Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Neuroscience

Supervisor

Heath, Matthew

Abstract

A growing body of literature has demonstrated that a single bout of aerobic exercise and/or hypercapnic manipulations increase cerebral blood flow (CBF) and are linked to a transient (i.e.,min) post-intervention executive function (EF) benefit. However, there are no direct studies examining whether a transient decrease in CBF elicits a post-intervention EF decrement. Accordingly, my thesis employed 10-min single bout manipulations of -30 mmHg and -50 mmHg lower-body negative pressure (LBNP) to determine whether a transient reduction in CBF impacts EF. LBNP was applied as it renders sub-atmospheric pressure to the lower limbs and redistributes blood from the upper to lower compartments of the body. Results demonstrated that a reduction in CBF at both LBNP magnitudes; however, this did not result in a post-intervention EF decrement. Accordingly my thesis demonstrates that an acute reduction in CBF does not negatively influence EF.

Summary for Lay Audience

Executive function is a component of cognition and supports our ability to plan and implement actions essential to activities of daily living (e.g., making a pot of coffee). A single bout of aerobic or resistance exercise for as little as 10-min benefits executive function. One candidate mechanism for this benefit is an exercise-mediated increase in blood flow to the brain (i.e., cerebral blood flow). Although there is some evidence demonstrating that an increase in cerebral blood flow in healthy young adults is linked to an executive function benefit, it is unclear whether a brief reduction in cerebral blood imparts a post-intervention executive function impairment. The goal of my thesis was to address this issue via the use of a technique known as lower body negative pressure (LBNP). LBNP utilizes vacuum pressure (or negative pressure) applied to the lower limbs and results in an accumulation of blood in the lower extremities and thus reduces blood flow other regions of the body; that is, LBNP provides a safe and reliable means to decrease cerebral blood flow. The results from my study demonstrated that blood flow to the brain decreased during LBNP; however, this change did not impact a post-intervention assessment of executive function. Accordingly, my results suggest that a brief (i.e., 10-min) reduction in brain blood flow does not result in post-intervention executive function impairment.

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