SPATIAL SUMMATION PROCESSES IN THE RECEPTIVE FIELDS OF VISUALLY DRIVEN NEURONS OF THE CAT'S CORTICAL AREA 21A

摘要

The area 21 as a visually sensitive area of the cat's extrastriate cortex was first defined by Heath a. Jones (15) on the basis of its morphology and cytoarchitectonics. Detailed investigations of the retinotopic organization and morphology of interconnections of area 21 a with other brain structures have shown that area 21 consists of two distinct areas 21a and 21b (23, 30, 32, 33). More recent evidence has indicated, that the great majority of area 21a visuallydriven neurons are orientationsensitive (20, 31, 36, 38, 39). Furthermore, increasing evidence suggests that in addition to orientation selectivity, the neurons of area 21a are involved in the central processing of infonTnation concerning the shape perception of objects (8, 38). Earlier Xing a. Gerstain (40, 41, 42) on the basis of modeling experiments, concluded that the central processing of sensory information was carried out by clusters of neurons that were organized in functional groups. The authors had emphasized that such groups were dynamic and could be changed by input stimuli. The latest findings presented by Warren et al. (37) have confirmed this interpretation. From this point of view, the fine spatial properties of area 21 a neurons, become important as a basic neurophysiological substrate in the central processing of integration and differentiation of the visual information received by the neuron. Despite the great interest of researchers on the functional significance of cortical area 21 a in the central processing of visual information, it has not been investigated in sufficient depth until now. Our earlier investigations concerning lateral geniculate neurons RF organization (13) have revealed well defined influence on the neuron activity from the sdrrounding visual field outside of the RF. Later, investigating RF organization of visually driven neurons in extrastriate area 21b Khachvankian et al.