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Abstract:
Motor Planning, the ability to process sequences of
movements, involves a distributed brain network that includes the
premotor cortex and basal ganglia. Little is known, however, about
cognitive planning, the ability to organize behaviors in sequences
of goals/tasks, which are not reducible to movements. Using
functional magnetic resonance imaging, we identified brain regions
and related processes underlying motor and cognitive planning in
human subjects who learned and performed sequences of movements and
tasks in an explicit procedural learning paradigm. The results show
that Broca's area (Brodmann areas 44 & 45) is uniquely involved
in processing sequences of tasks. However, when subjects gradually
internalize either motor or task sequences, common prefrontal
regions were gradually disengaged while the ventral striatum and
the rostral anterior cingulate cortex were increasingly engaged.
The ventral striatum was found to be preferentially involved in
controlling sequential progress and the rostral anterior cingulate
cortex in validating subjects sequential expectations. These
results indicate that common fronto-striatal mechanisms mediates
motor and task sequence learning, whereas Broca's area, a region
specialized in humans for language output , is also selectively
involved in processing task sequences. This suggests that aspects
of cognitive planning and language processes are mediated by
similar underlying cortical representations.
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