Direct pathway of movement

Direct Pathway of Movement
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The direct pathway of movement is a critical component of the basal ganglia circuitry, which plays a significant role in the regulation of voluntary movement. This pathway is part of the complex network that includes the cerebral cortex, thalamus, and other structures within the basal ganglia.

Structure

The direct pathway begins in the cerebral cortex, where excitatory signals are sent to the striatum, a major input nucleus of the basal ganglia. The striatum consists of the caudate nucleus and the putamen. In the direct pathway, the striatum sends inhibitory signals to the internal segment of the globus pallidus (GPi) and the substantia nigra pars reticulata (SNr).

Function

The primary function of the direct pathway is to facilitate movement by reducing the inhibitory output from the GPi and SNr to the thalamus. This reduction in inhibition allows the thalamus to send excitatory signals back to the motor areas of the cortex, promoting the initiation and execution of movement.

Role in Movement Disorders

Dysfunction in the direct pathway is associated with several movement disorders. For example, in Parkinson's disease, there is a loss of dopaminergic neurons in the substantia nigra pars compacta, which leads to decreased stimulation of the direct pathway. This results in increased inhibition of the thalamus and reduced motor activity, contributing to the characteristic motor symptoms of Parkinson's disease, such as bradykinesia and rigidity.

Clinical Significance

Understanding the direct pathway is crucial for developing treatments for movement disorders. Therapies such as deep brain stimulation (DBS) target components of the basal ganglia circuitry to restore balance between the direct and indirect pathways, thereby improving motor function in affected individuals.

See Also

• Indirect pathway of movement
• Basal ganglia
• Parkinson's disease
• Deep brain stimulation

References

,

 Microcircuitry of the direct and indirect pathways of the basal ganglia, 
 Neuroscience, 
 1998, 
 Vol. 86(Issue: 2), 
 pp. 353–387, 
 DOI: 10.1016/S0306-4522(98)00004-9,

Eric R.,

 Principles of Neural Science, 
 5th edition, 
 McGraw-Hill, 
 2013, 
  
  
 ISBN 978-0071390118,

External Links

• Basal Ganglia on WikiMD
• Parkinson's Disease on WikiMD