CNS Physiology: Basal Ganglia Motor System

Vocabulary flashcards focusing on the motor functions of the Basal Ganglia (B.G.), including its circuits, muscle tone regulation, and the effects of dopamine neuron degeneration.

Thalamo-cortical activity regulation

The mechanism by which the B.G. prevents involuntary movements.

Caudate circuit

Responsible for the planning of voluntary movements and the conversion of an idea into a movement plan, including muscle names, site, order, duration, speed, and scale.

Putamen circuit

Responsible for the storage of programs of learned (familiar) motor acts, enabling rapid, automatic, and smooth movement.

Apraxia

A condition resulting from a lesion of the Putamen circuit, affecting the execution of learned movements.

Postural background

The adjustment of axial and proximal muscles through brainstem connections and ventral CST to allow for fine movements.

IRF (Inhibitory Reticular Formation)

A structure that the B.G. stimulates ($+$) to facilitate the regulation of muscle tone.

$\gamma$ motor neurons

Neurons that are inhibited ($-$) by the B.G. as part of muscle tone regulation.

$\alpha$ motor neurons

Neurons inhibited via the motor cortex by the B.G. to regulate muscle tone.

Caudate nucleus (Tone Regulation)

The part of the B.G. that acts as a stimulatory ($+++$) influence in the regulation of muscle tone.

Putamen & G.P. (Tone Regulation)

Parts of the B.G. that have inhibitory ($---$) influences in the regulation of muscle tone.

Overall effect of B.G. on muscle tone

The final outcome of B.G. activity, which is inhibitory ($-$) to muscle tone.

Generalized hypertonia

A condition that results from a lesion in the B.G. due to the loss of its inhibitory effects.

Subconscious automatic associated movements

Movements such as the swinging of arms during walking, coordinated by the B.G. and motor area 6.

Direct excitatory pathway (Dopamine loss)

Path whose activity decreases following the degeneration of dopamine-releasing neurons.

Indirect pathway (Dopamine loss)

Path whose activity increases following the degeneration of dopamine-releasing neurons.

Cerebral cortex activity (Dopamine loss)

Activity level that decreases in response to degeneration in dopamine-releasing neurons.