Examining the Impact of Exercise-Cognition Interactions on Neural Plasticity in Humans

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Exercise is a powerful stimulus for physiological adaptations that improve physical function. However, the impact of those physiological adaptions on human cognition is not well understood. A recent discovery made by my lab and others is that the impact of exercise on cognition is domain specific - targeting functions of memory and executive functions. Although researchers have been unable to explain this domain specificity, my recent NSERC-funded research offers new insights by identifying vigorous exercise as a potent stimulus for neural plasticity over lighter modes of exercise. What is so special about vigorous exercise? During vigorous exercise, the muscles require oxygen faster than can be delivered. Anaerobic metabolism kicks in to cover the shortfall and this causes excess L-lactate. Although lactate was historically regarded as an inert metabolic by-product, new research from animal models suggests that lactate may promote neural plasticity. This has yet to be fully tested in humans and will be an important contribution of the proposed research. Furthermore, exercise-induced plasticity may be augmented by cognitive training. Although cognitive training is not physically challenging (and does not increase lactate), it is mentally challenging and thus, adds to the total stress burden that is registered by the brain. The proposed research will use orienteering-based training, which is the closest evolutionary surrogate for hunter-gatherer activities, to combine spatial navigation with high-intensity exercise to determine how the physiological adaptations from exercise interact with those from cognitive training to alter the human brain. OBJECTIVES: Using the neurobiology of stress as a model, my research aims to understand the mechanisms underlying the domain-specific effects of exercise on the human brain. The proposed research will focus on the following short-term objectives: 1) Establish targets for investigating how acute exercise promotes domain-specific cognitive effects by manipulating the exercise-stress response and evaluating potential sex differences related to exercise-induced lactate effects. 2) Bridge the gap in acute-to-chronic exercise effects using a novel intervention model to determine how exercise-induced adaptations in neural plasticity change with training and whether those adaptions persist following detraining. 3) Combine exercise and cognitive training to identify how they interact to alter the human brain. Impact: This integrative and multidisciplinary research that tests the mechanistic underpinnings revealed in animal models is needed to advance the field. The findings will uncover novel areas of inquiry for researchers studying brain plasticity and inform the development of new intervention models for cognitive enhancement. Ultimately, this fundamental work will inform the creation of novel pharmaceuticals to prevent dementia, which will be transformative for people who cannot exercise vigorously.