purkinje neurons

Purkinje cell
Professor M Häusser, Sarah Rieubland and Arnd Roth, UCL
Winner of the Wellcome Image Awards, 2015.
“Scanning electron micrograph of tree-like branches (dendritic tree) spreading out from a particular type of nerve cell (Purkinje cell, or neurone) found in the brain. The finger-like projections in this elaborate network act like tiny sensors, picking up information and passing on messages to help control and coordinate muscle movement. This particular neurone is from the cerebellar cortex in a rat brain.” 

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MNEMONIC: Diseases showing anticipation associated with Triplet Repeat Expansion

Anticipation: pattern of inheritance, symptoms of a genetic disorder become apparent at an earlier age as it is passed on to the next generation, an increase of severity of symptoms is also noted

Huntington Disease (HD)

  • Mnemonic: “HD es una CAGada” in Spanish, cagada means something bad, shitty, to be more precise. This is to remember the CAG trinucleotid repeat.
  • Autosomal Dominant, chromosome 4: “Huntin’ 4 food”
  • Chorea: purposeless movement of limbs, due to a loss of GABAergic neurons of neostriatum (caudate nucleus and putamen) of indirect pathway.
  • Personality changes, dementia, tendency for suicide

External image

Fragile X Syndrome

  • CGG trinucleotid repeat
  • X dominant, FMR 1
  • Mental retardation, large ears and jaw. post-pubertal macro-orchidism (males), attention deficit disorder (females)

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Friedreich Ataxia

  • GAA trinucleotid repeat
  • Autosomal recessive, Frataxin gene, chromosome 9
  • Neuronal degeneration: dorsal root ganglia, Clarke column (spinocerebellar tract), posterior column of spinal cord, dentate nucleus, Purkinje cells, Betz neurons, CN nuclei of VII, X, XII
  • Progressive gait & limb ataxia, arreflexia, hypertrophic cardiomyopathy, axonal sensory neuropathy, kyphoscoliosis, dysarthria, hand clumsiness, loss of sense of position, impaired vibratory sensation.

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MyoTonic DysTrophy

  • CTG trinucleotid repeat
  • Autosomal Dominant, MD1: chromosome 3; MD2: chromosome 19
  • Muscle loss, cardiac arrythmia, testicular atrophy, frontal baldness, cataracts.

External image

Purkinje neurons play an essential role in motor function. Here the Purkinje neurons reach their arbor-like dendrites into the molecular layer of the developing cerebellum of a mouse. The mostly green cells at the bottom left (expand image to full view) are cerebellar granule cells, which relay information from the nervous system to the Purkinje neurons.