Orienting movements in area 9 identified by long-train ICMS

Area of Science:

• Neuroscience
• Primate behavior
• Motor control

Background:

• Previous microstimulation studies focused on frontal eye and premotor ear-eye fields.
• Area 9 in the frontal pole lacked microstimulation research regarding its functional role.

Purpose of the Study:

• Investigate the effects of electrical microstimulation on area 9 in macaque monkeys.
• Determine the role of area 9 in motor control, specifically ear and eye movements, and head force generation.

Main Methods:

• Electrical microstimulation applied to area 9 in two macaque monkeys.
• Stimulation used long-train pulses (500-1000 ms) under spontaneous and visual fixation conditions.
• Recorded backward ear movements, goal-directed eye movements, and head forces.

Main Results:

• Kinematic parameters for ear and eye movements differed between spontaneous and visual fixation tasks.
• During visual fixation, ear movement amplitude and duration increased, while eye movement parameters decreased.
• Longest stimulation trains (800/1000 ms) induced maximal eye amplitude and significant head forces.

Conclusions:

• Top-down visual attention engagement can modulate kinematic parameters of ear and eye movements.
• Area 9 may be involved in the control of goal-directed orienting behaviors and gaze shift control.
• Proposes a new perspective on the function of frontal oculomotor fields, including area 9.