Shared brain areas but not functional connections controlling movement timing and order.

Virtually every aspect of the enormous repertoire of human behaviors is embedded in a sequential context, but brain mechanisms underlying the adjustment of two fundamental dimensions defining a motor sequence (order of a series of movements and intervals separating them) as a function of a given goal are poorly understood. Using functional magnetic resonance imaging, we demonstrate that, at the neuronal level, these tasks can only be distinguished by differences in functional interactions between associative areas of common activation, which included bilateral subcortico-parieto-frontal regions, and two subcortical structures. Activity in these shared associative areas was preferentially coupled with that in right putamen during manipulation of timing and with that in right posterior cerebellum during manipulation of serial order. This finding is important because it provides evidence for an efficient organization of the brain during cognitive control of motor sequences and supports a recently proposed principle according to which the role of brain regions involved in different behavioral tasks without differential alterations in their measured activity depends on changes in their interactions with other connected areas as a function of the tasks.