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Abstract:
Abstract: The medial temporal lobes play a central role in
the consolidation of new memories. Medial temporal lesions impair
episodic learning in amnesia, and disrupt vocabulary acquisition.
To investigate the role of consolidation processes in phonological
memory, and to understand where and how, in amnesia, these
processes begin to fail, we re-examined phonological memory in the
amnesic patient HM. Whilst HM's word span performance was normal,
his supra-span recall was shown to be markedly impaired, with his
recall characterized by a distinctive pattern of phonological
errors, where HM would frequently recall a similar sounding word,
not present in the original list (e.g., life tramp). As a group,
the Korsakoff patients showed a similar but less marked pattern.
Previous studies have linked the presence of phonological errors in
immediate serial recall to deficits in long-term memory
representations (Patterson, Graham & Hodges, 1994; Knott,
Patterson & Hodges, 1997). HM nevertheless continued to show
good online comprehension of content words. To account for the
error patterns seen in HM and the Korsakoff patients, we propose a
model of phonological memory which explicitly links HM's abnormal
performance on supra-span list recall to his anterograde amnesia.
The model also provides a natural explanation for why, since the
onset of his amnesia, HM has been unable to learn significant
amounts of new vocabulary.
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