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Academic literature on the topic 'Neurones sensitifs – Classification'
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Journal articles on the topic "Neurones sensitifs – Classification"
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Oliveira-Abreu, Klausen, Nathalia Silva-dos-Santos, Andrelina Coelho-de-Souza, Francisco Ferreira-da-Silva, Kerly Silva-Alves, Ana Cardoso-Teixeira, José Cipolla-Neto, and José Leal-Cardoso. "Melatonin Reduces Excitability in Dorsal Root Ganglia Neurons with Inflection on the Repolarization Phase of the Action Potential." International Journal of Molecular Sciences 20, no. 11 (May 28, 2019): 2611. http://dx.doi.org/10.3390/ijms20112611.
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Melatonin is a neurohormone produced and secreted at night by pineal gland. Many effects of melatonin have already been described, for example: Activation of potassium channels in the suprachiasmatic nucleus and inhibition of excitability of a sub-population of neurons of the dorsal root ganglia (DRG). The DRG is described as a structure with several neuronal populations. One classification, based on the repolarizing phase of the action potential (AP), divides DRG neurons into two types: Without (N0) and with (Ninf) inflection on the repolarization phase of the action potential. We have previously demonstrated that melatonin inhibits excitability in N0 neurons, and in the present work, we aimed to investigate the melatonin effects on the other neurons (Ninf) of the DRG neuronal population. This investigation was done using sharp microelectrode technique in the current clamp mode. Melatonin (0.01–1000.0 nM) showed inhibitory activity on neuronal excitability, which can be observed by the blockade of the AP and by the increase in rheobase. However, we observed that, while some neurons were sensitive to melatonin effect on excitability (excitability melatonin sensitive—EMS), other neurons were not sensitive to melatonin effect on excitability (excitability melatonin not sensitive—EMNS). Concerning the passive electrophysiological properties of the neurons, melatonin caused a hyperpolarization of the resting membrane potential in both cell types. Regarding the input resistance (Rin), melatonin did not change this parameter in the EMS cells, but increased its values in the EMNS cells. Melatonin also altered several AP parameters in EMS cells, the most conspicuously changed was the (dV/dt)max of AP depolarization, which is in coherence with melatonin effects on excitability. Otherwise, in EMNS cells, melatonin (0.1–1000.0 nM) induced no alteration of (dV/dt)max of AP depolarization. Thus, taking these data together, and the data of previous publication on melatonin effect on N0 neurons shows that this substance has a greater pharmacological potency on Ninf neurons. We suggest that melatonin has important physiological function related to Ninf neurons and this is likely to bear a potential relevant therapeutic use, since Ninf neurons are related to nociception.
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Warren, S., H. A. Hamalainen, and E. P. Gardner. "Objective classification of motion- and direction-sensitive neurons in primary somatosensory cortex of awake monkeys." Journal of Neurophysiology 56, no. 3 (September 1, 1986): 598–622. http://dx.doi.org/10.1152/jn.1986.56.3.598.
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In order to classify movement-sensitive neurons in SI cortex, and to estimate their relative distribution, we have developed a new simple method for controlled motion of textured surfaces across the skin, as well as a set of objective criteria for determining direction selectivity. Moving stimuli were generated using 5 mm thick precision gear wheels, whose teeth formed a grafting. They were mounted on the shafts of low-torque potentiometers (to measure the speed and direction of movement) and rolled manually across the skin using the potentiometer shaft as an axle. As the grafting wheel was advanced, its ridges sequentially contacted a specific set of points on the skin, leaving gaps of defined spacing that were unstimulated. This stimulus was reproducible from trial to trial and produced little distention of the skin. Three objective criteria were used to categorize responses: the ratio of responses to motion in the most and least preferred directions [direction index (DI)], the difference between mean firing rates in the two directions divided by the average standard deviation [index of discriminability (delta'e)], and statistical tests. Neurons were classified as direction sensitive if DI greater than 35, delta's greater than or equal to 1.35 (equivalent to 75% correct discrimination by an unbiased observer), and firing rates in most- and least-preferred directions were significantly different (P less than 0.05). Good agreement was found between the three classification schemes. Recordings were made from 1,020 cortical neurons in the hand and forearm regions of primary somatosensory cortex (areas 3b, 1 and 2) of five macaque monkeys. Tangential motion across the skin was found to be an extremely effective stimulus for SI cortical neurons. Two hundred eighty six of 757 tactile neurons (38%) responded more vigorously to moving stimuli than to pressure or tapping the skin. One hundred twenty-one cells were tested with moving gratings and were classified according to their ability to differentiate movement in longitudinal and transverse directions. Responses to the moving gratings resembled those observed when stroking the skin with brushed, edges, or blunt probes. Three major types of firing patterns were found: motion sensitive, direction sensitive, and orientation sensitive. Motion-sensitive neurons (37%) responded to movement in both longitudinal and transverse directions with only slight difference in firing rates and interval distributions. Responses throughout the field were fairly uniform, and no clear point of maximum sensitivity was apparent. Direction-sensitive neurons (60%) displayed clear preferences for movement in one or more directions.4
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Pastori, Valentina, Alessia D’Aloia, Stefania Blasa, and Marzia Lecchi. "Serum-deprived differentiated neuroblastoma F-11 cells express functional dorsal root ganglion neuron properties." PeerJ 7 (October 30, 2019): e7951. http://dx.doi.org/10.7717/peerj.7951.
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The isolation and culture of dorsal root ganglion (DRG) neurons cause adaptive changes in the expression and regulation of ion channels, with consequences on neuronal excitability. Considering that not all neurons survive the isolation and that DRG neurons are heterogeneous, it is difficult to find the cellular subtype of interest. For this reason, researchers opt for DRG-derived immortal cell lines to investigate endogenous properties. The F-11 cell line is a hybridoma of embryonic rat DRG neurons fused with the mouse neuroblastoma line N18TG2. In the proliferative condition, F-11 cells do not display a gene expression profile correspondent with specific subclasses of sensory neurons, but the most significant differences when compared with DRGs are the reduction of voltage-gated sodium, potassium and calcium channels, and the small amounts of TRPV1 transcripts. To investigate if functional properties of mature F-11 cells showed more similarities with those of isolated DRG neurons, we differentiated them by serum deprivation. Potassium and sodium currents significantly increased with differentiation, and biophysical properties of tetrodotoxin (TTX)-sensitive currents were similar to those characterized in small DRG neurons. The analysis of the voltage-dependence of calcium currents demonstrated the lack of low threshold activated components. The exclusive expression of high threshold activated Ca2+ currents and of TTX-sensitive Na+ currents correlated with the generation of a regular tonic electrical activity, which was recorded in the majority of the cells (80%) and was closely related to the activity of afferent TTX-sensitive A fibers of the proximal urethra and the bladder. Responses to capsaicin and substance P were also recorded in ~20% and ~80% of cells, respectively. The percentage of cells responsive to acetylcholine was consistent with the percentage referred for rat DRG primary neurons and cell electrical activity was modified by activation of non-NMDA receptors as for embryonic DRG neurons. These properties and the algesic profile (responses to pH5 and sensitivity to both ATP and capsaicin), proposed in literature to define a sub-classification of acutely dissociated rat DRG neurons, suggest that differentiated F-11 cells express receptors and ion channels that are also present in sensory neurons.
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Warren, S., H. A. Hamalainen, and E. P. Gardner. "Objective classification of motion- and direction-sensitive neurons in primary somatosensory cortex of awake monkeys." Journal of Neurophysiology 57, no. 1 (January 1, 1987): 1. http://dx.doi.org/10.1152/jn.1987.57.1.1-a.
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S. Warren, H. A. Hamalainen, and E. P. Gardner, “Objective classification of motion- and direction-sensitive neurons in primary somatosensory cortex of awake monkeys.” It was incorrectly stated that Orban and co-workers ( J. Neurophysiol. 45: 1059–1073, 1981) attributed direction selectivity to cortical neurons having a direction index (DI)≥20. Orban et al. actually used a weighted average of DIs and defined cells with a mean DI (MDI) above 50 as direction selective. Their criterion for direction selectivity was stricter and not less stringent, as stated in the paper. This error does not alter any of the data or conclusions of Warren et al.
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Warren, S., H. A. Hamalainen, and E. P. Gardner. "Objective classification of motion- and direction-sensitive neurons in primary somatosensory cortex of awake monkeys." Journal of Neurophysiology 57, no. 6 (June 1, 1987): 1. http://dx.doi.org/10.1152/jn.1987.57.6.1-a.
Full textAbstract:
S. Warren, H. A. Hamalainen, and E. P. Gardner, “Objective classification of motion- and direction-sensitive neurons in primary somatosensory cortex of awake monkeys.” It was incorrectly stated that Orban and co-workers(J. Neurophysiol. 45: 1059–1073, 1981) attributed direction selectivity to cortical neurons having a direction index (DI) ge 20. Orban et al. actually used a weighted average of DIs and defined cells with a mean DI (MDI) above 50 as direction selective. Their criterion for direction selectivity was stricter and not less stringent, as stated in the paper. This error does not alter any of the data or conclusions of Warren et al.
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Mohren, Thomas L., Thomas L. Daniel, Steven L. Brunton, and Bingni W. Brunton. "Neural-inspired sensors enable sparse, efficient classification of spatiotemporal data." Proceedings of the National Academy of Sciences 115, no. 42 (September 13, 2018): 10564–69. http://dx.doi.org/10.1073/pnas.1808909115.
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Sparse sensor placement is a central challenge in the efficient characterization of complex systems when the cost of acquiring and processing data is high. Leading sparse sensing methods typically exploit either spatial or temporal correlations, but rarely both. This work introduces a sparse sensor optimization that is designed to leverage the rich spatiotemporal coherence exhibited by many systems. Our approach is inspired by the remarkable performance of flying insects, which use a few embedded strain-sensitive neurons to achieve rapid and robust flight control despite large gust disturbances. Specifically, we identify neural-inspired sensors at a few key locations on a flapping wing that are able to detect body rotation. This task is particularly challenging as the rotational twisting mode is three orders of magnitude smaller than the flapping modes. We show that nonlinear filtering in time, built to mimic strain-sensitive neurons, is essential to detect rotation, whereas instantaneous measurements fail. Optimized sparse sensor placement results in efficient classification with approximately 10 sensors, achieving the same accuracy and noise robustness as full measurements consisting of hundreds of sensors. Sparse sensing with neural-inspired encoding establishes an alternative paradigm in hyperefficient, embodied sensing of spatiotemporal data and sheds light on principles of biological sensing for agile flight control.
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Campbell, Robert A. A., Jan W. H. Schnupp, Akhil Shial, and Andrew J. King. "Binaural-Level Functions in Ferret Auditory Cortex: Evidence for a Continuous Distribution of Response Properties." Journal of Neurophysiology 95, no. 6 (June 2006): 3742–55. http://dx.doi.org/10.1152/jn.01155.2005.
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Many previous studies have subdivided auditory neurons into a number of physiological classes according to various criteria applied to their binaural response properties. However, it is often unclear whether such classifications represent discrete classes of neurons or whether they merely reflect a potentially convenient but ultimately arbitrary partitioning of a continuous underlying distribution of response properties. In this study we recorded the binaural response properties of 310 units in the auditory cortex of anesthetized ferrets, using an extensive range of interaural level differences (ILDs) and average binaural levels (ABLs). Most recordings were from primary auditory fields on the middle ectosylvian gyrus and from neurons with characteristic frequencies >5 kHz. We used simple multivariate statistics to quantify a fundamental coding feature: the shapes of the binaural response functions. The shapes of all 310 binaural response surfaces were represented as points in a five-dimensional principal component space. This space captured the underlying shape of all the binaural response surfaces. The distribution of binaural level functions was not homogeneous because some shapes were more common than others. Despite this, clustering validation techniques revealed no evidence for the existence of discrete, or partially overlapping, clusters that could serve as a basis for an objective classification of binaural-level functions. We also examined the gradients of the response functions for the population of units; these gradients were greatest near the midline, which is consistent with free-field data showing that cortical neurons are most sensitive to changes in stimulus location in this region of space.
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Esteky, H., and H. D. Schwark. "Responses of rapidly adapting neurons in cat primary somatosensory cortex to constant-velocity mechanical stimulation." Journal of Neurophysiology 72, no. 5 (November 1, 1994): 2269–79. http://dx.doi.org/10.1152/jn.1994.72.5.2269.
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1. The responses of rapidly adapting (RA) neurons to constant-velocity ramp stimulation were studied in the forepaw representation of primary somatosensory cortex (SI) of anesthetized cats. Single probe stimuli were used to indent the skin or to move hair parallel to the skin surface. The velocity of the moving stimulus probe was varied to determine the rate sensitivity of the neurons. 2. The cortical RA neurons were classified into four categories identified as G1/F1, Gint/Fint, G2/F2, and complex classes. The primary bases for classification in the present experiments were the pattern of response during ramp stimulation, velocity threshold, and directional sensitivity. 3. Of the RA neurons recorded in SI, 84% (49/58) could be assigned to one of the three response classes with little ambiguity. The remaining neurons showed more complex responses. The form of the complex responses suggested that they arose from a combination of inputs of different response classes. Some of these appeared to arise from a combination of different RA input classes, whereas others had components that resembled responses previously described for C mechanoreceptors. 4. Increased ramp velocity resulted in increased average firing frequency in 87% of the RA neurons. This relationship, which could be fitted with a power function, varied with response class. G1/F1 neurons were more sensitive to stimulus rate than G2/F2 neurons. Significant differences between response classes also were seen in the relationship between ramp velocity and their number of evoked action potentials and in their spontaneous firing rates. 5. The results demonstrate that a discrete SI neuron population is sensitive to the rate of stimulus movement. This observation is consistent with psychophysical studies reporting effects of stimulus indentation rates on perception of single probe stimuli. The appearance of complex responses in a small proportion of SI neurons provides evidence of convergence in somatosensory pathways to SI.
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Chittajallu, Siva K., Mathew J. Palakal, and Donald Wong. "Analysis and classification of delay-sensitive cortical neurons based on response to temporal parameters in echolocation signals." Hearing Research 84, no. 1-2 (April 1995): 157–66. http://dx.doi.org/10.1016/0378-5955(95)00022-v.
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Cvijanovic, Milan, Miroslav Ilin, Petar Slankamenac, Sofija Banic-Horvat, and Zita Jovin. "The sensitivity of electromyoneurography in the diagnosis of diabetic polyneuropathy." Medical review 64, no. 1-2 (2011): 11–14. http://dx.doi.org/10.2298/mpns1102011c.
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Diabetic polyneuropathy is a complex set of clinical syndromes, which deplete various regions of the nervous system. The process leading to diabetic neuropathy is multi-factorial. Its symptoms are paresthesia, dysesthesia and pain. The signs of damage to the peripheral neurons are hypoesthesia, hypoalgesia, hyperesthesia and hyperalgesia, decreased tendon reflexes, and, possibly, weakness and muscle atrophy. There is no universal classification. Electromyoneurography is indispensable in the diagnosis of diabetic polyneuropathy. However, there is no agreement on the most sensitive parameter for an early diagnosis. One hundred patients with diabetes mellitus were examined in order to investigate the sensitivity of different electromyographic parameters. Electromyographic techniques proved to be entirely sensitive for the early diagnosis of diabetic polyneuropathy. Some of the parameters are more suitable for an early detection of peripheral nerve damage, and others, which are not so sensitive but easy to use and stable, are suitable to follow up the course of diabetic polyneuropathy.
Dissertations / Theses on the topic "Neurones sensitifs – Classification"
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Dufresne, Caroline. "Relais des informations sensorielles dans le système paralemniscal : études in vivo et in vitro chez le rat." Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/23798/23798.pdf.
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