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Abstract:
An important issue in working memory research is whether
different cortical regions support the maintenance of different
types of information. While meta-analyses of neuroimaging data have
revealed dissociations between verbal and spatial working memory,
these dissociations have not been widely confirmed using
within-subject designs. We approach this issue by asking native
Chinese-speaking subjects to encode and retrieve verbal information
from working memory, while we manipulate the effectiveness of
phonologically-based rehearsal. Specifically, we take advantage of
the large number of Chinese characters with similar pronunciations
to contrast the brain regions that are active during a delayed
serial recall task when subjects are presented with a set of six
phonologically distinct Chinese characters, versus six homophones.
We hypothesized that brain regions associated with a
phonologically-based rehearsal strategy would be more active in the
non-homophone than in the homophone condition, whereas regions
associated with orthographic and semantic processing might show the
opposite pattern of activation. Our preliminary results support
this hypothesis: for example, Broca's area, a region associated
with articulatory control processes, showed higher
maintenance-related activation for non-homophones as compared to
homophones. More generally, our findings point towards an approach
to identifying domain-specific processes in working memory that
complements more commonly employed manipulations of material
type.
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