[Conduction of excitation in the cat vixual system]

The responses of striate cortex units to the lateral geniculate body and optic tract stimulations were recorded extra- and intracellularly in experiments on cats immobilized with d-tubocurarine. 92% of responded cells were activated orthodromically with a latency ranging between 2 and 12.5 ms. Most of these responses may be divided into three groups--2-2.5, 3-3.5, 4-4.5 ms. The latency of each group coincided with the latency of three different parts of the evoked potentials positive components. 8% of the responding cells were activated antidromically. The difference of the response latency to the stimulation of both structures in 55.8% of cells ranged from 0.5 to 1 ms. The existence of three main groups of optic radiation fibres with conduction velocities of 28.5-16.6, 11.7-8.9, 7.4-6 m/s is postulated. A conclusion is made that peculiarities of the afferent volley formed in retino-geniculate paths are not significantly changed after its processing in the lateral geniculate body.