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Abstract:
It has been convincingly demonstrated that patients with
semantic dementia (the temporal variant of frontotemporal dementia)
can show intact recognition memory for pictorial stimuli. As yet,
the contribution made by recollective processes to this ability,
and the status of associated neural regions, have not been
investigated in the disease. Here, we used both a source monitoring
paradigm and an associative memory test to evaluate the ability of
patients with semantic dementia to utilise recollection-based
memory processes, and a volumetric MRI technique to assess the
extent of atrophy in medial temporal lobe regions. Although some
patients showed impaired recollection-based memory, others
performed as well as control participants. There was no positive
correlation between recollection and volume of the hippocampus;
instead, both source discrimination and associative memory
correlated highly with performance on a battery of frontal lobe
tests. Consistent with the view that damage to prefrontal cortex
might influence recollection performance, patients with the frontal
variant of frontotemporal dementia, with atrophy largely confined
to the frontal lobes, all performed at floor levels on source
discrimination. These results are interpreted in the light of
current theories about the cognitive and neural organisation of
long-term memory systems.
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