This discussion summarizes the relatively well-established scientific literature using cross-sectional, longitudinal, observational, and randomized controlled trials examining the effect of physical activity or cardiorespiratory fitness on regional gray matter volume. These studies have consistently

reported that higher fitness levels are associated with larger brain volumes, and that participation in only modest amounts of physical activity is sufficient for increasing gray matter volume in select brain regions. In addition, these results are in line with the animal literature and human cognitive literature described in preceding sections demonstrating the brain plasticity Inhibitors,research,lifescience,medical and specificity of the effects of greater amounts of physical activity. Volumetric data has proven useful in identifying how physical activity could alter the morphology of the adult brain. However, other neuroimaging methods including functional magnetic resonance imaging (fMRI) and resting state connectivity (rs) MRI approaches allow for an investigation of the Inhibitors,research,lifescience,medical effects of physical activity on brain network dynamics. In one of the earliest studies to examine this, Colcombe et al43 employed a task measuring selective attention and executive

control in a two-part Inhibitors,research,lifescience,medical experiment. In the first experiment, higher cardiorespiratory fitness levels were associated with better performance on the task and this was paralleled by increases in fMRI activity Inhibitors,research,lifescience,medical in the dorsolateral prefrontal and parietal

brain regions. The second experiment was a randomized exercise intervention in which adults were assigned to either receive a structured exercise regimen for 6 months or to a stretching and click here toning control group for the same amount of time. The participants performed the same selective attention task as the participants in the first experiment. The results from the randomized trial were strikingly similar to the results from the crosssectional Inhibitors,research,lifescience,medical study. That is, after 6 months of the intervention, the exercise group showed increased activity in the dorsolateral prefrontal cortex and parietal cortex and decreased activity in areas that support conflict monitoring such as the anterior cingulate cortex. These results are important because they demonstrate that in addition to volumetric changes resulting from exercise there are also significant changes in task-evoked brain function. Hence, the brain processes all task demands more efficiently after only 6 months of exercise. Although there are only several published studies using fMRI paradigms, each of these studies has found increased fMRI activity in prefrontal regions including during a semantic memory task,44 the digit symbol substitution task,45 and the Stroop task46 as a function of either higher cardiorespiratory fitness levels or greater physical activity levels.