Purkinje cells are a type of neuron found in the cerebellar cortex, at the base of the brain. They are among the largest neurons, and are responsible for most of the electrochemical signaling in the cerebellum. These cells take their name from Czech anatomist Jan Evangelista Purkyne, who discovered them in 1837.
Purkinje neurons are characterized by an elaborate branching structure of dendrites, the projections that receive electrochemical impulses from other cells. They are densely stacked within the cerebellar cortex, where they are intersected by numerous parallel fibers arising from the granule cells of the cerebellar cortex. Purkinje neurons are classified as inhibitory, as they release the neurotransmitter GABA, which binds to receptors that work by inhibiting, or reducing, the firing rate of neurons. They send inhibitory projections into dense neuron clusters in the center of the cerebellum called the deep cerebellar nuclei.
The Purkinje cells and the cerebellum are essential to the body’s motor function. Disorders involving the Purkinje cells usually negatively affect the patient’s movement. The Purkinje cells may be affected by both genetic and acquired disorders.
Genetic disorders affecting the Purkinje cells include cerebellar hypoplasia, autism, ataxia telangiectasia, and Niemann Pick disease Type C. In cerebellar hypoplasia, the patient is born with an underdeveloped cerebellum, either because the Purkinje cells never fully developed or because they degenerated in utero. In other genetic disorders affecting the cerebellum, symptoms may not appear until a few years after birth, after which they can worsen. Niemann Pick disease Type C sometimes causes death within a few months after birth, and in other cases does not manifest until adolescence. All cerebellar disorders are characterized by reduced motor function, such as an abnormal way of walking, seizures, involuntary eye movement, or uncoordinated movement of the limbs.
The Purkinje neurons can also be damaged by disorders developed later in life, such as autoimmune disorders including acquired immuno-deficiency syndrome (AIDS) and neurodegenerative disorders that are not genetic in nature. They are also subject to damage from toxic elements in the environment. Excessive use of alcohol or lithium can cause the cerebellum to degenerate. Stroke can also damage the Purkinje neurons.
There is no cure for any disorders affecting the Purkinje neurons. Any treatment is therefore supportive and symptomatic. For children born with cerebellar disorders, speech therapy, occupational therapy, and physical therapy can be helpful in improving the child’s motor skills.