[Reactions of dogfish shark (Squalus acanthias L.) forebrain neurons evoked by visual stimulation].

In unanesthetized immobilized spiny dogfish sharks, functional organization of the forebrain afferent projections was studied with the aid of evoked potentials (EPs) and neuronal responses to adequate stimulation of the eye with light and to electric stimulation of the optic nerve. The forebrain spontaneous unit activity (from 0.1 to 2.8 Hz) changed in response to the optic nerve electric stimulation with latency varying from 58 to 280 msec. Two foci of maximum unit activity were found at the depth of the visual area: at the levels from 850 to 1050 microns and from 1400 to 1600 microns from the forebrain surface. Histogram analysis of the data obtained showed that the main components of EPs reflected postsynaptic processes occurring in the dendrites of the forebrain visual area.