Transcranial magnetic stimulation of posterior parietal cortex affects decisions of hand choice
- Flavio T. P. Oliveiraa,b,1,
- Jörn Diedrichsenc,
- Timothy Verstynend,e,
- Julie Duquef, and
- Richard B. Ivrya,b
- aDepartment of Psychology and
- bHelen Wills Neuroscience Institute, University of California, Berkeley, CA 94720;
- cInstitute of Cognitive Neuroscience, University College London, London WC1N 3AR, United Kingdom;
- dCenter for the Neural Basis of Cognition and
- eLearning Research and Development Center, University of Pittsburgh, Pittsburgh, PA 15260; and
- fInstitute of Neuroscience, Université Catholique de Louvain, B-1200 Brussels, Belgium
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Edited* by Richard A. Andersen, California Institute of Technology, Pasadena, CA, and approved August 26, 2010 (received for review May 10, 2010)
Abstract
Deciding which hand to use for an action is one of the most frequent decisions people make in everyday behavior. Using a speeded reaching task, we provide evidence that hand choice entails a competitive decision process between simultaneously activated action plans for each hand. We then show that single-pulse transcranial magnetic stimulation to the left posterior parietal cortex biases this competitive process, leading to an increase in ipsilateral, left hand reaches. Stimulation of the right posterior parietal cortex did not alter hand choice, suggesting a hemispheric asymmetry in the representations of reach plans. These results are unique in providing causal evidence that the posterior parietal cortex is involved in decisions of hand choice.
Footnotes
- 1To whom correspondence should be addressed. E-mail: oflavio{at}gmail.com.
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Author contributions: F.T.P.O., J. Diedrichsen, T.V., and R.B.I. designed research; F.T.P.O. and J. Duque performed research; F.T.P.O. analyzed data; and F.T.P.O. wrote the paper.
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The authors declare no conflict of interest.
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↵*This Direct Submission article had a prearranged editor.
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This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1006223107/-/DCSupplemental.
