Receptive field

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

Spatial mapping in the primate sensory projection: Analytic structure and relevance to perception

Abstract: The retinotopic mapping of the visual field to the surface of the striate cortex is characterized as a longarithmic conformal mapping. This summarizes in a concise way the observed curve of cortical magnification, the linear scaling of receptive field size with eccentricity, and the mapping of global visual field landmarks. It is shown that if this global structure is reiterated at the local level, then the sequence regularity of the simple cells of area 17 may be accounted for as well. Recently published data on the secondary visual area, the medial visual area, and the inferior pulvinar of the owl monkey suggests that same global logarithmic structure holds for these areas as well. The available data on the structure of the somatotopic mapping (areaS-1) supports a similar analysis. The possible relevance of the analytical form of the cortical receptotopic maps to perception is examined and a brief discussion of the developmental implications of these findings is presented.

Visual cortical mechanisms detecting focal orientation discontinuities

Abstract: NEURONS in the primary visual cortex (VI) respond in well defined ways to stimuli within their classical receptive field, but these responses can be modified by stimuli overlying the surrounding area1–7 For example patch-suppressed cells respond to gratings of a specific orientation within their classical receptive field, but the response diminishes if the grating is expanded to cover the surrounding area1–7 We report here more complex effects in many such cells When stimulated at their optimal orientation, introducing a surrounding field at a significantly different (for example, orthogonal) orientation enhanced their output by both a disinhibi-tory mechanism and an active facilitatory mechanism producing'supra-optimal' responses Importantly, some cells responded well if the orientations of centre and surround stimuli were swapped The output reflected the discontinuity because neither stimulus component alone was effective Under these stimulus conditions simultaneously recorded cells with orthogonally oriented receptive fields showed correlated firing consistent with neuronal binding to the configuration We propose a mechanism integrating orientation-dependent information over adjacent areas of visual space to represent focal orientation discontinuities such as junctions or corners

Contrast's effect on spatial summation by macaque V1 neurons.

Abstract: Stimulation outside the receptive field of a primary visual cortical (V1) neuron reveals intracortical neural interactions. However, previous investigators implicitly or explicitly considered the extent of cortical spatial summation and, therefore, the size of the classical receptive field to be fixed and independent of stimulus characteristics or of surrounding context. On the contrary, we found that the extent of spatial summation in macaque V1 neurons depended on contrast, and was on average 2.3-fold greater at low contrast. This adaptive increase in spatial summation at low contrast was seen in cells throughout V1 and was independent of surround inhibition.

Cortical point-spread function and long-range lateral interactions revealed by real-time optical imaging of macaque monkey primary visual cortex

Abstract: Processing of retinal images is carried out in the myriad dendritic arborizations of cortical neurons. Such processing involves complex dendritic integration of numerous inputs, and the subsequent output is transmitted to multiple targets by extensive axonal arbors. Thus far, details of this intricate processing remained unexaminable. This report describes the usefulness of real-time optical imaging in the study of population activity and the exploration of cortical dendritic processing. In contrast to single-unit recordings, optical signals primarily measure the changes in transmembrane potential of a population of neuronal elements, including the often elusive subthreshold synaptic potentials that impinge on the extensive arborization of cortical cells. By using small visual stimuli with sharp borders and real-time imaging of cortical responses, we found that shortly after its onset, cortical activity spreads from its retinotopic site of initiation, covering an area at least 10 times larger, in upper cortical layers. The activity spreads at velocities from 100 to 250 microns/msec. Near the V1/V2 border the direct activation is anisotropic and we detected also anisotropic spread; the “space constant” for the spread was approximately 2.7 mm parallel to the border and approximately 1.5 mm along the perpendicular axis. In addition, we found cortical interactions between cortical activities evoked by a small “center stimulus” and by large “surround stimuli” positioned outside the classical receptive field. All of the surround stimuli used suppressed the cortical response to the center stimulus. Under some stimulus conditions iso-orientation suppression was more pronounced than orthogonal-orientation suppression. The orientation dependence of the suppression and its dependency on the size of some specific stimuli indicate that at least part of the center surround inhibitory interaction was of cortical origin. This findings reported here raise the possibility that distributed processing over a very large cortical area plays a major role in the processing of visual information by the primary visual cortex of the primate.