Feedback loop between cerebellum and septal-hippocampal sites: its role in emotion and epilepsy

Data collected in animal studies suggest the existence of a feedback loop between the cerebellum, septal region, and hippocampus, the same sites where anatomic connections were demonstrated in previous studies. In monkeys, stimulation through the vermis of the cerebellum inhibits epileptiform electroencephalographic activity at these supratentorial subcortical sites. In cats, macrostimulation of one of these sites consistently affects each of the other sites, either by facilitation or inhibition of unit activity. Further, in cats, there is a consistent relation between unit activity of the Purkinje cells and seizural activity in the septal region and hippocampus induced by hippocampal stimulation. Facilitation of Purkinje cell activity by the seizural activity appears to play a role in stopping the seizure. The possibility that the feedback relation is involved in epilepsy and emotional disorders and the mechanism by which cerebellar vermal stimulation has been useful in the treatment of these disorders are considered.