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Abstract:
Findings that brain lesions have selective effects on
specific memory functions constitute a fundamental basis for the
classification of memory into separate systems. More recently,
functional neuroimaging techniques have also been used to map
differences in brain activity associated with measures of different
systems. Considerable less attention has been devoted to the issue
of discovering similarities in activation patterns between systems.
A related under-explored issue concerns analysis of differences in
activation patterns between measures assumed to reflect the same
system. The goal of the present study was to investigate between-
and within-systems similarities and differences in brain activity
as measured by PET. The study included 14 subjects and 7
experimental conditions (each condition was scanned twice): (1)
cued recall, (2) autobiographical memory, (3) fact retrieval, (4)
synonym retrieval, (5) one-back test, (6-7) read same or different
word. A multivariate analysis revealed similarities between
episodic and semantic memory by showing that conditions 1-4
involved increased activity in left inferior frontal and anterior
cingulate regions. Evidence for within-system differences was
provided by a finding of increased activity in right prefrontal and
bilateral parietal regions during cued recall compared to all other
conditions, including autobiographical memory. It is concluded that
the organization of memory in the brain is more complex than is
suggested by contemporary taxonomies of memory.
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