Cerebellum

What is the cerebellum

The "little brain," making up 10% of total brain weight, containing around half of the brain's neurons.

Where is the cerebellum located

At the back of the brain, underlying the occipital and temporal lobes.

What are the two major parts of the cerebellum

Deep cerebellar nuclei (output structures), highly convoluted cerebellar cortex.

What are the three layers of the cerebellar cortex

Outer layer (molecular layer, axons from other layers, a few other cell types), middle layer (Purkinje cell layer, large neurons, extensive dendritic trees), inner layer (granule cell layer, small densely packed neurons).

How do granule cells receive input

From mossy fibers, excitatory projections from other brain regions.

What is the function of granule cells

Project axons to the molecular layer, split into two, run parallel, make excitatory synapses with Purkinje cell dendrites.

What is the function of Purkinje cells

Sole source of output from the cerebellum, receive excitatory input from many parallel fibers.

What are climbing fibers

Excitatory inputs from the inferior olive in the medulla, each contacts up to 10 Purkinje cells.

What are the three main functions of the cerebellum

Planning movements and motor learning, coordinating muscle activation and visually guided movements, regulating body movements for error correction and controlling balance and ocular reflexes.

What is ataxia

A disorder affecting movement coordination, balance, muscle control.

What are symptoms of ataxia

Eye movement abnormalities, muscle control issues, heart problems (in Friedrich’s ataxia).

How common is ataxia

Inherited ataxias (~3/100,000), childhood ataxias (~26/100,000), sporadic ataxias (~9/100,000).

What are the inheritance patterns of hereditary ataxias

Autosomal dominant, autosomal recessive, X-linked.

What are causes of acquired ataxia

Vitamin deficiencies, autoimmune disorders, infections, toxic substance exposure (e.g., alcohol), various cancers.

What happens in ataxia at the cellular level

Loss of neurons in the granule layer, Purkinje cell arborization loss.

What are the treatments for ataxia

Physiotherapy, occupational therapy, language therapy, medications for symptoms (depression, dizziness, imbalance, muscle spasm, tremor, etc.).

What are future research directions for ataxia

Better understanding of causes, more research into rare diseases, stem cell therapies.

What is the current status of stem cell therapy for ataxia

Mostly studied in animal models, some success in umbilical cord stem cell trials in rats and mice, human trials are limited.