Brain activity correlates differentially with increasing temporal complexity of rhythms during initialisation, synchronisation, and continuation phases of paced finger tapping

Force related activations in rhythmic sequence production

“…However, we observed no reliable activity for conditions where responses were separated by alternating compared with equal intervals-there was no main effect of alternating interval. Other imaging studies have reported reliable activation of a number of structures including BG and cerebellum in a comparison of alternating and equal interval production in an evaluation of learning (Doyon et al, 2003) and in a parametric analysis of rhythm complexity in well-learned performance (Lewis et al, 2004). However, in the former, the differential subcortical activation dissipated in well-practiced performance and in the latter, parametric subcortical activation effects were limited to initial preparation and synchronization phases of each trial and were not present during unpaced responding.…”

“…In previous timing studies, the possibility of differential difficulty across conditions has been an issue because observed effects might be attributed to processes responsible for allocation of attention rather than to greater involvement of the process itself. For instance, Lewis et al (2004) noted increased fronto-parietal involvement with more complex rhythms and this could have reflected either greater demands on brain regions responsible for timing or increased demand on attentional circuits. However, in the present study, it seems less likely that the subcortical foci of activation associated with alternation of force but not interval should be identified with attention control and we therefore suppose the activated regions directly reflect the control of force.…”

“…In our study, activation measures were taken in unpaced responding. Extrapolating from our earlier study (Lewis et al, 2004) which did not control force, we expected that while alternating force levels might activate basal ganglia compared to equal force conditions, there would be no differential activation for alternating response intervals compared to equal interval conditions.…”

“…A few of these included patterned variation of inter-response intervals to investigate structures involved in rhythm (Penhune et al, 1998;Lewis et al, 2004), but no study that we are aware of has manipulated force as part of rhythm. In practiced performance, parametric variation in rhythm complexity (defined by the number of different intervals) related to activation levels in cerebellum, BG, and also to cortical regions, but only in the initial synchronization phase of each trial and not during unpaced responding (Lewis et al, 2004).…”

Tapping with intentional drift

“…In that case, any perceived difficulty due to planning would not transfer to tapping behavior. A recent study by Lewis et al (2004) supports this interpretation as initiation, synchronization, and continuation were found to be affected in different ways during the performance of tasks with different degrees of difficulty. On the other hand, because our subjects had no musical training, it is possible that they were not able to make on-line corrections during their performance.…”