| |
Abstract:
Studies exploring the phonological loop of working memory
have related the phonological store to the left supramarginal gyrus
and the articulatory rehearsal process to Broca's area. However,
less attention has been given to other processes of verbal working
memory, such as those linked to the modality of item presentation.
Consequently, the aim of this PET study was to explore the neural
substrates of working memory for visual or auditory verbal
information. Four cognitive tasks were administered: recall of (1)
series of five consonants perceived auditorily; (2) series of five
consonants perceived visually; (3) one consonant perceived
auditorily; (4) one consonant perceived visually. Changes in
cerebral metabolism were analysed with SPM99. Cerebral areas common
to both types of presentation are the cingulate gyrus (BA32),
middle (BA9) and inferior (BA45) frontal gyrus, left superior
parietal gyrus (BA7) and occipital areas (BA18/19). Moreover,
verbal working memory for auditorily (but not visually) presented
information involves the dorsomedial thalamus and the left inferior
parietal gyrus (BA40) while verbal working memory for visually (but
not auditorily) presented information is associated to the right
inferior frontal cortex (BA11/47), the left fusiform gyrus (BA20
and 37), and the superior parietal gyrus (BA7) bilaterally. These
results suggest that the functional network of verbal working
memory is partly dependent upon the nature of the items to be
processed.
|
