Neostriatal modulation of motor cortex excitability

Area of Science:

• Neuroscience
• Motor Control
• Basal Ganglia Function

Background:

• The basal ganglia play a crucial role in motor control.
• Understanding the basal ganglia's influence on the motor cortex is key to deciphering motor disorders.

Purpose of the Study:

• To investigate how the basal ganglia motor loop affects motor cortex excitability.
• To determine the pathway through which neostriatal activity modulates cortical function.

Main Methods:

• Pharmacologically altering neostriatal activity in ketamine-anesthetized rats.
• Monitoring motor cortex electrical stimulation thresholds.
• Utilizing intraneostriatal infusions of kainic acid and glutamate.
• Recording neuronal activity of striatonigral projection neurons.

Main Results:

• Intraneostriatal infusions of kainic acid or glutamate increased ipsilateral motor cortex thresholds.
• The effect on cortical thresholds was dependent on thalamic projections, specifically the ventrolateral thalamic nucleus.
• Inhibitory agents and saline vehicle did not alter cortical thresholds.

Conclusions:

• Neostriatal modulation of cortical thresholds occurs via thalamic pathways.
• The basal ganglia exert an inhibitory, feedforward modulation on the motor cortex and pyramidal tract.