The Influence of Aerobic Fitness on Top-Down and Bottom-Up Mechanisms of Interference Control

Objective: Extensive evidence has demonstrated the relationship between aerobic fitness and cognitive function in early adulthood. Little is known, however, about whether the cognitive benefits of aerobic fitness are related to the modulation of top-down or bottom-up mechanisms in the control of executive attention. The present study aimed to shed light on this question by evaluating the phase-locking factor (PLF) of electroencephalogram (EEG) signal during cognitive control. Method: Higher fit and lower fit young adults performed a neuropsychological test of cognitive control (i.e., Stroop color-naming task) with concurrent EEG recording. Results: In line with previous literature, behavioral results showed that higher fit individuals performed better on the Stroop task overall. Interestingly, beta phase synchronization was larger during the incongruent condition than the congruent condition for higher fit but not for lower fit individuals, suggesting a more effective use of top-down control in the former. However, no such effect was seen for gamma activity, indicating that bottom-up mechanisms are unlikely to account for the differences in performance explained by fitness levels. Conclusion: Altogether, these findings suggest that the greater cognitive control observed in higher fit individuals is associated with differences in the control of top-down rather than bottom-up processing, consistent with the hypothesis of selective improvement. General Scientific Summary This study investigates the potential mechanism that accounts for the greater cognitive control performance associated with higher fitness levels in young adulthood. Overall, individuals with higher aerobic fitness outperformed their lower fitness counterparts on a test of cognitive control, with greater modulation of neural activity related to top-down attentional control. Although cross-sectional, the present study suggests that maintaining a high level of aerobic fitness may be associated with most efficient brains, which, in turn, may enable better goal-directed behavior, even within high-performing healthy populations.