Altered brain response for semantic knowledge in Alzheimer's disease

Christina E. Wierenga, Nikki H. Stricker, Ashley McCauley, Alan Simmons, Amy J. Jak, Yu Ling Chang, Daniel A. Nation, Katherine J. Bangen, David P. Salmon, Mark W. Bondi

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Word retrieval deficits are common in Alzheimer's disease (AD) and are thought to reflect a degradation of semantic memory. Yet, the nature of semantic deterioration in AD and the underlying neural correlates of these semantic memory changes remain largely unknown. We examined the semantic memory impairment in AD by investigating the neural correlates of category knowledge (e.g., living vs. nonliving) and featural processing (global vs. local visual information). During event-related fMRI, 10 adults diagnosed with mild AD and 22 cognitively normal (CN) older adults named aloud items from three categories for which processing of specific visual features has previously been dissociated from categorical features. Results showed widespread group differences in the categorical representation of semantic knowledge in several language-related brain areas. For example, the right inferior frontal gyrus showed selective brain response for nonliving items in the CN group but living items in the AD group. Additionally, the AD group showed increased brain response for word retrieval irrespective of category in Broca's homologue in the right hemisphere and rostral cingulate cortex bilaterally, which suggests greater recruitment of frontally mediated neural compensatory mechanisms in the face of semantic alteration.

Original languageEnglish (US)
Pages (from-to)392-404
Number of pages13
JournalNeuropsychologia
Volume49
Issue number3
DOIs
StatePublished - Feb 2011

Keywords

  • Category-specific deficit
  • Dementia
  • FMRI
  • Language
  • Semantic memory
  • Word retrieval

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Cognitive Neuroscience
  • Behavioral Neuroscience

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