Receptive field

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

Electrical responses of single cones in the retina of the turtle

Abstract: 1. Intracellular recordings have been made from single photoreceptors in the retina of the turtle. Histological sections of the retina made after injection of dye through the recording electrode reveal dye in the inner segments of single cones. 2. Following a brief flash of light the cone undergoes a hyperpolarization which is graded with the intensity of the flash. 3. The excitatory receptive field of a receptor is probably as small as the cross-section of a single cone, but accurate measurements are rendered difficult by scattering of light within the retina. 4. The voltage drop produced by a current injected into the cell is increased during the response to light. Steady hyperpolarizing currents increase the size of the response to light; depolarizing currents of increasing strength reduce and then reverse the response. 5. The results are consistent with the hypothesis that light activates the visual cell by decreasing the permeability of membrane channels which in darkness act as a shunt of the membrane.

Contrast gain control in the cat's visual system

Abstract: We have examined the idea that the adaptation of cortical neurons to local contrast levels in a visual stimulus is functionally advantageous. Specifically, cortical cells may have large differential contrast sensitivity as a result of adjustments that center a limited response range around a mean level of contrast. To evaluate this notion, we measured contrast-response functions of cells in striate cortex while systematically adapting them to different contrast levels of stimulus gratings. For the majority of cortical neurons tested, the results of this basic experiment show that contrast-response functions shift laterally along a log-contrast axis so that response functions match mean contrast levels in the stimulus. This implies a contrast-dependent change in the gain of the cell's contrast-response relationship. We define this process as contrast gain control. The degree to which this contrast adjustment occurs varies considerably from cell to cell. There are no obvious differences regarding cell type (simple vs. complex) or laminar distribution. Contrast gain control is almost certainly a cortical function, since lateral geniculate cells and fibers exhibit only minimal effects. Tests presented in the accompanying paper (37) provide additional evidence on the cortical origin of the process. In another series of experiments, the effect of contrast adaptation on physiological estimates of contrast sensitivity was evaluated. Sustained adaptation to contrast levels as low as 3% was capable of nearly doubling the thresholds of most of the cells tested. Adaptation may therefore be an important factor in determinations of the contrast sensitivity of cortical neurons. We tested the spatial extent of the mechanisms responsible for these gain-control effects by attempting to adapt cells using both a large grating and a grating patch limited to that portion of a cell's receptive field from which excitatory discharges could be elicited directly (the central discharge region). Adaptation was found to be an exclusive property of the central region. This held even in the case of hypercomplex cells, which received strong influences from surrounding regions of the visual field. Finally, we measured the time course of contrast adaptation. We found the process to be rather slow, with a mean time constant of approximately 6 s. Once again, there was considerable variability in this value from cell to cell.

Mechanisms of contour perception in monkey visual cortex. II. Contours bridging gaps

Abstract: We have studied the mechanism of contour perception by recording from neurons in the visual cortex of alert rhesus monkeys. We used stimuli in which human observers perceive anomalous contours: A moving pair of notches in 2 bright rectangles mimicked an overlaying dark bar. For control, the notches were closed by thin lines so that the anomalous contours disappeared or half of the figure was blanked, with a similar effect. Orientation-selective neurons were studied. With the receptive fields centered in the gap, 23 of 72 (32%) neurons tested in area V2 responded to the moving “bar” even though the stimulus spared their response fields, and when the notches were closed, their responses were reduced or abolished. Likewise, when half of the figure was removed, the neurons usually failed to respond. Neurons with receptive fields within 4 degrees of the fovea signaled anomalous contours bridging gaps of 1 degree-3.5 degrees. The anomalous-contour responses were compared quantitatively with response field profiles and length-summation curves and found to exceed the predictions by linear-summation and summation- to-threshold models. Summation models also fail to explain the effect of closing lines which add only negligible amounts of light. In V1, only one of 26 neurons tested showed comparable responses, and only with a narrow gap. The others responded only when the stimulus invaded the response field and did not show the effect of closing lines, or failed to respond at all. The contour responses in V2, the nonadditivity, and the effect of closure can be explained by the previously proposed model (Peterhans et al., 1986), assuming that the corners excite end-stopped fields orthogonal to the contour whose signals are pooled in the contour neurons.

The topographic organization of rhesus monkey prestriate cortex.

Abstract: 1. The topographic organization of prestriate visual cortex in the rhesus monkey has been studied both anatomically, by determining the pattern of termination of fibres passing through the corpus callosum, and physiologically, in the same animals, by plotting receptive field positions for different recording sites. Results are displayed on two-dimensional, "unfolded" maps of the cortex in the dorsal half of the occipital lobe. 2. Transcallosal fibres terminate in a narrow strip of cortex along the boundary between striate and prestriate areas and in a separate, broader, zone occupying much of the anterior bank of the lunate sulcus, the annectant gyrus, and the parietooccipital sulcus. The detailed pattern of inputs is highly complicated but shows considerable similarities from one animal to the next. 3. Physiological recordings confirmed earlier reports that regions where transcallosal fibres terminate correspond to representations of the vertical meridian in the visual field. This relationship is most precise along the striate-prestriate boundary and along the boundary of area V3 farthest from V1; it is less precise within area V4, where the pattern of transcallosal inputs is more complex. 4. A distinct, topographically organized visual area, named V3A, was found in the region between areas V3 and V4 in the lunate and parieto-occipital sulci. Area V3A differs from V2 and V3 in that both superior and inferior visual quadrants are represented in a single region of the dorsal occipital lobe. 5. The contralateral visual field is represented in a suprisingly complex fashion in areas V3A and V4. Within each area there are multiple representations of some, but perhaps not all, parts of the visual hemifield. It is unclear whether V3A and V4 should be more appropriately considered as sets of distinct sub-areas, each representing only a portion of the hemifield, or as larger areas with complicated internal topographies. 6. Most cells in areas V2, V3 and V3A are orientation selective but not selective for stimulus colour or direction of movement. In contrast, area V4 contains a higher incidence of colour selective cells and a lower incidence of orientation selectivity. These results support the notion of a functional division of labour within the prestriate cortex.

Quantitative studies of single-cell properties in monkey striate cortex. I. Spatiotemporal organization of receptive fields

Abstract: 1. The properties of single cells in striate cortex of the rhesus monkey, representing the visual field 2 degrees -5 degrees from the fovea, were examined quantitatively with stationary and moving ...