[Tegmento-thalamic interrelationships in turtles].

In immobilized, weakly anesthetized with chloralose turtles Emys orbicularis the focus of evoked potentials and the largest number of single unit responses to the stimulation of the mesencephalic tegmentum were revealed in the ventral thalamic region (a heterosensory zone with dominating somatic modality). An incomplete separation of latero- and mediotegmental projections was observed in dorsal and ventral subdivisions of the ventral thalamic region, respectively. The tegmental stimulation coinciding or preceding the electrical stimulation of the limb skin or light flash produced mainly a suppressing effect on somatic reactions of single units, the influence on visual reactions being much less significant. A possibility to compare tegmento-thalamic systems in reptiles and mammals is discussed.