Visual and oculomotor functions of monkey subthalamic nucleus

Area of Science:

• Neuroscience
• Primate behavior
• Motor control

Background:

• The subthalamic nuclei play a crucial role in motor control and decision-making.
• Understanding the neural activity within the subthalamic nuclei during complex tasks is essential for elucidating brain function.

Purpose of the Study:

• To investigate the activity of single neurons in the subthalamic nuclei during various visuooculomotor tasks in monkeys.
• To classify task-related neuronal activity, including fixation, saccades, visual responses, and reward anticipation.

Main Methods:

• Single-unit recordings were performed in the subthalamic nuclei of three monkeys during fixation, visually guided saccade, and memory-guided saccade tasks.
• Neuronal activity was analyzed in relation to specific task events, including visual stimuli, eye movements, and reward delivery.

Main Results:

• Ninety-five out of 265 recorded neurons exhibited task-related activity, categorized into fixation-related, saccade-related, visual stimulus-related, target- and reward-related, and lever release-related.
• Fixation-related activity showed sustained discharge during target fixation, while saccade-related activity displayed phasic increases time-locked with saccades.
• Visual responses exhibited phasic excitation with latencies of 70-120 ms, and target/reward-related activity involved sustained discharge linked to expected rewards.

Conclusions:

• The subthalamic nuclei contain neurons with diverse response properties relevant to visuooculomotor control and reward processing.
• Specific neuronal populations in the subthalamic nuclei encode distinct aspects of task performance, contributing to goal-directed behavior.