Differential activation of the prefrontal cortex in successful and unsuccessful memory retrieval.
Six subjects underwent PET scans while they performed three versions of a recognition memory test for words and three versions of a control task. In each memory condition, the subjects discriminated between words presented in a prescan study list and words new to the experiment. During the 30 s scanning interval, the ratio of old and new words was 0:20, 4:16 or 16:4, depending on the experimental condition. Outside this interval, the ratio was 50:50 in all three conditions. The requirement in the control task was to discriminate between two character strings, the ratios of which were also manipulated during the 30 s scanning interval. Employing the control task as a covariate, analysis with statistical parametric mapping revealed that regional cerebral blood flow (rCBF) covaried with increasing density of old items in three regions of prefrontal cortex: right dorsolateral [Brodmann area (BA) 9/46], right medial (BA 32/8) and bilateral frontopolar cortex (BA 10). It is concluded that the prefrontal cortex, especially in the right hemisphere, is more active when a retrieval attempt succeeds than when it fails. This finding is consistent with the idea that the prefrontal cortex supports processes that operate selectively on the products of memory retrieval.
Rugg
M D
MD
Wellcome Brain Research Group, School of Psychology, University of St Andrews, UK.
Fletcher
P C
PC
Frith
C D
CD
Frackowiak
R S
RS
Dolan
R J
RJ
D000328:Adult; D002560:Cerebrovascular Circulation; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D017397:Prefrontal Cortex / Q000000981:diagnostic imaging / Q000502:physiology*; D011877:Radionuclide Imaging