Sl. Thompson-schill et al., Effects of repetition and competition on activity in left prefrontal cortex during word generation, NEURON, 23(3), 1999, pp. 513-522
Neuroimaging studies have revealed an association between word generation a
nd activity in the left inferior frontal gyrus (IFG) that is attentuated wi
th item repetition. The experiment reported here examined the effects of re
peated word generation, under conditions in which completion was either dec
reased or increased, on activity measured during whole-brain echoplanar fun
ctional magnetic resonance imaging. Activity in left IFG decreased during r
epetition conditions that reduced competition but increased during repetiti
on conditions that increased competition; this pattern was contrasted to re
petition effects observed in other cortical areas, specifically regions of
left temporal cortex. The increase in left IFG activity, which is not predi
cted by a simple semantic retrieval account of prefrontal function, is cons
istent with the hypothesis that left IFG subserves the selection of semanti
c knowledge among competing alternatives.