Basal ganglia

What is the basal ganglia? 

The basal ganglia is a group of sub-cortical nuclei thought to be involved in motor control and learning. The nuclei comprising the basal ganglia include the caudate, putamen, globus pallidus, the subthalamic nucleus, and the substantia nigra. The caudate and putamen together form the striatum, while the globus pallidus and the putamen together form the lenticular nucleus. The striatum is the principal input centre, receiving afferents primarily from the cortex, but also from the substantia nigra, thalamus, and external globus pallidus. There are two primary pathways from the striatum through the basal ganglia (‘direct’ and ‘indirect’), which incorporate different components of the basal ganglia circuitry, and play different roles in controlling and planning movements and cognition.

What is the evidence for basal ganglia alterations?

High quality evidence suggests increased grey matter in the caudate, bilateral putamen, and globus pallidus of people with schizophrenia compared to people without schizophrenia (‘controls’). Lower quality evidence suggests similar findings in childhood-onset schizophrenia. Moderate quality evidence suggests reduced bilateral caudate nucleus grey matter in people with first-episode psychosis, particularly people who have never been medicated, compared to people with schizophrenia, people at high risk of psychosis, and compared to controls. High quality evidence suggests a small effect of greater reductions over time in the left caudate in people with schizophrenia compared to controls.

Moderate quality evidence suggests people with schizophrenia show reduced activity in the bilateral claustrum and the right putamen during executive functioning tasks. Moderate to low quality evidence suggests no functional abnormality in the basal ganglia during cognitive control, long-term and working memory, and language processing tasks. Moderate to low quality evidence also suggests no differences in D2/D3 receptor availability in the substantia nigra of unmedicated people with schizophrenia compared to controls.

March 2019

Last updated at: 3:44 am, 28th March 2019
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