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Journal articles on the topic 'Activation threshold hypothesis'

Author: Grafiati

Published: 4 June 2021

Last updated: 17 February 2022

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1

Latash, Mark, Mindy Levin, John Scholz, and Gregor Schöner. "Motor control theories and their applications." Medicina 46, no. 6 (2010): 382. http://dx.doi.org/10.3390/medicina46060054.

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We describe several infl uential hypotheses in the field of motor control including the equilibrium-point (referent confi guration) hypothesis, the uncontrolled manifold hypothesis, and the idea of synergies based on the principle of motor abundance. The equilibrium-point hypothesis is based on the idea of control with thresholds for activation of neuronal pools; it provides a framework for analysis of both voluntary and involuntary movements. In particular, control of a single muscle can be adequately described with changes in the threshold of motor unit recruitment during slow muscle stretch

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2

Qin, Chunhua, Amy G. Aslamkhan, Kara Pearson, et al. "AhR Activation in Pharmaceutical Development: Applying Liver Gene Expression Biomarker Thresholds to Identify Doses Associated With Tumorigenic Risks in Rats." Toxicological Sciences 171, no. 1 (2019): 46–55. http://dx.doi.org/10.1093/toxsci/kfz125.

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Abstract Aryl hydrocarbon receptor (AhR) activation is associated with carcinogenicity of non-genotoxic AhR-activating carcinogens such as 2,3,7,8-tetrachlorodibenzodioxin (TCDD), and is often observed with drug candidate molecules in development and raises safety concerns. As downstream effectors of AhR signaling, the expression and activity of Cyp1a1 and Cyp1a2 genes are commonly monitored as evidence of AhR activation to inform carcinogenic risk of compounds in question. However, many marketed drugs and phytochemicals are reported to induce these Cyps modestly and are not associated with di

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3

Purmohammad, Mehdi. "Linguistic alignment in L1–L2 dialogue." Language and Dialogue 5, no. 2 (2015): 312–33. http://dx.doi.org/10.1075/ld.5.2.07pur.

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The aim of this paper is to investigate alignment in L1–L2 dialogue. More specifically, I examine to what extent alignment in L1–L2 is different from alignment in L1–L1 dialogue. I investigate different variables that may affect linguistic alignment in the course of L1–L2 dialogue. As more variables, such as differences in language proficiency of interlocutors, affect the linguistic alignment in L1–L2 dialogue, it appears that linguistic alignment in L1–L2 dialogue is different from linguistic alignment in L1–L1 dialogue both quantitatively and quantitatively. I also discuss the mechanisms tha

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Ning, Xue-Han, Shi-Han Chen, Norman E. Buroker та ін. "Short-cycle hypoxia in the intact heart: hypoxia-inducible factor 1α signaling and the relationship to injury threshold". American Journal of Physiology-Heart and Circulatory Physiology 292, № 1 (2007): H333—H341. http://dx.doi.org/10.1152/ajpheart.00078.2006.

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Hypoxia-inducible factor 1α (HIF-1α) transcriptionally activates multiple genes, which regulate metabolic cardioprotective and cross-adaptive mechanisms. Hypoxia and several other stimuli induce the HIF-1α signaling cascade, although little data exist regarding the stress threshold for activation in heart. We tested the hypothesis that relatively mild short-cycle hypoxia, which produces minimal cardiac dysfunction and no sustained or major disruption in energy state, can induce HIF-1α activation. We developed a short-cycle hypoxia protocol in isolated perfused rabbit heart to test this hypothe

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Nagano-Saito, Atsuko, Paul Cisek, Andrea S. Perna, et al. "From anticipation to action, the role of dopamine in perceptual decision making: an fMRI-tyrosine depletion study." Journal of Neurophysiology 108, no. 2 (2012): 501–12. http://dx.doi.org/10.1152/jn.00592.2011.

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During simple sensorimotor decision making, neurons in the parietal cortex extract evidence from sensory information provided by visual areas until a decision is reached. Contextual information can bias parietal activity during the task and change the decision-making parameters. One type of contextual information is the availability of reward for correct decisions. We tested the hypothesis that the frontal lobes and basal ganglia use contextual information to bias decision making to maximize reward. Human volunteers underwent functional MRI while making decisions about the motion of dots on a

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Chua, M., and A. F. Dulhunty. "Noninactivating tension in rat skeletal muscle. Effects of thyroid hormone." Journal of General Physiology 94, no. 1 (1989): 183–203. http://dx.doi.org/10.1085/jgp.94.1.183.

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Inactivation of excitation-contraction coupling was examined in extensor digitorum longus (EDL) and soleus muscle fibers from rats injected daily with tri-iodothyronine (T3, 150 micrograms/kg) for 10-14 d. Steady-state activation and inactivation curves for contraction were obtained from measurements of peak potassium contracture tension at different surface membrane potentials. The experiments tested the hypothesis that noninactivating tension is a "window" tension caused by the overlap of the activation and inactivation curves. Changes in the amplitude and voltage dependence of noninactivati

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Porcellini, Simona, Elisabetta Traggiai, Ursula Schenk, et al. "Regulation of peripheral T cell activation by calreticulin." Journal of Experimental Medicine 203, no. 2 (2006): 461–71. http://dx.doi.org/10.1084/jem.20051519.

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Regulated expression of positive and negative regulatory factors controls the extent and duration of T cell adaptive immune response preserving the organism's integrity. Calreticulin (CRT) is a major Ca2+ buffering chaperone in the lumen of the endoplasmic reticulum. Here we investigated the impact of CRT deficiency on T cell function in immunodeficient mice reconstituted with fetal liver crt−/− hemopoietic progenitors. These chimeric mice displayed severe immunopathological traits, which correlated with a lower threshold of T cell receptor (TCR) activation and exaggerated peripheral T cell re

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8

Dotan, Raffy, Cameron Mitchell, Rotem Cohen, Panagiota Klentrou, David Gabriel, and Bareket Falk. "Child—Adult Differences in Muscle Activation — A Review." Pediatric Exercise Science 24, no. 1 (2012): 2–21. http://dx.doi.org/10.1123/pes.24.1.2.

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Children differ from adults in many muscular performance attributes such as size-normalized strength and power, endurance, fatigability and the recovery from exhaustive exercise, to name just a few. Metabolic attributes, such as glycolytic capacity, substrate utilization, and VO2 kinetics also differ markedly between children and adults. Various factors, such as dimensionality, intramuscular synchronization, agonist-antagonist coactivation, level of volitional activation, or muscle composition, can explain some, but not all of the observed differences. It is hypothesized that, compared with ad

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9

Hollowell, D. E., P. R. Bhandary, A. W. Funsten, and P. M. Suratt. "Respiratory-related recruitment of the masseter: response to hypercapnia and loading." Journal of Applied Physiology 70, no. 6 (1991): 2508–13. http://dx.doi.org/10.1152/jappl.1991.70.6.2508.

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To test the hypothesis that a muscle that closes the jaw, the masseter, can be recruited by ventilatory stimuli, we studied the electromyographic activation of the masseter and genioglossus in seven normal awake males who were exposed in random order to progressive hyperoxic hypercapnia, inspiratory threshold loading (-40 cmH2O), and combined hypercapnia and loading. With hypercapnia, the masseter was generally recruited after the genioglossus had been activated. Once recruited, activation of both muscles increased linearly with increasing CO2. Combined hypercapnia and loading produced more ac

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Baranov, Sergei V., Oxana V. Baranova, Svitlana Yablonska, et al. "Mitochondria modulate programmed neuritic retraction." Proceedings of the National Academy of Sciences 116, no. 2 (2018): 650–59. http://dx.doi.org/10.1073/pnas.1811021116.

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Neuritic retraction in the absence of overt neuronal death is a shared feature of normal aging and neurodegenerative disorders, but the intracellular mechanisms modulating this process are not understood. We propose that cumulative distal mitochondrial protein damage results in impaired protein import, leading to mitochondrial dysfunction and focal activation of the canonical apoptosis pathway in neurites. This is a controlled process that may not lead to neuronal death and, thus, we term this phenomenon “neuritosis.” Consistent with our hypothesis, we show that in primary cerebrocortical neur

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11

Maley, Carlo C., and Stephen J. Tapscott. "Selective Instability: Maternal Effort and the Evolution of Gene Activation and Deactivation Rates." Artificial Life 9, no. 3 (2003): 317–26. http://dx.doi.org/10.1162/106454603322392488.

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We previously used simulations of gene expression to demonstrate that rapid activation and deactivation rates stabilized outcomes in stochastic systems. We hypothesized that transient single allele inactivation of an autosomal gene during gametogenesis or very early embryogenesis could have a selective advantage if it permits the functional sampling of each allele and precludes committing maternal effort to an embryo with a deleterious mutation. To test this hypothesis, we simulated the evolution of gene expression activation and deactivation rates and imposed two different selective pressures

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Govardovskii, Victor I., Luba A. Astakhova, Alexander Yu Rotov, and Michael L. Firsov. "Rejection of the biophoton hypothesis on the origin of photoreceptor dark noise." Journal of General Physiology 151, no. 7 (2019): 887–97. http://dx.doi.org/10.1085/jgp.201812317.

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Rod photoreceptors of the vertebrate retina produce, in darkness, spontaneous discrete current waves virtually identical to responses to single photons. The waves comprise an irreducible source of noise (discrete dark noise) that may limit the threshold sensitivity of vision. The waves obviously originate from acts of random activation of single rhodopsin molecules. Until recently, it was generally accepted that the activation occurs due to the rhodopsin thermal motion. Yet, a few years ago it was proposed that rhodopsin molecules are activated not by heat but rather by real photons generated

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Yakovenko, Sergiy, Jan Kowalczewski, and Arthur Prochazka. "Intraspinal Stimulation Caudal to Spinal Cord Transections in Rats. Testing the Propriospinal Hypothesis." Journal of Neurophysiology 97, no. 3 (2007): 2570–74. http://dx.doi.org/10.1152/jn.00814.2006.

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Many laboratories have reported the successful regeneration of neurons across damaged portions of the spinal cord. Associated improvements in hindlimb locomotor movements have been attributed to the formation of functional neuronal connections with the locomotor central pattern generator (CPG). However, regenerating axons generally extend no more than 10 mm caudal to the lesion sites, terminating about 20 mm short of the lumbar segments thought to contain the CPG. It has therefore tacitly been assumed that the locomotor improvements arose from activation of propriospinal neurons relaying excit

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Burstein, Rami, Hiroyoshi Yamamura, Amy Malick, and Andrew M. Strassman. "Chemical Stimulation of the Intracranial Dura Induces Enhanced Responses to Facial Stimulation in Brain Stem Trigeminal Neurons." Journal of Neurophysiology 79, no. 2 (1998): 964–82. http://dx.doi.org/10.1152/jn.1998.79.2.964.

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Burstein, Rami, Hiroyoshi Yamamura, Amy Malick, and Andrew M. Strassman. Chemical stimulation of the intracranial dura induces enhanced responses to facial stimulation in brain stem trigeminal neurons. J. Neurophysiol. 79: 964–982, 1998. Chemical activation and sensitization of trigeminal primary afferent neurons innervating the intracranial meninges have been postulated as possible causes of certain headaches. This sensitization, however, cannot explain the extracranial hypersensitivity that often accompanies headache. The goal of this study was to test the hypothesis that chemical activation

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Chen, Zhengshan, Anna Hecht, and Markus Muschen. "Autoimmunity Checkpoints As Therapeutic Targets in B- and T-Cell Malignancies." Blood 130, Suppl_1 (2017): 718. http://dx.doi.org/10.1182/blood.v130.suppl_1.718.718.

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Abstract Background. Chronic active BCR or TCR signaling or its oncogenic mimics result in nuclear accumulation of NF-kB. Oncogenic mimicry of BCR- and TCR signaling can be induced by viral oncoproteins (e.g. LMP2A (EBV), K1 (KSHV) and Tax (HTLV1), activating mutations in the CD79A, CD79B and CD3Z signaling chains or genetic lesions driving tyrosine kinase (e.g. BCR-ABL1), ERK (RAS, BRAF, PLCG1) or PI3K (PIK3CA, PIK3R1) signaling. While BCR and TCR signaling induces positive selection, survival and proliferation in normal lymphocytes, the majority of B cell and T cell malignancies are driven b

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Zgonnikov, Arkady, Ihor Lubashevsky, Shigeru Kanemoto, Toru Miyazawa, and Takashi Suzuki. "To react or not to react? Intrinsic stochasticity of human control in virtual stick balancing." Journal of The Royal Society Interface 11, no. 99 (2014): 20140636. http://dx.doi.org/10.1098/rsif.2014.0636.

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Understanding how humans control unstable systems is central to many research problems, with applications ranging from quiet standing to aircraft landing. Increasingly, much evidence appears in favour of event-driven control hypothesis: human operators only start actively controlling the system when the discrepancy between the current and desired system states becomes large enough. The event-driven models based on the concept of threshold can explain many features of the experimentally observed dynamics. However, much still remains unclear about the dynamics of human-controlled systems, which

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Goto, Takahisa, Takashi Matsukawa, Daniel I. Sessler, et al. "Thermoregulatory Thresholds for Vasoconstriction in Patients Anesthetized with Various 1-Minimum Alveolar Concentration Combinations of Xenon, Nitrous Oxide, and Isoflurane." Anesthesiology 91, no. 3 (1999): 626. http://dx.doi.org/10.1097/00000542-199909000-00011.

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Background Nitrous oxide limits intraoperative hypothermia because the vasoconstriction threshold with nitrous oxide is higher than with equi-minimum alveolar concentrations of sevoflurane or isoflurane, presumably because of its stimulating actions on the sympathetic nervous system. Xenon, in contrast, does not cause sympathetic activation. Therefore, the authors tested the hypothesis that the vasoconstriction threshold during xenon-isoflurane anesthesia is less than during nitrous oxide-isoflurane anesthesia or isoflurane alone. Methods Fifteen patients each were randomly assigned to one of

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Koh, Hae-Young, and Klaudiusz R. Weiss. "Activity-Dependent Peptidergic Modulation of the Plateau-Generating Neuron B64 in the Feeding Network of Aplysia." Journal of Neurophysiology 97, no. 2 (2007): 1862–67. http://dx.doi.org/10.1152/jn.01230.2006.

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Many behaviors display various forms of activity-dependent plasticity. An example of such plasticity is the progressive shortening of the duration of protraction phase of feeding responses of Aplysia that occurs when feeding responses are repeatedly elicited. A similar protraction-duration shortening is observed in isolated ganglia of Aplysia when feeding-like motor programs are elicited through a prolonged stimulation of the command-like neuron CBI-2. Here, we investigate a cellular mechanism that may underlie this activity-dependent shortening of protraction duration of feeding motor program

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Warren, Emily B., Miles R. Bryan, Patricia Morcillo, Keisha N. Hardeman, Michael Aschner, and Aaron B. Bowman. "Manganese-induced Mitochondrial Dysfunction Is Not Detectable at Exposures Below the Acute Cytotoxic Threshold in Neuronal Cell Types." Toxicological Sciences 176, no. 2 (2020): 446–59. http://dx.doi.org/10.1093/toxsci/kfaa079.

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Abstract Manganese (Mn) is an essential metal, but excessive exposures have been well-documented to culminate in neurotoxicity. Curiously, the precise mechanisms of Mn neurotoxicity are still unknown. One hypothesis suggests that Mn exerts its toxicity by inhibiting mitochondrial function, which then (if exposure levels are high and long enough) leads to cell death. Here, we used a Huntington’s disease cell model with known differential sensitivities to manganese—STHdhQ7/Q7 and STHdhQ111/Q111 cells—to examine the effects of acute Mn exposure on mitochondrial function. We determined toxicity th

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Shapiro, Mark B., Gerald L. Gottlieb, Charity G. Moore, and Daniel M. Corcos. "Electromyographic Responses to an Unexpected Load in Fast Voluntary Movements: Descending Regulation of Segmental Reflexes." Journal of Neurophysiology 88, no. 2 (2002): 1059–63. http://dx.doi.org/10.1152/jn.2002.88.2.1059.

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This study examined the effects of unexpected loading on muscle activation during fast goal-oriented movements. We tested the hypothesis that the electromyographic (EMG) response to an unexpected load occurs at a short latency after the difference between the expected and the unexpected movement velocity exceeds a fixed threshold. Subjects performed two movement tasks as follows: 1) 30° fast elbow flexion movement with an inertial load added by a torque motor; and 2) 50° fast elbow flexion movement with no added load. These movement tasks were chosen to have similar timing parameters, such as

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Strafella, A., P. Ashby, A. Lozano, and A. E. Lang. "Pallidotomy Increases Cortical Inhibition in Parkinson's Disease." Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 24, no. 2 (1997): 133–36. http://dx.doi.org/10.1017/s0317167100021466.

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ABSTRACT:Background:Pallidotomy helps parkinsonian symptoms. We tested the hypothesis that this might be due to changes in inhibition in the motor cortex.Methods:We examined 15 patients with parkinsonism before and after posteroventral pallidotomy. Magnetic stimuli were delivered over the motor cortex, while subjects maintained a 30% maximum voluntary contraction of the contralateral first dorsal interosseus (FDI).Results:Weak stimuli inhibited voluntary muscle activity, while slightly stronger stimuli caused short latency facilitation from activation of the corticospinal neurons. After pallid

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Puri, B. K., N. J. Davey, P. H. Ellaway, and S. W. Lewis. "An Investigation of Motor Function in Schizophrenia using Transcranial Magnetic Stimulation of the Motor Cortex." British Journal of Psychiatry 169, no. 6 (1996): 690–95. http://dx.doi.org/10.1192/bjp.169.6.690.

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BackgroundIn this first investigation of motor function in schizophrenia using transcranial magnetic stimulation (TMS), the general hypothesis tested was that this methodology could be used to investigate the disruption of corticospinal inhibitory processes suggested by cognitive and psychophysiological paradigms.MethodNine drug-free DSM–IV schizophrenic patients were compared with nine age- and sex-matched normal subjects. Electromyographic (EMG) recordings were made from the thenar muscles of the dominant hand during sustained, weak voluntary contraction. TMS over a particular threshold appl

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Fill, M. D., and P. M. Best. "Contractile activation and recovery in skinned frog muscle stimulated by ionic substitution." American Journal of Physiology-Cell Physiology 254, no. 1 (1988): C107—C114. http://dx.doi.org/10.1152/ajpcell.1988.254.1.c107.

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Contractile activation of skinned (sarcolemma removed) skeletal muscle fibers stimulated by ionic substitution has been studied. Stimulating solutions contained varying amounts of Cl- and K+ with the [K+] x [Cl-] product kept constant at 368 mM2. Activation is a graded function of the ionic content of the stimulating solution. Mechanical threshold is reached when the [Cl-] is changed from 4 to 6.5 mM. Maximal activation occurs at 20 mM Cl-. After stimulation, fibers do not respond to a second stimulus unless allowed to recover. Contractile height reaches 50% of control levels after 30 s in the

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Ru, F., L. Surdenikova, M. Brozmanova, and M. Kollarik. "Adenosine-induced activation of esophageal nociceptors." American Journal of Physiology-Gastrointestinal and Liver Physiology 300, no. 3 (2011): G485—G493. http://dx.doi.org/10.1152/ajpgi.00361.2010.

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Clinical studies implicate adenosine acting on esophageal nociceptive pathways in the pathogenesis of noncardiac chest pain originating from the esophagus. However, the effect of adenosine on esophageal afferent nerve subtypes is incompletely understood. We addressed the hypothesis that adenosine selectively activates esophageal nociceptors. Whole cell perforated patch-clamp recordings and single-cell RT-PCR analysis were performed on the primary afferent neurons retrogradely labeled from the esophagus in the guinea pig. Extracellular recordings were made from the isolated innervated esophagus

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Sayer, R. J., A. M. Brown, P. C. Schwindt, and W. E. Crill. "Calcium currents in acutely isolated human neocortical neurons." Journal of Neurophysiology 69, no. 5 (1993): 1596–606. http://dx.doi.org/10.1152/jn.1993.69.5.1596.

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1. Ca2+ currents were investigated in neurons acutely isolated from adult human temporal neocortex. The aim was to compare the basic characteristics of the currents with those previously described in animals and to examine the effects of dihydropyridine Ca2+ antagonists and antiepileptic drugs. The tissue, obtained from patients undergoing temporal lobe surgery for medically intractable epilepsy, was sliced, incubated in papain, and triturated. 2. Most of the isolated neurons (34 of 36) were judged to be pyramidal cells by their morphology. Whole-cell voltage-clamp recordings revealed two comp

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Willis, Adam M., Bernard J. Slater, Ekaterina D. Gribkova, and Daniel A. Llano. "Open-loop organization of thalamic reticular nucleus and dorsal thalamus: a computational model." Journal of Neurophysiology 114, no. 4 (2015): 2353–67. http://dx.doi.org/10.1152/jn.00926.2014.

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The thalamic reticular nucleus (TRN) is a shell of GABAergic neurons that surrounds the dorsal thalamus. Previous work has shown that TRN neurons send GABAergic projections to thalamocortical (TC) cells to form reciprocal, closed-loop circuits. This has led to the hypothesis that the TRN is responsible for oscillatory phenomena, such as sleep spindles and absence seizures. However, there is emerging evidence that open-loop circuits are also found between TRN and TC cells. The implications of open-loop configurations are not yet known, particularly when they include time-dependent nonlinearitie

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Bourien, Jérôme, Yong Tang, Charlène Batrel, et al. "Contribution of auditory nerve fibers to compound action potential of the auditory nerve." Journal of Neurophysiology 112, no. 5 (2014): 1025–39. http://dx.doi.org/10.1152/jn.00738.2013.

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Sound-evoked compound action potential (CAP), which captures the synchronous activation of the auditory nerve fibers (ANFs), is commonly used to probe deafness in experimental and clinical settings. All ANFs are believed to contribute to CAP threshold and amplitude: low sound pressure levels activate the high-spontaneous rate (SR) fibers, and increasing levels gradually recruit medium- and then low-SR fibers. In this study, we quantitatively analyze the contribution of the ANFs to CAP 6 days after 30-min infusion of ouabain into the round window niche. Anatomic examination showed a progressive

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Haitas, Niobe, Mahnoush Amiri, Maximiliano Wilson, Yves Joanette, and Jason Steffener. "Age-preserved semantic memory and the CRUNCH effect manifested as differential semantic control networks: An fMRI study." PLOS ONE 16, no. 6 (2021): e0249948. http://dx.doi.org/10.1371/journal.pone.0249948.

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Semantic memory representations are overall well-maintained in aging whereas semantic control is thought to be more affected. To explain this phenomenon, this study aims to test the predictions of the Compensation Related Utilization of Neural Circuits Hypothesis (CRUNCH) focusing on task demands in aging as a possible framework. The CRUNCH effect would manifest itself in semantic tasks through a compensatory increase in neural activation in semantic control network regions but only up to a certain threshold of task demands. This study will compare 40 young (20–35 years old) with 40 older part

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Carlsson, Christer. "Acupuncture Mechanisms for Clinically Relevant Long-Term Effects – Reconsideration and a Hypothesis." Acupuncture in Medicine 20, no. 2-3 (2002): 82–99. http://dx.doi.org/10.1136/aim.20.2-3.82.

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From the author's direct involvement in clinical research, the conclusion has been drawn that clinically relevant long-term pain relieving effects of acupuncture (>6 months) can be seen in a proportion of patients with nociceptive pain. The mechanisms behind such effects are considered in this paper. From the existing experimental data some important conclusions can be drawn: Much of the animal research only represents short-term hypoalgesia probably induced by the mechanisms behind stress-induced analgesia (SIA) and the activation of diffuse noxious inhibitory control (DNIC). Almost all ex

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Friston, K. J., C. D. Frith, P. F. Liddle, and R. S. J. Frackowiak. "Comparing Functional (PET) Images: The Assessment of Significant Change." Journal of Cerebral Blood Flow & Metabolism 11, no. 4 (1991): 690–99. http://dx.doi.org/10.1038/jcbfm.1991.122.

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Statistical parametric maps (SPMs) are potentially powerful ways of localizing differences in regional cerebral activity. This potential is limited by uncertainties in assessing the significance of these maps. In this report, we describe an approach that may partially resolve this issue. A distinction is made between using SPMs as images of change significance and using them to identify foci of significant change. In the first case, the SPM can be reported nonselectively as a single mathematical object with its omnibus significance. Alternatively, the SPM constitutes a large number of repeated

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Westgaard, RH. "Muscle Activity as a Releasing Factor for Pain in the Shoulder and Neck." Cephalalgia 19, no. 25_suppl (1999): 1–8. http://dx.doi.org/10.1177/0333102499019s2501.

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In this review, the evidence for trapezius muscle activity as a releasing factor for shoulder and neck pain is considered, mainly on the basis of studies in our laboratory. Two lines of evidence are produced, (i) vocational studies in an occupational setting, where muscle activity pattern is recorded by surface EMG and a clinical examination of the shoulder region of the subjects performed; and (ii) laboratory studies where muscle activity patterns and pain development are recorded in an experimental situation with mental stress and minimal physical activity. The vocational studies demonstrate

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Morélot-Panzini, Capucine, Alexandre Demoule, Christian Straus, et al. "Dyspnea as a Noxious Sensation: Inspiratory Threshold Loading May Trigger Diffuse Noxious Inhibitory Controls in Humans." Journal of Neurophysiology 97, no. 2 (2007): 1396–404. http://dx.doi.org/10.1152/jn.00116.2006.

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Dyspnea, a leading respiratory symptom, shares many clinical, physiological, and psychological features with pain. Both activate similar brain areas. The neural mechanisms of dyspnea are less well described than those of pain. The present research tested the hypothesis of common pathways between the two sensations. Six healthy men (age 30–40 yr) were studied. The spinal nociceptive flexion reflex (RIII) was first established in response to electrical sural stimulation. Dyspnea was then induced through inspiratory threshold loading, forcing the subjects to develop 70% of their maximal inspirato

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Duncan, R. L., and K. A. Hruska. "Chronic, intermittent loading alters mechanosensitive channel characteristics in osteoblast-like cells." American Journal of Physiology-Renal Physiology 267, no. 6 (1994): F909—F916. http://dx.doi.org/10.1152/ajprenal.1994.267.6.f909.

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The effects of chronic, intermittent strain on the mechanosensitive cation (SA-cat) channels in UMR-106.01 osteoblast-like osteosarcoma cells were studied using patch-clamp techniques. Chronically strained cells demonstrated significantly larger increases in whole cell conductance when subjected to additional mechanical strain than nonstrained controls (69.0 +/- 15.1 vs. 14.1 +/- 3.1%; P < 0.001). This increase could be blocked by the SA-cat channel inhibitor, gadolinium, and corresponded to a three- to fivefold increase in SA-cat channel activity. Chronic strain increased the number of ope

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Chen, Shih-Pin, Tao Qin, Jessica L. Seidel, et al. "Inhibition of the P2X7–PANX1 complex suppresses spreading depolarization and neuroinflammation." Brain 140, no. 6 (2017): 1643–56. http://dx.doi.org/10.1093/brain/awx085.

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Abstract Spreading depolarization is a wave of neuronal and glial depolarization. Within minutes after spreading depolarization, the neuronal hemichannel pannexin 1 (PANX1) opens and forms a pore complex with the ligand-gated cation channel P2X7, allowing the release of excitatory neurotransmitters to sustain spreading depolarization and activate neuroinflammation. Here, we explore the hypothesis that the P2X7–PANX1 pore complex is a critical determinant of spreading depolarization susceptibility with important consequences for neuroinflammation and trigeminovascular activation. We found that

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Célèrier, Evelyne, Cyril Rivat, Yan Jun, et al. "Long-lasting Hyperalgesia Induced by Fentanyl in Rats." Anesthesiology 92, no. 2 (2000): 465. http://dx.doi.org/10.1097/00000542-200002000-00029.

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Background It has been reported that mu-opioid receptor activation leads to a sustained increase in glutamate synaptic effectiveness at the N-methyl-D-aspartate (NMDA) receptor level, a system associated with central hypersensitivity to pain. One hypothesis is that postoperative pain may result partly from the activation of NMDA pain facilitatory processes induced by opiate treatment per se. The authors tested here the effectiveness of the opiate analgesic fentanyl for eliciting a delayed enhancement in pain sensitivity. Methods The consequences of four bolus injections (every 15 min) of fenta

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Liu, Ying, Anna Kamitakahara, Alice Joohee Kim, and Greti Aguilera. "Cyclic Adenosine 3′,5′-Monophosphate Responsive Element Binding Protein Phosphorylation Is Required But Not Sufficient for Activation of Corticotropin-Releasing Hormone Transcription." Endocrinology 149, no. 7 (2008): 3512–20. http://dx.doi.org/10.1210/en.2008-0052.

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cAMP is a major regulator of CRH transcription. However, receptors activating CRH neurons (α-adrenergic and glutamatergic) do not signal through cAMP, suggesting that calcium phospholipid-dependent signaling synergizes with small elevations of intracellular cAMP. To test this hypothesis, we examined the relationship between activation of CRH transcription, cAMP production, and cAMP response element binding protein (CREB) phosphorylation in neuronal cultures treated with the adenylyl cyclase stimulator, forskolin, the phorbol ester, phorbol-12-myristate-13-acetate (PMA), or their combination. F

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Raux, Mathieu, Haiqun Xie, Thomas Similowski, and Lisa Koski. "Facilitatory conditioning of the supplementary motor area in humans enhances the corticophrenic responsiveness to transcranial magnetic stimulation." Journal of Applied Physiology 108, no. 1 (2010): 39–46. http://dx.doi.org/10.1152/japplphysiol.91454.2008.

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Inspiratory loading in awake humans is associated with electroencephalographic signs of supplementary motor area (SMA) activation. To provide evidence for a functional connection between SMA and the diaphragm representation in the primary motor cortex (M1DIA), we tested the hypothesis that modulating SMA activity using repetitive transcranial magnetic stimulation (rTMS) would alter M1DIA excitability. Amplitude and latency of diaphragm motor evoked potentials (MEPDIA), evoked through single pulse M1DIA stimulation, before and up to 16 min after SMA stimulation, were taken as indicators of M1DI

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Ruehland, Warren R., Peter D. Rochford, Robert J. Pierce, et al. "Genioglossus muscle responses to resistive loads in severe OSA patients and healthy control subjects." Journal of Applied Physiology 127, no. 6 (2019): 1586–98. http://dx.doi.org/10.1152/japplphysiol.00186.2019.

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This study aimed to determine whether there is impairment of genioglossus neuromuscular responses to small negative pressure respiratory stimuli, close to the conscious detection threshold, in obstructive sleep apnea (OSA). We compared genioglossus electromyogram (EMGgg) responses to midinspiratory resistive loads of varying intensity (≈1.2–6.2 cmH2O·L−1·s), delivered via a nasal mask, between 16 severe OSA and 17 control participants while the subjects were awake and in a seated upright position. We examined the relationship between stimulus intensity and peak EMGgg amplitude in a 200-ms post

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Köhr, G., and I. Mody. "Endogenous intracellular calcium buffering and the activation/inactivation of HVA calcium currents in rat dentate gyrus granule cells." Journal of General Physiology 98, no. 5 (1991): 941–67. http://dx.doi.org/10.1085/jgp.98.5.941.

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Granule cells acutely dissociated from the dentate gyrus of adult rat brains displayed a single class of high-threshold, voltage-activated (HVA) Ca2+ channels. The kinetics of whole-cell Ca2+ currents recorded with pipette solutions containing an intracellular ATP regenerating system but devoid of exogenous Ca2+ buffers, were fit best by Hodgkin-Huxley kinetics (m2h), and were indistinguishable from those recorded with the nystatin perforated patch method. In the absence of exogenous Ca2+ buffers, inactivation of HVA Ca2+ channels was a predominantly Ca(2+)-dependent process. The contribution

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Eilers, Helge, Fiore Cattaruzza, Romina Nassini, et al. "Pungent General Anesthetics Activate Transient Receptor Potential-A1 to Produce Hyperalgesia and Neurogenic Bronchoconstriction." Anesthesiology 112, no. 6 (2010): 1452–63. http://dx.doi.org/10.1097/aln.0b013e3181d94e00.

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Background Volatile anesthetics such as isoflurane and halothane have been in clinical use for many years and represent the group of drugs most commonly used to maintain general anesthesia. However, despite their widespread use, the molecular mechanisms by which these drugs exert their effects are not completely understood. Recently, a seemingly paradoxical effect of general anesthetics has been identified: the activation of peripheral nociceptors by irritant anesthetics. This mechanism may explain the hyperalgesic actions of inhaled anesthetics and their adverse effects in the airways. Method

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Zhou, Gang, Zhengbin Lu, John D. McCadden, Hyam I. Levitsky, and Aimee L. Marson. "Reciprocal Changes in Tumor Antigenicity and Antigen-specific T Cell Function during Tumor Progression." Journal of Experimental Medicine 200, no. 12 (2004): 1581–92. http://dx.doi.org/10.1084/jem.20041240.

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Two seemingly incompatible models exist to explain the progression of cancers in immunocompetent hosts. The cancer immunosurveillance hypothesis posits that recognition of transformed cells by the immune system results in the generation of an effector response that may impede tumor growth. Clinically detectable cancer results from the emergence of tumor variants that escape this selective pressure. Alternatively, induction of immune tolerance to tumor antigens may enable cancer progression. We established a model where changes in the function of tumor-specific T cells and in tumor antigen expr

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Peterson, L. N., S. Mathur, and J. S. Borzecki. "Reset of the osmotic threshold for vasopressin in rats fed a low NaCl, K-free diet." Canadian Journal of Physiology and Pharmacology 70, no. 5 (1992): 645–50. http://dx.doi.org/10.1139/y92-082.

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Activation of the renin-angiotensin system induced by feeding a low NaCl, K-free (LS) diet is associated with polydipsia and a chronic reduction in effective plasma osmolality (efPosm). We have recently shown that converting enzyme inhibition with enalapril (EP) abolishes polydipsia. The present study was designed to test the hypothesis that the osmotic threshold for vasopressin is reset in rats fed the LS diet and to examine the effect of EP on ambient and osmotically stimulated plasma vasopressin levels (PAvp). Animals were fed the LS diet or a control salt diet and treated with vehicle or t

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Kalappa, Bopanna I., Lin Feng, William R. Kem, Alexander G. Gusev, and Victor V. Uteshev. "Mechanisms of facilitation of synaptic glutamate release by nicotinic agonists in the nucleus of the solitary tract." American Journal of Physiology-Cell Physiology 301, no. 2 (2011): C347—C361. http://dx.doi.org/10.1152/ajpcell.00473.2010.

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The nucleus of the solitary tract (NTS) is the principal integrating relay in the processing of visceral sensory information. Functional nicotinic acetylcholine receptors (nAChRs) have been found on presynaptic glutamatergic terminals in subsets of caudal NTS neurons. Activation of these receptors has been shown to enhance synaptic release of glutamate and thus may modulate autonomic sensory-motor integration and visceral reflexes. However, the mechanisms of nAChR-mediated facilitation of synaptic glutamate release in the caudal NTS remain elusive. This study uses rat horizontal brainstem slic

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Sun, Rui-Qing, Yi-Jun Tu, Nada B. Lawand, Jing-Yin Yan, Qing Lin, and William D. Willis. "Calcitonin Gene-Related Peptide Receptor Activation Produces PKA- and PKC-Dependent Mechanical Hyperalgesia and Central Sensitization." Journal of Neurophysiology 92, no. 5 (2004): 2859–66. http://dx.doi.org/10.1152/jn.00339.2004.

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Calcitonin gene-related peptide (CGRP), acting through CGRP receptors, produces behavioral signs of mechanical hyperalgesia in rats and sensitization of wide dynamic range (WDR) neurons in the spinal cord dorsal horn. Although involvement of CGRP receptors in central sensitization has been confirmed, the second-messenger systems activated by CGRP receptor stimulation and involved in pain transmission are not clear. This study tested whether the hyperalgesia and sensitizing effects of CGRP receptor activation on WDR neurons are mediated by protein kinase A or C (PKA or PKC) signaling. Intrathec

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Meeks, Melissa K., Marcia L. Ripley, Zhicheng Jin, and Christopher M. Rembold. "Heat shock protein 20-mediated force suppression in forskolin-relaxed swine carotid artery." American Journal of Physiology-Cell Physiology 288, no. 3 (2005): C633—C639. http://dx.doi.org/10.1152/ajpcell.00269.2004.

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Increases in cyclic nucleotide levels induce smooth muscle relaxation by deactivation [reductions in myosin regulatory light chain (MRLC) phosphorylation (e.g., by reduced [Ca2+])] or force suppression (reduction in force without reduction in MRLC phosphorylation). Ser16-heat shock protein 20 (HSP20) phosphorylation is the proposed mediator of force suppression. We evaluated three potential hypotheses whereby Ser16-HSP20 phosphorylation could regulate smooth muscle force: 1) a threshold level of HSP20 phosphorylation could inactivate a thin filament as a whole, 2) phosphorylation of a single H

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Barman, S. M., and G. L. Gebber. "Lateral tegmental field neurons of cat medulla: a source of basal activity of raphespinal sympathoinhibitory neurons." Journal of Neurophysiology 61, no. 5 (1989): 1011–24. http://dx.doi.org/10.1152/jn.1989.61.5.1011.

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1. We tested the hypothesis that sympathoinhibitory (SI) neurons in the lateral tegmental field (LTF) of the cat medulla exert their actions over a pathway that includes raphe neurons whose axons innervate the thoracic intermediolateral nucleus (IML). 2. We recorded from 32 LTF neurons with sympathetic nerve-related activity [as demonstrated with spike-triggered averaging of inferior cardiac sympathetic nerve discharge (SND)] whose firing rate increased during the inhibition of SND produced by baroreceptor reflex activation. These neurons were classified as SI in function. 3. Twenty-three of t

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Wilkinson, Marshall F., Tumul Chowdhury, W. Alan Mutch, and Anthony M. Kaufmann. "Analysis of facial motor evoked potentials for assessing a central mechanism in hemifacial spasm." Journal of Neurosurgery 126, no. 2 (2017): 379–85. http://dx.doi.org/10.3171/2016.2.jns151384.

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OBJECTIVE Hemifacial spasm (HFS) is a cranial nerve hyperactivity disorder characterized by unique neurophysiological features, although the underlying pathophysiology remains disputed. In this study, the authors compared the effects of desflurane on facial motor evoked potentials (MEPs) from the spasm and nonspasm sides of patients who were undergoing microvascular decompression (MVD) surgery to test the hypothesis that HFS is associated with a central elevation of facial motor neuron excitability. METHODS Facial MEPs were elicited in 31 patients who were undergoing MVD for HFS and were admin

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SCHMITT, ELENA. "When boundaries are crossed: Evaluating language attrition data from two perspectives." Bilingualism: Language and Cognition 13, no. 1 (2009): 63–72. http://dx.doi.org/10.1017/s1366728909990381.

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This study provides an account for a long-term selective loss of L1 (Russian) morpho-syntactic and content components in early immigrants to the U.S. The analysis of naturally occurring data is carried out from the perspective of two theoretical approaches – three models developed within language contact (Myers-Scotton 2002, 2005) and the Activation Threshold hypothesis as a component of a neurolinguistic approach to bilingualism (Paradis, 2004, 2007). The results show that the language contact approach is useful in identifying morpheme types that are most vulnerable to attrition. The second a

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Prenzler, Nils Kristian, Eugen Kludt, Thomas Giere, Rolf Salcher, Thomas Lenarz, and Hannes Maier. "Middle Ear Transducer: Long Term Stability of the Latest Generation T2." BioMed Research International 2019 (January 6, 2019): 1–6. http://dx.doi.org/10.1155/2019/4346325.

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Objectives/Hypothesis. Comparing long term stability of the Middle Ear Transducers (MET) of the 1st generation T1 (Otologics LLC) with the current generation T2 (Cochlear Ltd.) in all our clinical cases with standard incus coupling. Study Design. Retrospective chart review. Methods. 52 ears implanted with a MET device between 2008 and 2016 were analyzed retrospectively. All patients suffered from sensorineural hearing loss and the actuator was coupled to the body of the incus (standard coupling). 23 ears were implanted with the transducer T1 (Otologics LLC) between 2008 and 2011 and 29 ears we

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Cole, W. C., D. Chartier, M. Martin, and N. Leblanc. "Ca2+ permeation through Na+ channels in guinea pig ventricular myocytes." American Journal of Physiology-Heart and Circulatory Physiology 273, no. 1 (1997): H128—H137. http://dx.doi.org/10.1152/ajpheart.1997.273.1.h128.

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This study was undertaken to test the hypothesis that, in the absence of extracellular Na+, Ca2+ can permeate tetrodotoxin (TTX)-sensitive Na+ channels in Cs(+)-loaded whole cell voltage-clamped guinea pig ventricular myocytes (22-24 degrees C). With 10 mM extracellular Ca2+, 50-ms step depolarizations (-50 to +25 mV) from holding potentials of -100 or -80 mV elicited fast and slow types of inward current: 1) a small (< 400 pA) dihydropyridine-insensitive inward current that exhibited similar voltage dependence to that of Na+ channels, with an activation threshold and peak near -45 mV and -

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