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Abstract:
Functional magnetic resonance imaging was used to examine the
changes in brain activity that coincide with the learning of
paired-associates for two distinct material types; verbal and
nonverbal. In the verbal version of the task, subjects learned to
associate semantically unrelated low-imagability words. In the
nonverbal version, subjects learned to associate abstract polygonal
objects. We hypothesized that, across material types, early
learning would be mediated by a network of shared brain regions,
while practiced performance would be associated with primarily
material-dependent activations. Regions involved in early and
practiced task performance were identified by contrasting fMRI
signal elicited during performance with novel and studied pairs to
that of a low-level control condition. Areas showing
learning-related change were then identified by directly comparing
signal associated with novel pairs to that for studied pairs. These
comparisons were made independently for each material type, and the
resulting maps were analyzed for their correspondence across
materials. This examination revealed a set of regions, including
prefrontal, cingulate, and parietal areas, exhibiting activity
during early performance with both the verbal and nonverbal pairs,
but showing reduced levels of activation in practiced performance
for both types. These findings suggest that a common network of
brain regions may underlie learning across material types and
domains.
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