Synaptic Organization of Cerebellar Purkinje Cell

Abstract

Synaptic organization contributes important role in exerting output of neuron. Here we present the 3-D reconstructed image of the synaptic organization in cerebellar Purkinje cell (PC) from transmission electron microscopic analysis. The serial ultrathin sections in the horizontal plane were prepared from the basal pole of cell soma to the distal end of PC dendrites. Purkinje cell dendrite is categorized into three domains according to synapse input: the proximal domain innervated by climbing fibers (CF), but not by parallel fibers fibers (PF), the intermediate domain with mixed CF/PF innervation, and the distal domain innervated by PF, but not by CF. In addition, single climbing fiber stem, which climb up along Purkinje cell dendrite from soma-dendrite border, divides into many branches with associating dendritic branches. Thus, single climbing fiber stem exclusively innervates single Purkinje cell. Recently, the molecules; Glutamate receptor δ2 subunit, Cbln1, and P/Q type Ca²⁺ channel α1A subunit, are reported to perform formation and maintenance of the characteristic synaptic organization, as well as the existence of parallel fibers and the electrical activity of climbing fiber.