Receptive field

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

Responses to visual contours: spatio-temporal aspects of excitation in the receptive fields of simple striate neurones

Abstract: 1. The properties of the receptive fields of simple cells in the cat striate cortex have been studied by preparing average response histograms both to moving slits of light of different width and to single light-dark edges or contours. 2. The movement of a narrow (< 0·3°) slit across the receptive field gives rise to average response histograms that are either unimodal, bimodal or multimodal. A slit of light has leading (light) and trailing (dark) edges. By increasing the width of the slit it was shown that a discharge peak in the histogram coincides with the passage of one or other of the two edges over a particular region (discharge centre) in the receptive field. Each edge has its own discharge centre which is fired when the edge has the correct orientation and direction of movement. 3. The discharge centres in forty-three simple cell receptive fields were located by using one or more of the following stimuli for each cell: (i) slits of different width; (ii) single light and dark edges; (iii) a wide (3°) slit moved over a range of different velocities. The same locations were obtained when all three procedures were used on the same cell. 4. Most cells (79%) discharged to both edges though not necessarily in the same direction of movement. The majority (72%) fired in only one direction and most commonly (51%) the cells responded to both edges in this one direction. In only 16% of cells did both types of edge excite in both directions of movement. When the one type of edge, light or dark, was considered, 84% of the cells were direction selective and, for these cells, the other edge fired only in the same direction (51%), in both directions (7%), only in the opposite direction (5%) or not at all (21%). 5. Cells responding in one direction with a unimodal average response histogram may be responding to both edges, the two responses being concealed in the one discharge peak. The two discharge centres are then either nearly coincident or, more usually, slightly offset with respect to one another. Most commonly the dark edge centre is slightly in advance of the light edge centre. 6. The discharge peaks in the bimodal and multimodal types come from discharge centres that are spatially separate, each centre firing to only one type of edge. In the case of the bimodal type the light edge centre always lies ahead of the dark edge centre. 7. When a cell responds to a single edge in both directions of movement, the type of contrast effective in one direction is always the reverse of that in the other. When the cell responded in both directions, whether to one or both edges, most commonly a light edge discharge centre in one direction occupied approximately the same location in space as the dark edge centre in the reverse direction and vice versa for the other edge. 8. Temporal aspects of the discharge of simple cells have been examined by recording the responses to moving slits and single edges over a wide range of velocities.

Form and Function of the M4 Cell, an Intrinsically Photosensitive Retinal Ganglion Cell Type Contributing to Geniculocortical Vision

Abstract: The photopigment melanopsin confers photosensitivity upon a minority of retinal output neurons These intrinsically photosensitive retinal ganglion cells (ipRGCs) are more diverse than once believed, comprising five morphologically distinct types, M1 through M5 Here, in mouse retina, we provide the first in-depth characterization of M4 cells, including their structure, function, and central projections M4 cells apparently correspond to ON α cells of earlier reports, and are easily distinguished from other ipRGCs by their very large somata Their dendritic arbors are more radiate and highly branched than those of M1, M2, or M3 cells The melanopsin-based intrinsic photocurrents of M4 cells are smaller than those of M1 and M2 cells, presumably because melanopsin is more weakly expressed; we can detect it immunohistochemically only with strong amplification Like M2 cells, M4 cells exhibit robust, sustained, synaptically driven ON responses and dendritic stratification in the ON sublamina of the inner plexiform layer However, their stratification patterns are subtly different, with M4 dendrites positioned just distal to those of M2 cells and just proximal to the ON cholinergic band M4 receptive fields are large, with an ON center, antagonistic OFF surround and nonlinear spatial summation Their synaptically driven photoresponses lack direction selectivity and show higher ultraviolet sensitivity in the ventral retina than in the dorsal retina, echoing the topographic gradient in S- and M-cone opsin expression M4 cells are readily labeled by retrograde transport from the dorsal lateral geniculate nucleus and thus likely contribute to the pattern vision that persists in mice lacking functional rods and cones

Spatial summation in the receptive fields of MT neurons.

Abstract: Receptive fields (RFs) of cells in the middle temporal area (MT or V5) of monkeys will often encompass multiple objects under normal image viewing. We therefore have studied how multiple moving stimuli interact when presented within and near the RF of single MT cells. We used moving Gabor function stimuli, <1 degrees in spatial extent and approximately 100 msec in duration, presented on a grid of possible locations over the RF of the cell. Responses to these stimuli were typically robust, and their small spatial and temporal extent allowed detailed mapping of RFs and of interactions between stimuli. The responses to pairs of such stimuli were compared against the responses to the same stimuli presented singly. The responses were substantially less than the sum of the responses to the component stimuli and were well described by a power-law summation model with divisive inhibition. Such divisive inhibition is a key component of recently proposed "normalization" models of cortical physiology and is presumed to arise from lateral interconnections within a region. One open question is whether the normalization occurs only once in primary visual cortex or multiple times in different cortical areas. We addressed this question by exploring the spatial extent over which one stimulus would divide the response to another and found effective normalization from stimuli quite far removed from the RF center. This supports models under which normalization occurs both in MT and in earlier stages.