Indirect pathway

Indirect Pathway is a component of the Basal Ganglia circuitry in the human brain. It is involved in the regulation of voluntary movements and plays a crucial role in motor control. The indirect pathway is also known as the indirect pathway of movement or the indirect motor pathway.

Function

The indirect pathway functions to inhibit movements. It is one of the two main pathways in the Basal Ganglia, the other being the Direct Pathway. The indirect pathway works in opposition to the direct pathway. While the direct pathway promotes movement, the indirect pathway inhibits unwanted or unnecessary movements.

Anatomy

The indirect pathway begins in the Striatum, which receives input from the Cerebral Cortex. From the striatum, the pathway projects to the Globus Pallidus External Segment (GPe) and the Subthalamic Nucleus (STN). The STN then sends excitatory projections to the Globus Pallidus Internal Segment (GPi) and the Substantia Nigra Pars Reticulata (SNr), which in turn send inhibitory projections to the Thalamus. The thalamus then sends excitatory projections back to the cerebral cortex, completing the circuit.

Clinical Significance

Alterations in the indirect pathway have been implicated in several neurological disorders, including Parkinson's Disease and Huntington's Disease. In Parkinson's Disease, there is a loss of dopamine in the striatum, which leads to an overactivity of the indirect pathway and an underactivity of the direct pathway. This results in the characteristic symptoms of bradykinesia and rigidity. In Huntington's Disease, there is a loss of GABAergic neurons in the striatum, which leads to an underactivity of the indirect pathway and an overactivity of the direct pathway. This results in the characteristic symptoms of chorea and hyperkinesia.

Indirect pathway Resources
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