Workshop: Movement

Voluntary movement

controlled by higher centres of the cerebral cortex, cerebellum and basal ganglia

Idea of voluntary movement

Activation of the supplementary motor area, association areas and limbic system

Program for voluntary movement

Activation of the primary motor cortex, premotor area and supplementary motor area

Execution of voluntary movement

Activation of the pyramidal tract, extrapyramidal tract and motor neurons

Feedback for voluntary movement

Involves sensory systems, cerebellum, thalamus, basal nuclei and brainstem

Pyramidal tracts

Axons from the motor area of the cerebral cortex that form pathways for voluntary motor impulses and cross over in the medulla oblongata.

Density of muscle innervation

proportional to complexity of movement

Cerebellum

Helps coordinate movement and control posture. Dysfunction → ataxia and intention tremor

Basal ganglia

Consists of the striatum, globus pallidus and substantia nigra. Responsible for initiating, fine-tuning, and coordinating movement.

Substantia nigra

Projects inhibitory dopaminergic neurons to the striatum and receives inhibitory GABAergic neurons from the striatum.

Corpus striatum

Projects inhibitory GABAergic neurons to the substantia nigra and globus pallidus and receives inhibitory dopaminergic neurons from the substantia nigra. Contains inhibitory cholinergic interneurons.

Globus pallidus

Receives inhibitory GABAergic neurons from the striatum and projects inhibitory GABAergic neurons to the thalamus.

Thalamus

Receives inhibitory GABAergic neurons from the globus pallidus and projects excitatory glutamatergic neurons to the cortex.

Diseases of the basal ganglia

Can be hyperkinetic, dyskinetic or hypokinetic. Examples include Parkinson's and Huntington's disease.

Parkinson's disease

Lewy bodies and loss of dopaminergic neurons in the substantia nigra. Causes tremor, slow movements, and stiff/inflexible muscles.

Huntington's disease

degeneration of cholinergic and GABAergic neurons in the striatum and cerebral cortex → chorea, dementia, and eventual death

Chorea

Type of dyskinesia characterized by rapid, jerky involuntary body movements.

Tetrabenazine

May deplete monoamines and inhibit VMAT2

Antipsychotics/benzodiazepines

positive allosteric modulators of certain GABA receptors

Huntington’s treatment

tetrabenazine, antipsychotics, benzodiazepines and physical therapies