Prefrontal-parietal effective connectivity during working memory in older adults

Neurobiol Aging. 2017 Sep;57:18-27. doi: 10.1016/j.neurobiolaging.2017.05.005. Epub 2017 May 10.

Abstract

Theoretical models and preceding studies have described age-related alterations in neuronal activation of frontoparietal regions in a working memory (WM) load-dependent manner. However, to date, underlying neuronal mechanisms of these WM load-dependent activation changes in aging remain poorly understood. The aim of this study was to investigate these mechanisms in terms of effective connectivity by application of dynamic causal modeling with Bayesian Model Selection. Eighteen healthy younger (age: 20-32 years) and 32 older (60-75 years) participants performed an n-back task with 3 WM load levels during functional magnetic resonance imaging (fMRI). Behavioral and conventional fMRI results replicated age group by WM load interactions. Importantly, the analysis of effective connectivity derived from dynamic causal modeling, indicated an age- and performance-related reduction in WM load-dependent modulation of connectivity from dorsolateral prefrontal cortex to inferior parietal lobule. This finding provides evidence for the proposal that age-related WM decline manifests as deficient WM load-dependent modulation of neuronal top-down control and can integrate implications from theoretical models and previous studies of functional changes in the aging brain.

Keywords: Aging; Dynamic causal modeling (DCM); Effective connectivity; Functional magnetic resonance imaging (fMRI); Working memory.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aging / physiology*
  • Bayes Theorem
  • Female
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Memory, Short-Term / physiology*
  • Middle Aged
  • Neural Pathways / physiopathology*
  • Neuropsychological Tests
  • Parietal Lobe / diagnostic imaging
  • Parietal Lobe / physiology
  • Parietal Lobe / physiopathology*
  • Prefrontal Cortex / diagnostic imaging
  • Prefrontal Cortex / physiology
  • Prefrontal Cortex / physiopathology*
  • Young Adult