Characteristics of on- and off-Receptive Fields in Three Groups of Cats Primary Visual Cortex Neurons With Different Balance of Excitatory and Inhibitory Influences K. A. Saltykov, N. A. Lazareva, A. S. Tikhomirov, M. A. Kulikov

To study the organization of on- and off-receptive fields (RF) of neurons in the primary visual cortex of cat two types of testing have been used. Classical mapping is tested RF neuron by small flashing light spots, but another procedure, which we call the combined mapping, it is the same test with the additional activation of the excitatory center RF by oscillating bars. Hierarchical cluster analysis and multidimensional scaling procedure showed that the studied population of neurons is not homogeneous and consists at least of three groups of neurons significantly distinguished by the excitatory-inhibitory interaction in RF. The neurons of the first group were characterized by dominance of excitatory processes in the RF. Excitatory zones of RF of these neurons had a maximal size and weight in both types of mapping being accompanied by high level consolidation (specific weight) of excitatory and inhibitory zones. In contrast the neurons of the second group were characterized by dominance of inhibition: during combined mapping the extension and weight of the inhibitory zones of RF were maximal whereas the size and weight of the excitatory ones were minimal also being accompanied by high level consolidation of excitatory and inhibitory zones. The neurons of the third group were characterized by a low-level consolidation of both the excitatory and inhibitory RF-zones in two types of mapping as well as by a comparable contribution of the excitatory and inhibitory processes to their RF that make it distinguishable from the neurons of the first and second groups. The role of feedforward excitatory and feedback inhibitory connections in the organization of receptive fields of neurons in primary visual cortex of cats is discussed.