Lateral segment of globus pallidus

The lateral segment of globus pallidus, also called the globus pallidus externus (GPe), is the larger, lateral subdivision of the globus pallidus. It lies medial to the putamen and lateral to the medial medullary lamina, which separates it from the globus pallidus internus (GPi).

Role of GPe in indirect neural circuity

The GPe receives predominantly inhibitory GABAergic input from the striatum and has important connections with the subthalamic nucleus. It functions mainly as an intrinsic or relay nucleus of the basal ganglia, particularly within the indirect pathway.

In the indirect pathway, inhibition of the lateral segment of globus pallidus (GPe) by the striatum reduces its inhibitory influence on the subthalamic nucleus. The resulting increase in subthalamic activity excites the GPi and substantia nigra pars reticulata, increasing inhibition of the thalamus and thereby helping to suppress excessive or unwanted movement.

Clinical correlate

Abnormal activity within circuits involving the globus pallidus contributes to movement disorders, particularly Parkinson disease.