The Dynamics of the Weighting and Topographical Characteristics of the Excitatory Zones of the Receptive Fields of Neurons in the Cat Visual Cortex

Abstract

Acute experiments on 22 anesthetized and immobilized cats used a time slice method to study changes in the maps of 83 on and/or off receptive fields in 47 neurons in field 17 of the visual cortex. The latent period of the appearance of the receptive field averaged 88 ± 5 msec and its persistence time was 192 ± 12 msec. During generation of responses, the area and weighting on the one hand and the location of its discharge center on the other, changed in a wavelike fashion up to three times in all the neurons studied, the duration of each wave averaging 95 ± 4 msec. The discharge center of the receptive field moved in a wavelike manner in 99% of cases, moving towards and away from the center of the overall map with a period of 67.3 ± 3 msec. In 72.5% of neurons, movement of the discharge center occurred via different trajectories, which were ellipses. The functional significance of changes in the receptive fields of striate neurons in relation to the dynamics of their detector properties are discussed, as are the possible mechanisms of these rearrangements.