Nature Neuroscience
2, 563 - 567 (1999)
doi:10.1038/9219
Role of the posterior parietal cortex in updating reaching movements
to a visual targetM. Desmurget1, 2, C. M. Epstein1, R. S. Turner1, C. Prablanc2, G. E. Alexander1
& S. T. Grafton11
Emory University School of Medicine, Department of
Neurology, Woodruff Memorial Building, Suite 6000, P.O. drawer
V, Atlanta, Georgia 30322,
USA
2
INSERM U94, Espace et Action, 16 av du
Doyen Lépine 69500 Bron, France
Correspondence should be addressed to S. T. Grafton sgrafto@emory.eduThe exact role of posterior parietal cortex (PPC) in visually directed
reaching is unknown. We propose that, by building an internal representation
of instantaneous hand location, PPC computes a dynamic motor error used by
motor centers to correct the ongoing trajectory. With unseen right hands,
five subjects pointed to visual targets that either remained stationary or
moved during saccadic eye movements. Transcranial magnetic stimulation (TMS)
was applied over the left PPC during target presentation. Stimulation disrupted
path corrections that normally occur in response to target jumps, but had
no effect on those directed at stationary targets. Furthermore, left-hand
movement corrections were not blocked, ruling out visual or oculomotor effects
of stimulation.
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