M.C. van de Laar

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.

Development of response activation and inhibition in a selective stop-signal task.

To gain more insight into the development of action control, the current brain potential study examined response selection, activation, and selective inhibition during choice- and stop-signal processing in three age groups (8-, 12-, and 21-year-olds). Results revealed that age groups differed in the implementation of proactive control; children slowed their go response and showed reduced cortical motor output compared to adults. On failed inhibition trials, children were less able than adults to suppress muscle output resulting in increased partial-inhibition rates. On invalid stop trials, all age groups initially activated, subsequently inhibited, and then reactivated the go response. Yet, children were less efficient in implementing this strategy. Then, older children recruit motor responses to a greater extent than younger children and adults, which reduced the efficiency of implementing response inhibition and proactive control. The results are discussed in relation to current notions of developmental change in proactive and reactive action control.To gain more insight into the development of action control, the current brain potential study examined response selection, activation, and selective inhibition during choice- and stop-signal processing in three age groups (8-, 12-, and 21-year-olds). Results revealed that age groups differed in the implementation of proactive control; children slowed their go response and showed reduced cortical motor output compared to adults. On failed inhibition trials, children were less able than adults to suppress muscle output resulting in increased partial-inhibition rates. On invalid stop trials, all age groups initially activated, subsequently inhibited, and then reactivated the go response. Yet, children were less efficient in implementing this strategy. Then, older children recruit motor responses to a greater extent than younger children and adults, which reduced the efficiency of implementing response inhibition and proactive control. The results are discussed in relation to current notions of developmental change in proactive and reactive action control.