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Abstract:
We sought to investigate the role of instruction in motor
sequence learning. Specifically, we examined the effect of prior,
partial knowledge of rules governing a repeating sequence while
employing a novel variant of the serial reaction time task (SRTT).
Nine subjects underwent whole-brain functional magnetic resonance
imaging (fMRI) at 3T while learning two 12-element repeating
sequences. Each subject learned one sequence implicitly, and a
second following instruction on one of three rules governing the
sequence. Behaviorally, subjects showed significant response-time
decreases across both types of learning blocks. Brain regions
activated by each learning mode, as compared to resting baseline,
were consistent across subjects and included contralateral motor
cortices, basal ganglia and thalamus, ipsilateral cerebellum, and
bilateral BA7 (all: p<1e-9). When examining monotonic activation
changes, group analyses identified multiple regions involved in
both types of learning: right hippocampus, cerebellum, and
BA21/BA22, and bilateral BA47. Differences included left BA20/BA21,
and bilateral BA8 and BA10--regions previously identified with rule
learning. Our results demonstrate that different but overlapping
neuronal networks are engaged by these two learning tasks,
including differential reliance on orbitofrontal cortex. We believe
this work has implications for motor rehabilitation following brain
injury.
Supported by the McDonnell-Pew Program in Cognitive
Neuroscience JSMF#97-33.
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