[Effect of stimulation of the preoptic region of the hypothalamus on the activity of individual optic tract fibers in rabbits].

Statistical background characteristics and impulse activity of some fibres of the optical tract evoked by light flashes were compared before and after stimulation of the preoptic hypothalamic region in listenin-immobilized rabbits. It was shown that the influence of the high frequency preoptical hypothalamus stimulation correlates with the pattern of responses to light flashes observed when recording from the optical tract fibres. In most cases the preoptical hypothalamus stimulation caused an increase of the background activity and facilitation of responses to light flashes. Phasic response to a light flash with short latency (42 ms), consisting of a long train of pulses and tonic responses with long latency (155 ms) were facilitated to a greater extent. The facilitation of short-latent (35 ms) phasic responses to a light flash consisting of a short train of phases after the preoptical hypothalamus stimulation was not clearly pronounced or was inhibited.