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Neural substrates of executive dysfunction in fragile X-associated tremor/ataxia syndrome (FXTAS): a brain potential study.

Authors
  • Yang, Jin-Chen1
  • Chan, Shiao-Hui
  • Khan, Sara
  • Schneider, Andrea
  • Nanakul, Rawi
  • Teichholtz, Sara
  • Niu, Yu-Qiong
  • Seritan, Andreea
  • Tassone, Flora
  • Grigsby, Jim
  • Hagerman, Paul J
  • Hagerman, Randi J
  • Olichney, John M
  • 1 Center for Mind and Brain, University of California Davis, Davis, CA,USA.
Type
Published Article
Journal
Cerebral Cortex
Publisher
Oxford University Press
Publication Date
Nov 01, 2013
Volume
23
Issue
11
Pages
2657–2666
Identifiers
DOI: 10.1093/cercor/bhs251
PMID: 22918986
Source
Medline
Keywords
License
Unknown

Abstract

Executive dysfunction in fragile X-associated tremor/ataxia syndrome (FXTAS) has been suggested to mediate other cognitive impairments. In the present study, event-related potentials and neuropsychological testing were combined to investigate the brain mechanisms underlying the executive dysfunction in FXTAS. Thirty-two-channel electroencephalography was recorded during an auditory "oddball" task requiring dual responses. FXTAS patients (N= 41, mean age= 62) displayed prolonged latencies of N1 and P3 and reduced amplitudes of P2 and P3, whereas their N2 measures remained within the normal range, indicating relatively preserved early-stage auditory attention but markedly impaired late-stage attention and working memory updating processes (as indexed by P3). Topographical mapping revealed a typical parietal P3 peak preceded by a prominent fronto-central P3 in normal control subjects (N= 32), whereas FXTAS patients had decreased parietal P3 amplitude and diminished fronto-central positivities with a delayed onset (∼50 ms later than controls, P < 0.002). The P3 abnormalities were associated with lower executive function test (e.g., BDS-2) scores. Smaller P3 amplitudes also correlated with increased CGG repeat length of fragile X mental retardation 1 (FMR1) gene and higher FMR1 mRNA levels. These results indicate that abnormal fronto-parietal attentional network dynamics underlie executive dysfunction, the cardinal feature of cognitive impairment in FXTAS.

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