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Abstract:
Abstract: We used event-related functional magnetic resonance
imaging to investigate brain regions showing differential responses
as a function of confidence in an episodic word recognition task.
Twelve healthy volunteers indicated whether their old-new judgments
were made with high or low confidence. Haemodynamic responses
associated with each judgment were modeled with an early and a late
response function. As predicted by the monitoring hypothesis
generated from a previous recognition study (Henson et al., 1999),
a right dorsolateral prefrontal region showed a greater response to
correct low versus correct high confidence judgements. This
difference was apparent with both early and late response
functions, suggesting that monitoring processes were prolonged in
time. Several regions, including precuneus, posterior cingulate and
left lateral parietal cortex, showed greater early responses to
correct old than correct new judgements. Anterior left prefrontal
and cingulate regions also showed this effect, but the old-new
difference emerged relatively later in time. A right anterior
prefrontal region, not implicated in our previous study, also
showed a relatively delayed old-new effect. These results further
support the proposal that different subregions of right prefrontal
cortex subserve different functions during episodic retrieval.
These functions are discussed in relation to a monitoring process,
operating when familiarity-levels are close to response criterion
and associated with less confident judgements, and a recollective
process, associated with confident recognition of old words.
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