Bilateral parietal cortex function during motor imagery.

The aim of this study was to investigate the involvement of the parietal cortex during motor imagery (MI). In experiment one, participants imagined a sequence of upper limb movements during FMRI scanning. Statistical parametric mapping revealed a network of activation consistent with previous MI research, including activation in right and left inferior and superior parietal cortex. In experiment two, participants imagined a sequence of upper limb movements while real or sham single-pulse TMS was delivered over the scalp area corresponding to each individual's left or right superior parietal cortex. At the end of each trial, participants moved their upper limbs to the position that would result from executing the sequence of movements. TMS degraded accuracy of MI compared to sham stimulation, and both accuracy and confidence decreased with real and sham stimulation later in the MI sequence. The effects of TMS were similar when delivered to either hemisphere. The results of this study provide evidence of the crucial role of SPL in MI, and may have implications for rehabilitation from brain injury.