Cardiovascular fitness, cortical plasticity, and aging

Abstract

Cardiovascular fitness is thought to offset declines in cognitive performance, but little is known about the cortical mechanisms that underlie these changes in humans. Research using animal models shows that aerobic training increases cortical capillary supplies, the number of synaptic connections, and the development of new neurons. The end result is a brain that is more efficient, plastic, and adaptive, which translates into better performance in aging animals. Here, in two separate experiments, we demonstrate for the first time to our knowledge, in humans that increases in cardiovascular fitness results in increased functioning of key aspects of the attentional network of the brain during a cognitively challenging task. Specifically, highly fit (Study 1) or aerobically trained (Study 2) persons show greater task-related activity in regions of the prefrontal and parietal cortices that are involved in spatial selection and inhibitory functioning, when compared with low-fit (Study 1) or nonaerobic control (Study 2) participants. Additionally, in both studies there exist groupwise differences in activation of the anterior cingulate cortex, which is thought to monitor for conflict in the attentional system, and signal the need for adaptation in the attentional network. These data suggest that increased cardiovascular fitness can affect improvements in the plasticity of the aging human brain, and may serve to reduce both biological and cognitive senescence in humans.

Figures

Fig. 1.

Studies 1 and 2 used a slow-event-related fMRI design. Participants were presented with a 13.5-sec fixation cross, which was followed by a 500-ms pre cue that informed participants that the critical stimulus was about to appear. Finally, an array of five arrows appeared on the screen. Participants were asked to respond to the orientation of the central arrow by pressing a button with their left hand if the arrow pointed to the left, and with their right hand if the arrow pointed to the right. On half of the trials, the flanking arrows faced in the same direction as the central cue (congruent trials), and on the other half, they pointed in the opposite direction (incongruent trials). These stimuli remained on the screen for 2,000 ms.

Fig. 2.

Regional differences in cortical recruitment as a function of cardiovascular fitness. See Table 1 for cluster descriptions.