Gaze-Dependent Deviation in Pointing Induced by Transcranial Magnetic Stimulation Over the Human Posterior Parietal Cortex

Abstract

Signals arising from the saccadic system influence the planning and generation of pointing movements, and the posterior parietal cortex (PPC) appears to play a vital role in that interaction. The authors demonstrate in the present study that during visual fixation, eye-position signals can dominate pointing responses when the activity in the PPC contralateral to the moving limb is disrupted with transcranial magnetic stimulation (TMS). In particular, when presented with targets in peripheral vision, participants (N = 5) exposed to TMS over the PPC failed to show the normal pattern of responses in which pointing movements end up farther away from the goal target. Instead, they tended to point more toward the current point of visual fixation. Those results suggest that the PPC is involved in integrating eye-position and visual information to affect reaching in the contralateral arm.

Keywords:

• pointing movements
• posterior parietal cortex
• saccadic eye movements
• vision