Contrast-Dependent Restructuring of Neuronal Visual Receptive Fields in the Cat Extrastriate Cortex

Spatial modifications of neuronal visual receptive fields (RFs) in the cat extrastriate cortex were studied. The response properties and spatial organization of the RFs of area 21a neurons were investigated using visual stimuli of two opposite contrasts, with particular attention to the stationary structure of these RFs. It was found that the infrastructure of the RF of a visually sensitive neuron undergoes certain restructuring related to the contrast of the visual stimuli used. In most cases, discharge centers of the RF subfields changed their response profile and spatial localization within the RF depending on the stimulus contrast. Stationary RFs defined by presentation of flashing spots of two opposite contrasts (bright and dark) differed from each other quantitatively and qualitatively, indicating the influence of background illumination on the pattern of neuronal responses. It is hypothesized that the RF surrounding significantly influences central processing of incoming visual information and image recognition in the extrastriate cortex.

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