Double Receptive Fields of Neurons of the Lateral Geniculate Body of the Cat

We studied spatial organization of the receptive fields (RF) of neurons of the lateral geniculate body (LGB) on unanesthetized cats (pretrigeminal brainstem section). After identification of localization and borders of the RF of the neuron under study, we scanned with a sufficient resolution the entire visual field and tried to find additional space zones, whose stimulation could influence the impulse activity of the neuron. These experiments demonstrated that 24 neurons of 167 examined units (14%) could react to the presentation of visual stimuli within the visual space outside the main RF, but we were unable to determine borders of these additional zones with a sufficient accuracy. In 12 neurons (7% of the group under study), localization, dimensions, and specific features of an additional RF (RF-2) could be clearly determined. As a rule, the center of the RF-2 was localized at a distance of 20-40^O; or even farther from the center of the main RF (RF-1). To activate the neuron from the RF-2, application of greater visual stimuli was necessary (as compared with stimulation of the RF-1). Thus, two RF of one and the same neuron had dissimilar spatial organizations and qualitatively differed from each other in their stationary and dynamic characteristics. Considering our findings, we hypothesize that the RF-2 of LGB neurons can play a certain role in perception of large objects within the visual field of the animal by promoting formation of the avoidance reaction.