Receptive Fields of Visually Sensitive Neurons of the Extrastriate Associative Area 21b of the Cat Cerebral Cortex

• Published in: Neurophysiology (New York) Vol. 37; no. 3; pp. 194 - 204
• Main Authors: Khachvankyan, D. K., Harutiunian-Kozak, B. A., Martirosyan, L. V., Ekimyan, A. A., Grigoryan, G. G., Kozak, J. A., Bagdasaryan, E. G.
• Format: Journal Article
• Language: English
• Published: New York Springer Nature B.V 01.05.2005
• ISSN: 0090-2977; 1573-9007
• DOI: 10.1007/s11062-005-0065-8

Organization of the receptive fields (RFs) of neurons of the extrastriate associative region 21b of the cerebral cortex was studied in cats. Most neurons under study (63%) were "monocular," while 37% of the cells were "binocular" units. Among 178 neurons examined in detail, heterogeneous RF functional organization was typical of about 76% of the units; point-to-point testing of the entire RF area by stationary stimuli resulted in the generation of various types of responses (on, off, or on-off). The rest of the neurons (24%) generated homogeneous responses. The dimension, form, and functional organization of RFs of the neurons under study depended to a certain extent on the parameters of visual stimuli used for the measurements. Examination of the influence of the visual space, which surrounded the RF, on responses of the neurons evoked by stimulation of the RF per se showed that darkening of the visual space adjacent to the RF inhibited neuronal responses to moving stimuli; in some cases the responses were totally suppressed. Analysis of spatial overlapping of the RF sequentially recorded in the course of each insertion of the electrode showed that the density of distribution of the overlapping RF areas of neighboring neurons with the RF of the examined neuron is irregular, and that the RF is of a mosaic nature. We hypothesize that the visual space surrounding the RF plays a significant role in the formation of responses of visually sensitive neurons to presentation of moving stimuli.