The fan effect in fMRI: left hemisphere specialization in verbal working memory.
We studied the fan effect of verbal working memory using functional magnetic resonance imaging (fMRI). Participants were presented with a sentence-pair matching task that described semantic relationships (e.g. classroom-school). Working memory load and semantic processing were manipulated by increasing the number of sentences to be remembered and varying whether they matched expectation. Increased working memory load elicited activation in left dorsal frontal and left inferior parietal regions, and also delayed the hemodynamic responses. Convergent results from semantic matches occurred in the left parietal lobe, whereas, left ventral frontal activation from mismatches diverged from working memory results. The findings were consistent with behavioural and electrophysiological evidence, with the fan effect in fMRI providing novel insight into the spatiotemporal nature of verbal working memory in the left hemisphere.
National Research Council, Institute for Biodiagnostics, Dalhousie University, Halifax Infirmary, Suite 3900, 1796 Summer Street, Halifax, NS B3 H 3A7, Canada. Ryan.D'Arcy@nrc-cnrc.gc.ca
Ryan C N
RC
D'Arcy
Lawrence
L
Ryner
Wolfgang
W
Richter
Elisabet
E
Service
John F
JF
Connolly
D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000098:blood supply / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation / Q000379:methods; D012660:Semantics; D012691:Serial Learning / Q000502:physiology; D014706:Verbal Learning / Q000502:physiology*; D014936:Word Association Tests / Q000706:statistics & numerical data
D010100:Oxygen