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Abstract:
The examination of false memories provides important insights
into the cognitive and neuronal aspects of memory retrieval.
However, previous studies comparing correct and false recognition
have revealed mixed patterns of results. We examined ERPs and
event-related fMRI responses to correctly recognized words and
false recognitions of associatively related words (lures) in two
experiments using randomly intermixed item types. Response times
were larger for lures than for correct old and new responses and
the false alarm rates to lures were around 30%. The ERP responses
to old words were dissociable from new words and from lures between
400 and 700 ms. In a late time interval (800-1600ms), both old
words and lures evoked frontal positive slow waves, an effect which
previous studies have attributed to post-retrieval monitoring
processes. Differential brain activation patterns for old words and
lures were also obtained in the fMRI experiment. Only old words
activated the middle frontal gyrus and the nucleus accumbens,
whereas only lures led to activations along the banks of the
cingulate sulcus. The combined ERP and fMRI results provide
evidence for temporally and spatially dissociable brain activity
for correct and false recognition. They also support the prominent
role of prefrontal brain regions and possibly also the basal
forebrain in recollecting old information. The cortex along the
cingulate sulcus may play a role in effortful discrimination
processes
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