Lack of homogeneity of receptive fields of visual neurons in the cortical area 18 of the cat

Abstract

The receptive fields of "complex" neurons within area 18 of the cerebral cortex of the cat were determined by a computer-assisted method using a moving light bar substantially shorter than the long diameter of the receptive field as a visual stimulus. The visual cells repeatedly generated nerve impulses when the stimulus crossed well-defined "active points" within their receptive fields. Outside of these active points, the cells remained silent. It is suggested that the receptive fields are formed by a discontinuous accumulation of such active points. When the electrical activities of two neighbouring visual neurons are recorded simultaneously, their active points do not coincide. In addition, some active points were located outside the most prominent excitatory part of the receptive field of the studied cells. Individual visual cells typically differ in the number and distribution of active points. Since these cells best respond to a stimulus moving in a certain direction, it is suggested that they may act as direction of movement and/or velocity detectors. Alternate firing of a number of neighboring cells connected to a distributed pattern of peripheral receptors may form a system which is able to code for velocity and direction of the moving stimulus.

The Structure of Spatial Receptive Fields of Neurons in Primary Auditory Cortex of the Cat

“…Large receptive fields have long been encountered in the visual cortex (for review, see McIlwain, 1976;Maunsell and Newsome, 1987;Dinse et al, 1991). Their internal structure, like that of AI neurons, may be based on response strength and timing (Bear et al, 1971;Sasaki et al, 1971a,b;Henry, 1977;Palmer and Davis, 1981;Reinis et al, 1988), resulting in gradients that may account for many of the static and dynamic response properties exhibited by visual cortical neurons (Palmer and Davis, 1981;Albrecht and Geisler, 1991;Reid et al, 1991;Tolhurst and Dean, 1991;Jagadeesh et al, 1993). Simple cells in the primary visual cortex of the cat exhibit a latency gradient across the receptive field such that fluctuations in membrane potential evoked by moving stimuli are predicted accurately by the linear summation of the temporal response properties to stationary stimuli (Jagadeesh et al, 1993).…”

“…Simple cells in the primary visual cortex of the cat exhibit a latency gradient across the receptive field such that fluctuations in membrane potential evoked by moving stimuli are predicted accurately by the linear summation of the temporal response properties to stationary stimuli (Jagadeesh et al, 1993). Reinis et al (1988) reported that visual neurons of cat cortical area 18 fire repeatedly only when the visual stimulus is present at precisely defined locations within the receptive field, and they postulated that a population of such neurons could detect a moving image. If gradients in latency and response strength across AI receptive fields are operating similarly, then we would predict that such a neuron would exhibit sensitivity to a train of transient sounds that produce so-called "apparent sound motion" (Perrott, 1974(Perrott, , 1982.…”

Psychophysical evidence for area V2 involvement in the reduction of subjective contour tilt aftereffects by binocular rivalry

“…For any given pair of corresponding retinal locations, different neurones with different tuning characteristics will be stimulated. The strength of this response will be proportional to the strength of the input, the strength of the connection to that eye, the activity of other neurones, and perhaps any inhibitory signals from other (differently tuned) neurones (Reinis et al, 1988). In this way, each stimulus will excite a population of binocular neurones with specific tuning characteristics and this "double" population will be different from the population stimulated during normal nonrivalrous viewing because for many retinal locations, two different sets of features will coincide.…”