[Show abstract][Hide abstract] ABSTRACT: We investigated cerebral activation during programming of in-phase symmetric finger movements in a precued response task. Partial precues provided advance information about either mirror effectors or in-phase coordination of bimanual movements, while full precue specified both response parameters and neutral precue no movement information. Effects of precueing were assessed on reaction time (RT), contingent negative variation (CNV), and alpha and beta event-related desynchronization (ERD). Information on coordination mode induced less efficient preparation than information on effectors, as revealed by longer RT, but paradoxically the CNV was found of larger amplitude for in-phase than for mirror precue. Full and in-phase precues were associated to largest cerebral activation, as reflected by CNV amplitude as well as beta ERD. It is suggested that with in-phase precueing, abstract programming of coordination and concrete preparation of possible effectors overlap, engaging more cerebral resources than when symmetric effectors are pre-specified. Alpha ERD underwent regional modulations dependent on the type of preparation, pointing out the role of the right parietal region in visuomotor transformation with full movement programming, and the preferential implication of the dominant hemisphere and medial brain regions in synchronization of both hand movements. Beta ERD topographical distribution suggested an increased implication of bilateral and medial motor regions in anticipation to the response signal with incomplete movement preparation.
Full-text · Article · Jun 2005 · Cognitive Brain Research
[Show abstract][Hide abstract] ABSTRACT: Studies evaluating the role of the executive motor system in motor imagery came to a general agreement in favour of the activation of the primary motor area (M1) during imagery, although in reduced proportion as compared to motor execution. It is still unclear whether this difference occurs within the preparation period or the execution period of the movement, or both. In the present study, EEG was used to investigate separately the preparation and the execution periods of overt and covert movements in adults. We designed a paradigm that randomly mixed actual and kinaesthetic imagined trials of an externally paced sequence of finger key presses. Sixty channel event-related potentials were recorded to capture the cerebral activations underlying the preparation for motor execution and motor imagery, as well as cerebral activations implied in motor execution and motor imagery. Classical waveform analysis was combined with data-driven spatiotemporal segmentation analysis. In addition, a LAURA source localization algorithm was applied to functionally define brain related motor areas. Our results showed first that the difference between actual and mental motor acts takes place at the late stage of the preparation period and consists of a quantitative modulation of the activity of common structures in M1. Second, they showed that primary motor structures are involved to the same extent in the actual or imagined execution of a motor act. These findings reinforce and refine the functional equivalence hypothesis between actual and imagined motor acts.
Full-text · Article · Jan 2005 · Experimental Brain Research