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 that of the cerebral hemispheres and the cerebellum, and it accompanies improvements in motor skills, suggesting that this system might have a decisive role in the generation of skilled movement. This article focuses on the pontine 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 and electrophysiological findings, this article argues that the PN are an interface that is needed to accommodate the grossly different computational principles governing the cerebral cortex and the cerebellum.