Basal Ganglia

What are the purposes of the Basal Ganglia?

• Principal component linking thalamus and cerebral cortex

• The initiation of voluntary movement

▪ The coordination of learned movement patterns (walking, lifting)

▪ The subconscious control of skeletal muscle tone

▪ Participation in cognitive functions, mood, non-motor behavior

What are the Subdivisions of the Basal Ganglia?

• Caudate

• Putamen

• Globus pallidus (with two functionally distinct parts: external and internal pallidal segment)

• Substantia nigra

• Subthalamic nucleus

What is the striatum composed of?

Composed of:

• Caudate Nucleus

• Putamen

• Ventral Striatum (Including Nucleus Accumbens)

  • (Putamen and Globus Pallidus is both in the Lentiform Nucleus)

What is the major input nucleus to the basal ganglia?

The Striatum

What forms part of the wall of the lateral ventricle?

The Caudate Nucleus

What is the Pallidum(Globus Pallidus) composed of?

Two functionally distinct subdivisions: the external (GPe) and internal(GPi) pallidal segment

The GP has a resting discharge onto the thalamus, always inhibiting it so we don’t move, until we decide to move

The external pallidal segment (GPe) regulates the indirect pathway of movement

The internal pallidal segment (GPi) represents one of the major output nuclei of the basal ganglia, sending inhibitory signals to the thalamus

Dysfunction of the globus pallidus is heavily involved in Parkinson's disease (impaired movement initiation) and Huntington's disease.

What is the only component of the Basal Ganglia that sends out excitatory signals?

The Subthalamic Nucleus (STN)

What are the two components of the Substantia Nigra?

Pars Compacta(dorsally) - contains dopaminergic neurons (affecting reward prediction, motivation, and addiction processes)

• the degradation of the pars compacta causes Parkinson’s - leading to resting tremor and difficulty initiating movements

Pars Reticularis(ventrally) - contains GABA-ergic neurons (inhibit or disinhibit brain areas)