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Abstract:
Abstract: Both lateral prefrontal cortex (LPFC) and
temporo-parietal cortex have been implicated in working memory in
neuroimaging studies. It was of interest to compare patients with
lesions centered in these regions on a variety of verbal and
non-verbal short-term memory tasks. We studied two groups of left
hemisphere patients: 1) patients with focal LPFC lesions and 2)
patients with conduction aphasia (CA) with lesions in
temporo-parietal cortex. We previously reported that, compared to
frontal lobe patients, patients with CA are impaired on short-term
memory tasks that involve rehearsing auditory-verbal material, even
when the response is non-verbal (e.g. pointing). Frontal lobe
patients, however, show moderately impaired performance on
non-verbal span tasks, such as the Corsi pointing test. In the
current study, participants performed a rhyme judgment task, in
which two words were presented visually and were separated by 3
different ISIs (500ms, 1000ms, 2000ms). Overall, patients with CA
performed worse on this task, compared to controls and LPFC
patients. Also, patients with CA performed most poorly when the
rhyme pair was related in a non-orthographic fashion (e.g. mail ..
sale), compared to orthographically related pairs (e.g. talk ..
chalk). We are currently repeating this experiment with auditory
presentation. The working hypothesis is that LPFC supports
performance on working memory tasks because of its role in
attention/executive processes, while temporo-parietal cortex
supports temporary storage of auditory-verbal material.
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