page_title: Internal globus pallidus
section_title: Function
hierarchical_section_title: Internal globus pallidus / Function
caption_attribution_description: English: Classic connectivity diagram of the Basal Ganglia, showing glutamatergic pathways as red, dopaminergic as magenta and GABA pathways as blue.
context_page_description: The internal globus pallidus and the external globus pallidus make up the globus pallidus. The GPi is one of the output nuclei of the basal ganglia. The GABAergic neurons send their axons to the ventral anterior nucleus and the ventral lateral nucleus in the dorsal thalamus, to the centromedian complex, and to the pedunculopontine complex.
  The efferent bundle is constituted first of the ansa and lenticular fasciculus, then crosses the internal capsule as the Edinger's comb system then arrives at the laterosuperior corner of the subthalamic nucleus and constitutes the field H₂ of Forel, then H, and suddenly changes its direction to form field H₁ that goes to the inferior part of the thalamus. The distribution of axonal islands is widespread in the lateral region of the thalamus. The innervation of the central region is done by collaterals.
  The internal globus pallidus contains GABAergic neurons, which allow for its inhibitory function. As the GPi, along with the substantia nigra pars reticulata, forms the output of the basal ganglia, these neurons extend to the thalamus, the centromedian complex and the pedunculopontine complex.
context_section_description: The GPi acts to tonically inhibit the ventral lateral nucleus and ventral anterior nucleus of the thalamus. As these two nuclei are needed for movement planning, this inhibition restricts movement initiation and prevents unwanted movements.
caption: Direct and indirect striatopallidal pathways: Glutamatergic pathways are red, dopaminergic are magenta and GABAergic pathways are blue. STN: Subthalamic Nucleus SNr: Substantia Nigra pars reticulata SNc: Substantia Nigra pars compacta GPe: External globus pallidus
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