EEG event-related potentials in preparation, planning and execution of arm isometric exertions, localized by surface Laplacian.

Noninvasive electroencephalographic (EEG) recordings have been successfully used to study motor-related brain activity in humans. We recently used an instruction delay paradigm to investigate the EEG signatures associated with preparation, planning and execution of arm isometric exertions. Subjects (n=8), prepared, planned and exerted force with their right arm in horizontal plane, according to visual cues. Here we show that surface Laplacian, as a simple spatial filter can provide useful knowledge about the involved brain regions in different stages of the task. The results show that there is a negative peak at FCz in response to the preparation cue. The planning cue causes positive peaks at FCz and Pz followed by a sustained negativity at FCz. The GO cue leads to a a negative peak at FCz and a positive peak at Pz which is followed by a sustained positivity at C1. The results suggest that there is considerable involvement of pre-motor and parietal areas in different stages of motor preparation, planning and execution of isometric tasks. The results provide considerably local information on brain activity compared to ear-lobe referenced event-related potentials and favor the applicability of non-invasive EEG recordings and techniques to study motor neurophysiology when appropriately used in complex experimental setups. This can be of interest for different diagnostic and clinical applications and for linking the signatures of brain activity in different neuro-imaging modalities e.g. EEG and fMRI.