[Evoked potentials in the optic tectum of the carp brain upon electric stimulation of the facial nerve].

The evoked potentials in the carp tectum opticum in response to stimulation of the afferent pathway for chemical nonolfactory reception, the facial nerve, are positive deflections of 5-25 ms latency which do not reverse during microelectrode submersion. According to the evoked potential amplitude and latent period 7 active zones were distingnished in the ipsilateral tectum differing from each other either in one or in both parameters. The dependence of the response evoked by facial nerve stimulation in the tectum opticum on the impulsation from the medulla is proved by the difference in latency and by disappearance of the response in the tectum while persisting in the medulla after disconnection of both areas of the brain. The existence of efferent influences from the tectum upon the primary centre is suggested as the tectum ablation causes in some parts of the medulla either complete disappearance of the facial evoked potentials or changes in their parameters.