Synaptogenesis and synapse elimination in developing cerebellum

Abstract

Purkinje cells (PCs) are the sole output neurons of the cerebellar cortex and play pivotal roles in coordination, control, and learning of movements. In the adult cerebellum, they receive two distinctive excitatory synaptic inputs from parallel fi bers (PFs), the axons of granule cells (GCs), and climbing fi bers (CFs) arising from the inferior olivary nucleus in the medulla oblongata. Each PC receives functionally weak but numerous (c.a. 100,000 in mice) PF synapses, on spines of distal dendrites. In contrast, most PCs are innervated by single but functionally very strong CFs on stubby spines of their proximal dendrites. PCs receive GABAergic inhibitory synaptic inputs from basket and stellate cells (BCs and SCs) in the molecular layer. These synaptic organizations are established mostly during the fi rst 3 weeks of rodent’s life. In this article, we briefl y review how these microcircuits around PCs are organized, maintained and modifi ed during postnatal development.