Alpha-band desynchronization in human parietal area during reach planning.
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[Objective]The symptoms with optic ataxia suggest that simple and visually guided hand movements are controlled by 2 different neural substrates. To assess the differential frequency-coded posterior parietal cortex (PPC) role in planning visuo-motor goal-directed tasks, we studied the action specificity of event-related desynchronization (ERD) in this area. [Methods]We investigated cortical activity by electroencephalography, while 16 healthy subjects performed self-paced reaching or wrist extension (control) movements. Time–frequency representations were calculated for each movement during the preparatory period. [ResultsERD dynamics in upper alpha-band indicated that preparing a goal-directed action activates contralateral PPC to the moving hand around 1.2 s before starting the movement, while this activation is later (around 0.7 s) in preparing a not-goal-directed action. The posterior dominant rhythm had peak frequency of lower alpha-band at bilateral parietal. [Conclusions]Posterior parietal cortex encodes goal-directed movement preparation through upper alpha-band activity, whereas general attention is processed via lower alpha-band oscillations. [Significance]Preparing to reach an object engages posterior parietal cortex earlier than a not-goal directed movement.
- Clinical neurophysiology
Clinical neurophysiology 126(4), 756-762, 2015-04