A parametric fMRI investigation of context effects in sensorimotor timing and coordination

Mounting evidence suggests that information derived from environmental and behavioral sources is represented and maintained in the brain in a context-dependent manner. Here we investigate whether activity patterns underlying movements paced according to an internal temporal representation depend on how that representation is acquired during a previous pacing phase. We further investigate the degree to which context dependence is modulated by different time delays between pacing and continuation. BOLD activity was recorded while subjects moved at a rate established during a pacing interval involving either synchronized or syncopated coordination. Either no-delay or a 3, 6 or 9s delay was introduced prior to continuation. Context-dependent regions were identified when differences in neural activity generated during pacing continued to be observed during continuation despite the intervening delay. This pattern was observed in pre-SMA, bilateral lateral premotor cortex, bilateral declive and left inferior semi lunar lobule. These regions were more active when continuation followed from syncopation than from synchronization regardless of the delay length putatively revealing a context-dependent neural representation of the temporal interval. Alternatively, task related regions in which coordination-dependent differences did not persist following the delay, included bilateral putamen and supplementary-motor-area. This network may support the differential timing demands of coordination. A classic prefrontal-parietal-temporal working memory network was active only during continuation possibly providing mnemonic support for actively maintaining temporal information during the variable delay. This work provides support for the hypothesis that some timing information is represented in a task-dependent manner across broad cortical and subcortical networks.