Receptive field

About: Receptive field is a research topic. Over the lifetime, 8537 publications have been published within this topic receiving 596428 citations.

Abnormalities of spatial and temporal sensory discrimination in writer's cramp.

Abstract: Clinical observations of patients with writer's cramp suggest that abnormalities of the sensory system may be a frequent finding in this disorder. Neurophysiological data from an animal model of focal dystonia have revealed cells in somatosensory cortex with enlarged and overlapping tactile receptive fields. However, psychophysical studies so far have been unable to document a clinical correlate supporting a similar enlargement of receptive fields in humans. We compared the fingertip discrimination of the orientation of fine spatial gratings between writer's cramp and control subjects and found a significant decrease in grating sensitivity in the patients, consistent with the possibility of enlarged tactile receptive fields. In addition, we duplicated previous experiments showing an abnormality of tactile temporal discrimination. The results provide psychophysical measures which may relate to the development of sensory cortical reorganization in patients with writer's cramp.

The structure and symmetry of simple-cell receptive-field profiles in the cat's visual cortex

Abstract: Receptive fields of simple cells in the cat visual cortex have recently been discussed in relation to the 'theory of communication' proposed by Gabor (1946). A number of investigators have suggested that the line-weighting functions, as measured orthogonal to the preferred orientation, may be best described as the product of a Gaussian envelope and a sinusoid (i.e. a Gabor function). Following Gabor's theory of 'basis' functions, it has also been suggested that simple cells can be categorized into even- and odd-symmetric categories. Based on the receptive field profiles of 46 simple cells recorded from cat visual cortex, our analysis provides a quantitative description of both the receptive-field envelope and the receptive-field 'symmetry' of each of the 46 cells. The results support the notion that, to a first approximation, Gabor functions with three free parameters (envelope width, carrier frequency and carrier phase) provide a good description of the receptive-field profiles. However, our analysis does not support the notion that simple cells generally fit into even- and odd-symmetric categories.

Two-Photon Imaging of Nonlinear Glutamate Release Dynamics at Bipolar Cell Synapses in the Mouse Retina

Abstract: Alpha/Y-type retinal ganglion cells encode visual information with a receptive field composed of nonlinear subunits. This nonlinear subunit structure enhances sensitivity to patterns composed of high spatial frequencies. The Y-cell's subunits are the presynaptic bipolar cells, but the mechanism for the nonlinearity remains incompletely understood. We investigated the synaptic basis of the subunit nonlinearity by combining whole-cell recording of mouse Y-type ganglion cells with two-photon fluorescence imaging of a glutamate sensor (iGluSnFR) expressed on their dendrites and throughout the inner plexiform layer. A control experiment designed to assess iGluSnFR's dynamic range showed that fluorescence responses from Y-cell dendrites increased proportionally with simultaneously recorded excitatory current. Spatial resolution was sufficient to readily resolve independent release at intermingled ON and OFF bipolar terminals. iGluSnFR responses at Y-cell dendrites showed strong surround inhibition, reflecting receptive field properties of presynaptic release sites. Responses to spatial patterns located the origin of the Y-cell nonlinearity to the bipolar cell output, after the stage of spatial integration. The underlying mechanism differed between OFF and ON pathways: OFF synapses showed transient release and strong rectification, whereas ON synapses showed relatively sustained release and weak rectification. At ON synapses, the combination of fast release onset with slower release offset explained the nonlinear response of the postsynaptic ganglion cell. Imaging throughout the inner plexiform layer, we found transient, rectified release at the central-most levels, with increasingly sustained release near the borders. By visualizing glutamate release in real time, iGluSnFR provides a powerful tool for characterizing glutamate synapses in intact neural circuits.

Fine structure of myelinated mechanical nociceptor endings in cat hairy skin

Abstract: High-threshold mechanoreceptors (mechanical nociceptors) with myelinated axons were electrophysiologically identified in hairy skin of the cat as described by Burgess and Perl ('67). Such elements possess receptive fields consisting of a number of punctate areas from which maximal firing can be elicited by intense (skin-damaging) mechanical stimuli. The spots of the receptive field are separated from each other by unresponsive regions, i.e., by skin areas from which responses cannot be evoked by stimuli effective at the spots. Fine steel pins were inserted to bracket closely a number of the spotlike responsive areas for each of several units. After aldehyde perfusion of the animal, osmification of the tissue and embedding in plastic, the marked skin zones were examined in semithin and ultrathin sections at the light and electron microscopic level. Near each delineated area, a thinly myelnated axon was fond that could be traced to the papillary layer where it loses its myelin sheath. Unmyelinated axons accompanied by thin Schwann cell processes were then traced and found to penetrate the epidermal basal lamina in one of the papillae. At the epidermal penetration site, the axons contained both clear round, and large, dense core vesicles; at this level, the surrounding Schwann cell cytoplasm exhibited numerous pinocytotic vesicles. The zone of pentration may constitute the receptive apparatus. Some of these axons have been traced within the basal epidermal layer where they become surrounded by keratinocytes, lose their Schwann sheath, and apparently terminate. This overall morphological pattern was consistently present in the demarked areas of focal responsiveness, and was rare in the surrounding skin; this and its difference from other cutaneous neural endings suggest that the intraepidermal axon-Schwann cell complex constitutes the receptive structure for myelinated mechanical nociceptors. It is suggested that such complexes are the sense organs responsible for initiating the sensation of pricking pain produced by localized mechanical injury of the skin.