Identification of the brain networks that contribute to the interaction between physical function and working memory: An fMRI investigation with over 1,000 healthy adults

Toru Ishihara,Atsushi Miyazaki,Hiroki Tanaka,Tetsuya Matsuda

doi:10.1016/j.neuroimage.2020.117152

Abstract

There is a growing consensus regarding the positive relationship between physical function and working memory; however, explanations of task-evoked functional activity regarding this relationship and its differences in physical function domains remain controversial. This study illustrates the cross-sectional relationships between cardiorespiratory fitness, gait speed, hand dexterity, and muscular strength with working memory task (N-back task) performance and the mediating effects of task-evoked functional activity in 1033 adults aged between 22 and 37 years. The results showed that cardiorespiratory fitness and hand dexterity were independently associated with N-back task performance to a greater extent and in contrast to gait speed and muscular strength. These relationships were mediated by task-evoked functional activity in a part of the frontoparietal network (FPN) and default mode network (DMN). Superior cardiorespiratory fitness could contribute to working memory performance by enhancing the compensational role of FPN-related broader region activation. Hand dexterity was associated with moderation of the interaction in terms of task-evoked activation between the FPN and DMN, which in turn, improved N-back task performance. Based on these findings, we conclude that cardiorespiratory fitness and hand dexterity have common and unique mechanisms enhancing working memory.

Highlights

Working memory is an aspect of cognitive control that is defined as “the ability to hold information in mind and mentally work with it”(Diamond, 2013)
Additional studies examining the relationship between physical function and functional brain networks at rest (Talukdar et al, 2018; Voss et al, 2016) have shown that cardiorespiratory fitness has a positive relationship with the resting-state functional connectivity of the frontoparietal network (FPN), including the activated bilateral dorsal and ventral prefrontal cortex (PFC), dorsal parietal cortex, and dorsal anterior cingulate, as well as activation in the default mode network (DMN), including the medial PFC, posterior cingulate, and occipital–parietal junction
Correlation analysis showed that performances regarding cardiorespiratory fitness, hand dexterity, and muscular strength were positively associated with the 2-back task accuracy

Summary

Introduction

Working memory is an aspect of cognitive control that is defined as “the ability to hold information in mind and mentally work with it”(Diamond, 2013). Over the last two decades, there has been a growing consensus regarding the relationship between higher levels of physical function via regular physical exercise and improved working memory performance regardless of age (Kamijo et al, 2011; Kao et al, 2017; Kramer and Colcombe, 2018; Ludyga et al, 2020; Scudder et al, 2016; Voelcker-Rehage et al, 2010). Several previous studies utilizing magnetic resonance imaging (MRI) have reported that structural brain changes in the prefrontal cortex (PFC) may be related to the positive correlation between physical function and working memory (Kramer and Colcombe, 2018; Oberlin et al, 2016; Raichlen et al, 2016; Voss, 2010; Voss et al., 2013a; Wittfeld et al, 2020). Additional studies examining the relationship between physical function and functional brain networks at rest (Talukdar et al, 2018; Voss et al, 2016) have shown that cardiorespiratory fitness has a positive relationship with the resting-state functional connectivity of the frontoparietal network (FPN), including the activated bilateral dorsal and ventral PFCs, dorsal parietal cortex, and dorsal anterior cingulate, as well as activation in the default mode network (DMN), including the medial PFC, posterior cingulate, and occipital–parietal junction

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