B. Rypma et M. D'Esposito, The roles of prefrontal brain regions in components of working memory: Effects of memory load and individual differences, P NAS US, 96(11), 1999, pp. 6558-6563
Citations number
35
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Using an event-related functional MRI design, we explored the relative role
s of dorsal and ventral prefrontal cortex (PFC) regions during specific com
ponents (Encoding, Delay, Response) of a working memory task under differen
t memory-load conditions. In a group analysis, effects of increased memory
load were observed only in dorsal PFC in the encoding period. Activity was
lateralized to the right hemisphere in the high but not the low memory-load
condition. Individual analyses revealed variability in activation patterns
across subjects. Regression analyses indicated that one source of variabil
ity was subjects' memory retrieval rate. It was observed that dorsal PFC pl
ays a differentially greater role in information retrieval for slower subje
cts, possibly because of inefficient retrieval processes or a reduced quali
ty of mnemonic representations. This study supports the idea that dorsal an
d ventral PFC play different roles in component processes of working memory
.