Subthalamic nucleus stabilizes movements by reducing neural spike variability in monkey basal ganglia

Area of Science:

• Neuroscience
• Motor Control
• Basal Ganglia Function

Background:

• The subthalamic nucleus (STN) is vital for voluntary movement control, projecting to basal ganglia nuclei.
• The exact mechanisms by which the STN modulates pallidal activity and influences movement remain unclear.

Purpose of the Study:

• To investigate the role of the motor subregion of the subthalamic nucleus in controlling pallidal activity and voluntary movements.
• To elucidate the neural dynamics underlying movement control mediated by the STN-pallidum pathway.

Main Methods:

• Chemogenetics was used to reversibly reduce neural activity in the motor STN of macaque monkeys during a reaching task.
• Neural activity in the pallidum was recorded and analyzed for firing rate, spike train variability, and across-trial patterns.

Main Results:

• Reducing STN activity prolonged movement time and increased pallidal spike train variability, without significantly altering firing rate modulations.
• Irregular pallidal discharges correlated with prolonged movement duration.
• STN activity reduction led to abnormal contralateral forelimb movements, preceded by changes in STN and pallidal phasic activity.

Conclusions:

• The subthalamic nucleus plays a critical role in stabilizing pallidal spike trains, which is essential for generating stable, voluntary movements.
• Disruptions in STN function can lead to motor deficits through altered pallidal activity patterns.