Which nucleus in the basal ganglia circuit is the primary inhibitory output station that projects to the thalamus, and what neurotransmitter does it use?
- A Globus pallidus externus (GPe); GABA
- B Subthalamic nucleus (STN); glutamate
- C Caudate nucleus; dopamine
- D Globus pallidus internus (GPi) and substantia nigra pars reticulata (SNr); GABA ✓
Explanation
The globus pallidus internus (GPi) and substantia nigra pars reticulata (SNr) are the main output nuclei of the basal ganglia. Both use GABA to tonically inhibit thalamocortical neurons. In the indirect pathway, the STN excites GPi/SNr using glutamate, increasing inhibition of the thalamus (suppressing movement). In Parkinson's disease, loss of dopamine from the substantia nigra pars compacta disinhibits the indirect pathway, increasing GPi/SNr output and thus excessive thalamic inhibition — explaining bradykinesia. GPe uses GABA to inhibit STN as part of the indirect pathway but is not an output to thalamus.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.