Binding of signals relevant for action: towards a hypothesis of the functional role of the pontine nuclei

If numbers matter, the projection that connects the cerebral cortex to the cerebellum is probably one of the most-important pathways through the CNS. Its extensive development as one ascends the phylogenetic scale parallels t hat of the cerebral hemispheres and the cerebellum, and it accompanies impr ovements in motor skills, suggesting that this system might have a decisive role in the generation of skilled movement. This article focuses on the po ntine nuclei (PN), which are intercalated in the cerebro-cerebellar pathway , a large nuclear complex in the ventral brainstem of mammals,whose raison d'etre has as yet not been examined. By considering recent morphological an d electrophysiological findings, this article argues that the PN are an int erface that is needed to accommodate the grossly different computational pr inciples governing the cerebral cortex and the cerebellum.