The inhibitory effect of Gal1 was confirmed using recombinant human Galectin-1 (rhGal1), which had similar dynamics to that of conditional medium from LCL-SDS cells. rhGal1 the proliferation of both LCL-C and LCL-SDS cells in a dose dependent manner. After exposure to rhGal1, Annexin V positive cells were increased in LCL-C cells (13.78±2.09% in control vs 16.83±2.81% in rhGal1, p=0.02). However, there was no difference in Gal1 induced apoptosis between LCL-C and LCL-SDS cells. In order to rescue growth failure of LCL-SDS cells, lactose, which modulates the binding between galectin and its substrate, was supplemented to the medium. Though lactose showed the growth inhibition of LCL cells, the viability of LCL-SDS cells was much higher than LCL-C cells. LCL-SDS cells were easily aggregated, however, the colony of LCL-SDS cell was much smaller in the presence of lactose. We also confirmed that Gal1 protein was overexpressed in SBDS knockdown 32Dcl3 cells, which were established by SBDS shRNAi. Conclusion: Overexpressed Gal1 was found from SDS patient's derived LCL cells and SBDS shRNAi knockdown 32Dcl3 cells. Gal1 was also found in the conditional medium of LCL-SBDS cells, and secreted Gal1 inhibited the cell proliferation. These results indicated that Galectin-1 partially involved in growth failure of SBDS deficient cells. Disclosures: No relevant conflicts of interest to declare.