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Abstract:
Abstract: Retention processes in visual working memory are
realized by a neuronal network including prefrontal, premotor and
parietal cortical areas. We used fMRI to specify the functional
role of the lateral premotor cortex in this network. Previous
studies suggest that the lateral premotor cortex can be activated
by viewing graspable objects in the absence of any overt motor
demands. Here we examined, whether the lateral premotor cortex is
stronger activated when manipulable relative to non-manipulable
objects have to be maintained in working memory. Participants
performed a delayed matching task, that allowed to contrast the
activation pattern for both groups of objects held in working
memory, independently of encoding and/or decision processes. For
manipulable objects significant left lateral premotor activation
was found, located in a region previously found in correlation with
imaging hand movements and naming tool use. This suggests that
motor schemata for object use are activated when graspable objects
are maintained in working memory. Conversely, rather than the
lateral premotor cortex non-manipulable objects recruited the left
fronto-opercular cortex (Broca's area) during retention, suggesting
that phonological recoding and rehearsal takes place for the latter
objects. The results indicate a differential involvement of hand
motor and verbal motor representation in working memory depending
on the motor valence of the to be memorized objects.
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