Adaptation of brain functional and structural networks in aging.

Annie Lee,Nagulan Ratnarajah,Shen-Hsing Annabel Chen,Anqi Qiu,Ta Anh Tuan

doi:10.1371/journal.pone.0123462

Abstract

The human brain, especially the prefrontal cortex (PFC), is functionally and anatomically reorganized in order to adapt to neuronal challenges in aging. This study employed structural MRI, resting-state fMRI (rs-fMRI), and high angular resolution diffusion imaging (HARDI), and examined the functional and structural reorganization of the PFC in aging using a Chinese sample of 173 subjects aged from 21 years and above. We found age-related increases in the structural connectivity between the PFC and posterior brain regions. Such findings were partially mediated by age-related increases in the structural connectivity of the occipital lobe within the posterior brain. Based on our findings, it is thought that the PFC reorganization in aging could be partly due to the adaptation to age-related changes in the structural reorganization of the posterior brain. This thus supports the idea derived from task-based fMRI that the PFC reorganization in aging may be adapted to the need of compensation for resolving less distinctive stimulus information from the posterior brain regions. In addition, we found that the structural connectivity of the PFC with the temporal lobe was fully mediated by the temporal cortical thickness, suggesting that the brain morphology plays an important role in the functional and structural reorganization with aging.

Highlights

Converging evidence from task-based functional magnetic resonance imaging studies suggests pronounced aging effects on functional activities in the prefrontal cortex (PFC)
The age-related PFC findings were partially mediated by age-related increases in the structural connectivity of the occipital lobe within the posterior regions of the brain, suggesting that the reorganization of the PFC structural connectivity with aging could be partly due to the adaptation to age-related changes in the reorganization of the posterior regions of the brain
This supports the idea derived from task-based functional magnetic resonance imaging (fMRI) that the PFC reorganization in aging may be adapted to the need of compensations for resolving less distinctive stimulus information from the posterior brain regions

Summary

Introduction

Converging evidence from task-based functional magnetic resonance imaging (fMRI) studies suggests pronounced aging effects on functional activities in the prefrontal cortex (PFC). The age-related increase in bilateral frontal activation seemed to suggest that older adults were working harder and engaging in more distributed brain regions. Posterior regions of the brain often show age-related reduction in functional responses and dedifferentiation to stimuli [2, 8,9,10,11,12,13,14]. In older adults, these brain regions tend to lose these functional specificities. This decrease in neural specificity was thought of as dedifferentiation such that a given region that responds selectively in young adults will respond to a wider array of inputs in older adults

Methods

Results

Conclusion