SPATIOTEMPORAL ASPECTS OF NEURON RESPONSES TO MOVING VISUAL STIMULI IN EXTRASTRIATE AREA 21A OF THE CAT CORTEX.

The properties of visually driven neurons in both primary visual cortex and extrastriate cortical areas are as a rule mostly determined by spatial and time-related constraints of the neuronal receptive fields (RF). In our experiments we tried to investigate in detail the relationship between the RF spatial and temporal parameters, during neuron activation by a visual stimulus. Extracellular recording of single-cell activity combined with visual field masking method was used. We find that in some cases the RF temporal parameters of the responses were not correlated with the spatial ones. Moreover, it was revealed that some regions in the RF, mainly the central region, when excited by visual stimulus presented in isolation through an aperture, while the rest of the RF and the whole visual field is masked, may elicit a response with spatial and temporal parameters comparable to that evoked by the same stimulus in the absence of masking. A suggestion is put forward on possible feedback influences in central processing of visual information in extrastriate cortical areas. [ABSTRACT FROM AUTHOR]