[Temporal signal summcation by at visual cortex neurons].

The summation temporal of signals in neurons of field 17 of the visual cortex was studied in immobilized and unanaesthetized cats. The unit responses to optimal local light stimuli were recorded under conditions of light adaptation. Critical duration of the summation temporal in different units was 5-100 ms, with mean value equal to 31.45 +/- 5.67 ms. Neurons in the central part of the field differed from the peripheral ones by a shorter critical summation temporal, a lower background discharge frequency and a smaller duration of the first burst in the response. In neurons with simple receptive fields the summation temporal was considerably shorter than in complex neurons. The obtained results are compared with data from literature on neurons of cat retina and lateral geniculate nucleus and discussed with respect to division of ascending afferent visual projections into X and Y (1a and 1b) groups.