Direct comparison of prefrontal cortex regions engaged by working and long-term memory tasks.
Neuroimaging studies have suggested the involvement of ventrolateral, dorsolateral, and frontopolar prefrontal cortex (PFC) regions in both working (WM) and long-term memory (LTM). The current study used functional magnetic resonance imaging (fMRI) to directly compare whether these PFC regions show selective activation associated with one memory domain. In a within-subjects design, subjects performed the n-back WM task (two-back condition) as well as LTM encoding (intentional memorization) and retrieval (yes-no recognition) tasks. Additionally, each task was performed with two different types of stimulus materials (familiar words, unfamiliar faces) in order to determine the influence of material-type vs task-type. A bilateral region of dorsolateral PFC (DL-PFC; BA 46/9) was found to be selectively activated during the two-back condition, consistent with a hypothesized role for this region in active maintenance and/or manipulation of information in WM. Left frontopolar PFC (FP-PFC) was also found to be selectively engaged during the two-back. Although FP-PFC activity has been previously associated with retrieval from LTM, no frontopolar regions were found to be selectively engaged by retrieval. Finally, lateralized ventrolateral PFC (VL-PFC) regions were found to be selectively engaged by material-type, but uninfluenced by task-type. These results highlight the importance of examining PFC activity across multiple memory domains, both for functionally differentiating PFC regions (e.g., task-selectivity vs material-selectivity in DL-PFC and VL-PFC) and for testing the applicability of memory domain-specific theories (e.g., FP-PFC in LTM retrieval).
Braver
T S
TS
Department of Psychology, Washington University, St Louis, Missouri 63130, USA. tbraver@artsci.wustl.edu
Barch
D M
DM
Kelley
W M
WM
Buckner
R L
RL
Cohen
N J
NJ
Miezin
F M
FM
Snyder
A Z
AZ
Ollinger
J M
JM
Akbudak
E
E
Conturo
T E
TE
Petersen
S E
SE
D000328:Adult; D001931:Brain Mapping; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D017397:Prefrontal Cortex / Q000502:physiology*; D012016:Reference Values; D012153:Retention, Psychology / Q000502:physiology*; D014706:Verbal Learning / Q000502:physiology*