Reduced Frontal Activations at High Working Memory Load in Mild Cognitive Impairment: Near-Infrared Spectroscopy

M.K. Yeung, S.L. Sze, J. Woo, T. Kwok, Ho Keung David Shum, R. Yu, A.S. Chan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

24 Citations (Scopus)

Abstract

© 2016 S. Karger AG, Basel.Background: Some functional magnetic resonance imaging studies have reported altered activations in the frontal cortex during working memory (WM) performance in individuals with mild cognitive impairment (MCI), but the findings have been mixed. The objective of the present study was to utilize near-infrared spectroscopy (NIRS), an alternative imaging technique, to examine neural processing during WM performance in individuals with MCI. Methods: Twenty-six older adults with MCI (7 males; mean age 69.15 years) were compared with 26 age-, gender-, handedness-, and education-matched older adults with normal cognition (NC; 7 males; mean age 68.87 years). All of the participants undertook an n-back task with a low (i.e., 0-back) and a high (i.e., 2-back) WM load condition while their prefrontal dynamics were recorded by a 16-channel NIRS system. Results: Although behavioral results showed that the two groups had comparable task performance, neuroimaging results showed that the MCI group, unlike the NC group, did not exhibit significantly increased frontal activations bilaterally when WM load increased. Compared to the NC group, the MCI group had similar frontal activations at low load (p > 0.05 on all channels) but reduced activations at high load (p < 0.05 on 4 channels), thus failing to demonstrate WM-related frontal activations (p < 0.05 on 9 channels). In addition, we found a positive correlation between the left WM-related frontal activations and WM ability primarily in the NC group (rs = 0.42, p = 0.035), suggesting a relationship between frontal hypoactivation and WM difficulties. Conclusion: The present findings suggest the presence of frontal dysfunction that is dependent on WM load in individuals with MCI.
Original languageEnglish
Pages (from-to)278-296
Number of pages19
JournalDementia and Geriatric Cognitive Disorders
Volume42
Issue number5-6
DOIs
Publication statusPublished - 1 Dec 2016
Externally publishedYes

Keywords

  • Aging
  • Frontal lobe
  • Mild cognitive impairment
  • n-back
  • Near-infrared spectroscopy
  • Prefrontal cortex
  • Working memory

ASJC Scopus subject areas

  • Geriatrics and Gerontology
  • Cognitive Neuroscience
  • Psychiatry and Mental health

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