External globus pallidus

External globus pallidus
External globus pallidus (GPe) seen in 2nd image from the left
Details
Identifiers
Latin	Globus pallidus externus, globus pallidus lateralis
NeuroNames	hier-214
NeuroLex ID	Globus pallidus external segment
TA	A14.1.09.509
FMA	61839
Anatomical terms of neuroanatomy []

The external globus pallidus (GPe) (or lateral globus pallidus) combines with the internal globus pallidus to form the globus pallidus, an anatomical subset of the basal ganglia. Globus pallidus means "pale globe" in Latin, indicating its appearance. The external globus pallidus is the segment of the globus pallidus that is relatively further (lateral) from the midline of the brain.

The GPe GABAergic neurons, allow for its inhibitory function and projects axons to the subthalamic nucleus (in the diencephalon), the striatum, internal globus pallidus (GPi) and substantia nigra pars reticulata.

The GPe is particular in comparison to the other elements of the set by the fact that it does not work as an output base of the basal ganglia (not sending axons to the thalamus) but as the main regulator of the basal ganglia system. It is sometimes used as a target for deep brain stimulation as a treatment for Parkinson's disease.

The basal ganglia functions to tonically inhibit movement, mainly in the absence of motor cortex command, via GABAergic inhibition of the ventral lateral nucleus and ventral anterior nucleus of the thalamus, as well as the superior colliculus and mesopontine tegmentum of the brain stem. When movement is required, the cerebral cortex sends commands to the striatum, which directly inhibits the medial globus pallidus and substantia nigra pars reticulata, decreasing thalamus and brainstem inhibition. As the pathway from the striatum to the medial globus pallidus is monosynaptic (containing one synapse), it is called the Direct Striatopallidal Pathway.