Purkinje cells are large neurons in the cortex of the cerebellum of vertebrate animals that play a prominent role in regulating and maintaining the proper function of motor movements. They are arranged as a single layer of cells between the molecular and granular layers of the brain. Named after the Czech histologist and physiologist Jan Evangelista Purkinje, who discovered them in 1837, the Purkinje cells are distinctive in appearance because of their large, flask-shaped cell bodies, their single long axon, and numerous threadlike branching extensions (dendrites, which receive electrochemical impulses from other cells). By releasing gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter, the Purkinje cells reduce the activity (firing rate) of other neurons, sending impulses to other places in the central nervous system. Thus, the Purkinje cells constitute the sole output of the cerebellar cortex, modulating the level and degree of motor function. See also: Brain; Central nervous system; Motor systems; Nerve; Nervous system (vertebrate); Neurobiology; Neuron

Purkinje cells (shown in red) are one of the main types of nerve cells found in the brain. These cells have elaborate branching structures called dendrites that receive signals from other nerve cells. (Photo by Yinghua Ma and Timothy Vartanian, Cornell University, Ithaca, NY; courtesy of the National Institute of General Medical Sciences, National Institutes of Health, Bethesda, MD)

Investigators have determined that the absence or dysfunction of Purkinje cells can lead to serious neurological diseases. Both genetic and environmental influences are known to damage these nerve cells. Mutant mice that serve as models for the genetic condition of Down syndrome have been seen to have reduced numbers of Purkinje cells with degenerated axons. Defective and reduced numbers of Purkinje cells have frequently been reported in individuals with autism spectrum disorders and in people with Niemann-Pick disease type C (a metabolic disease characterized by improper lipid storage). If a fetus is exposed to excessive amounts of alcohol during embryonic growth, the Purkinje cells can be destroyed, leading to fetal alcohol spectrum disorder. The rabies virus has also been linked to damaged Purkinje cells. See also: Autism; Developmental genetics; Down syndrome; Factors related to risk of autism; Fetal alcohol spectrum disorder; Metabolic disorders; Nervous system disorders; Rabies