Posterior compensatory network in cognitively intact elders with hippocampal atrophy

Michael J. Valenzuela*, Andrew J F Turner, Nicole A. Kochan, Wei Wen, Chao Suo, Harry Hallock, Randy A. Mcintosh, Perminder Sachdev, Michael Breakspear

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Functional compensation in late life is poorly understood but may be vital to understanding long-term cognitive trajectories. To study this we first established an empirically derived threshold to distinguish hippocampal atrophy in those with Mild Cognitive Impairment (MCI n=34) from those with proficient cognition (PRO n=22), using data from a population-based cohort. Next, to identify compensatory networks we compared cortical activity patterns during a graded spatial working memory (SWM) task in only cognitively proficient individuals, either with (PROATR) or without hippocampal atrophy (PRONIL). Multivariate Partial Least Squares analyses revealed that these groups engaged spatially distinct SWM-related networks. In those with hippocampal atrophy and under conditions of basic-SWM demand, expression of a posterior compensatory network (PCN) comprised calcarine and posterior parietal cortex strongly correlated with superior SWM performance (r=-0.96). In these individuals, basic level SWM response times were faster and no less accurate than in those with no hippocampal atrophy. Cognitively proficient older individuals with hippocampal atrophy may, therefore, uniquely engage posterior brain areas when performing simple spatial working memory tasks.

Original languageEnglish
Pages (from-to)581-593
Number of pages13
JournalHippocampus
Volume25
Issue number5
DOIs
Publication statusPublished - 1 May 2015
Externally publishedYes

Keywords

  • Compensation
  • Functional MRI
  • Hippocampus
  • Mild cognitive impairment
  • Working memory

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