Abstract
A growing body of literature provides evidence for the prophylactic influence of cardiorespiratory fitness on cognitive decline in older adults. This study examined the association between cardiorespiratory fitness and recruitment of the neural circuits involved in an attentional control task in a group of healthy older adults. Employing a version of the Stroop task, we examined whether higher levels of cardiorespiratory fitness were associated with an increase in activation in cortical regions responsible for imposing attentional control along with an up-regulation of activity in sensory brain regions that process task-relevant representations. Higher fitness levels were associated with better behavioral performance and an increase in the recruitment of prefrontal and parietal cortices in the most challenging condition, thus providing evidence that cardiorespiratory fitness is associated with an increase in the recruitment of the anterior processing regions. There was a top-down modulation of extrastriate visual areas that process both task-relevant and task-irrelevant attributes relative to the baseline. However, fitness was not associated with differential activation in the posterior processing regions, suggesting that fitness enhances attentional function by primarily influencing the neural circuitry of anterior cortical regions. This study provides novel evidence of a differential association of fitness with anterior and posterior brain regions, shedding further light onto the neural changes accompanying cardiorespiratory fitness.
Highlights
Healthy lifestyle factors are increasingly being recognized to play a critical role in the maintenance of cognitive and brain functioning through the adult lifespan (Hertzog et al, 2009)
Univariate Results Cardiorespiratory fitness and recruitment of anterior processing regions Consistent with our previous work with this paradigm examining differential recruitment of cortical regions in response to the incongruent-eligible trials relative to the incongruent-ineligible trials (Prakash et al, 2010a), we found that older adults demonstrated an inability to up-regulate cortical resources in response to the more demanding condition of the Stroop task (Figure 3)
We found that a contrast of eligible > ineligible trials resulted in greater magnitude of activation in the bilateral prefrontal cortices, including the middle and inferior frontal gyri, along with the left superior parietal lobule for higher levels of fitness, providing evidence for the fact that cardiorespiratory fitness is associated with greater recruitment of PFC and parietal resources in response to increases in task demands in older adults (Table 3; Figure 4)
Summary
Healthy lifestyle factors are increasingly being recognized to play a critical role in the maintenance of cognitive and brain functioning through the adult lifespan (Hertzog et al, 2009). We have provided evidence that increased fitness levels and participation in aerobic exercise training is associated with greater neural recruitment of regions involved in executive function including the prefrontal and the parietal cortices (Colcombe et al, 2004); and increased functional connectivity between many regions of the default-mode network (Voss et al, 2010). We are interested in examining the additional changes in neural recruitment that may accompany higher levels of fitness, thereby positively influencing cognitive performance
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