Lifespan changes in motor activation and inhibition during choice reactions: a Laplacian ERP study.

Response speed improves from childhood to early adulthood and declines steadily with advancing age. The present event-related brain potential (ERP) study explored the contribution of the primary motor cortex (M1) to lifespan changes in response speed and accuracy using a choice reaction time (RT) task. Two groups of children (8 and 12 years) and two groups of adults (21 and 76 years) responded to left- or right-pointing arrows. RTs showed a typical U-shaped lifespan pattern. RT was segmented into pre-selection time, pre-motor time, and motor time by using the onset of the central motor command (i.e., LRP, and the negative Laplacian potential) and the onset of response-related EMG. Pre-motor time was most sensitive to age-related change. In addition, the positive Laplacian potential, assumed to be associated with inhibition of the incorrect response alternative, was absent in children. In adults, the onset of the ipsilateral positivity started before the onset of the contralateral negativity but in elderly the onsets occurred approximately at the same time. This pattern of findings is consistent with the observed differences in choice error rates between age groups. Taken together, the lifespan changes in motor potentials point to suboptimal motor response control in children and the elderly compared to young adults.