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TMS investigations of memory-guided reaching in human posterior parietal cortex| old_uid | 5335 |
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| title | TMS investigations of memory-guided reaching in human posterior parietal cortex |
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| start_date | 2008/10/06 |
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| schedule | 16h |
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| online | no |
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| summary | Dorsal posterior parietal cortex (PPC) has been implicated through single-unit recordings, neuroimaging data, and studies of brain-damaged humans in the spatial guidance of reaching and pointing movements. I will describe a series of transcranial magnetic stimulation (TMS) studies exploring the role of the human PPC in memory-guided reaching. In a first study, we examined the causal effect of single-pulse TMS over the left and right dorsal-lateral PPC during a memory-guided ‘reach-to-touch’ movement task. We show that induction of a focal current reveals a hemispheric asymmetry in the early stages of the putative spatial processing in PPC. In the second part of this talk, I will describe new findings showing that these TMS-induced errors significantly decreased with visual feedback of the hand during both planning and control stages of the reach movement. These new findings demonstrate that 1) visual feedback of hand position during the planning and early execution of the reach can recalibrate this perturbed signal and, more importantly, 2) TMS over dorsal-lateral PPC does not disrupt the internal representation of the visual goal, but rather the reach vector, or more likely the sense of initial hand position that is used to calculate this vector. Finally, I will discuss on-going work from our lab. |
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| responsibles | Farnè, Béranger, Soulier |
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