Cellule de Purkinje

Purkinje cells, or Purkinje neurons, are a class of GABAergic inhibitory neurons located in the cerebellum. They are named after their discoverer, Czech anatomist Jan Evangelista Purkyně, who characterized the cells in 1839. These cells are some of the largest neurons in the human brain (Betz cells being the largest), with an intricately elaborate dendritic arbor, characterized by a large number of dendritic spines. Purkinje cells are found within the Purkinje layer in the cerebellum. Purkinje cells are aligned like dominos stacked one in front of the other. Their large dendritic arbors form nearly two-dimensional layers through which parallel fibers from the deeper-layers pass. These parallel fibers make relatively weaker excitatory (glutamatergic) synapses to spines in the Purkinje cell dendrite, whereas climbing fibers originating from the inferior olivary nucleus in the medulla provide very powerful excitatory input to the proximal dendrites and cell soma. Parallel fibers pass orthogonally through the Purkinje neuron's dendritic arbor, with up to 200,000 parallel fibers forming a Granule-cell-Purkinje-cell synapse with a single Purkinje cell. Each Purkinje cell receives approximately 500 climbing fiber synapses, all originating from a single climbing fiber. Both basket and stellate cells (found in the cerebellar molecular layer) provide inhibitory (GABAergic) input to the Purkinje cell, with basket cells synapsing on the Purkinje cell axon initial segment and stellate cells onto the dendrites. Purkinje cells send inhibitory projections to the deep cerebellar nuclei, and constitute the sole output of all motor coordination in the cerebellar cortex. The Purkinje layer of the cerebellum, which contains the cell bodies of the Purkinje cells and Bergmann glia, express a large number of unique genes. Purkinje-specific gene markers were also proposed by comparing the transcriptome of Purkinje-deficient mice with that of wild-type mice.