The Effects of a Dual Motor-Cognition Task on Cognitive Overload in Individuals with Multiple Sclerosis: An fNIRs Study

Multiple Sclerosis (MS), a central nervous system disease, is characterized by cognitive and motor difficulties. In particular, during multitasking, individuals with MS have been shown to have greater activation within the prefrontal cortex (PFC) due to increase in energy demands in order to compensate for the increasing difficulty of a task. As a result, there is a greater blood flow of oxygen and nutrients to regions of the brain that are related to executive function and working memory involved in multitasking. However, negative concomitant effects related to walking, like fall risk are often the result of cognitive overload in individuals with MS due to declining cognitive and motor functioning. These effects are thought to be related to overload demands and reduced executive function. Functional Near-Infrared Neuroimaging (fNIRs) will indirectly measure brain activity within the PFC of individuals with MS performing various cognitive-motor tasks. The hemodynamic data will be used to explore hypotheses related to cognitive load, difficulty of task, and cognitive deficits within the PFC of individuals with MS. This research predicts that individuals with MS who are not cognitively impaired, but have declining cognitive functioning, will have increase activation in the dorsolateral prefrontal cortex (DLPFC) and decrease activation in the orbitofrontal prefrontal cortex (OFPFC) with increasing difficulty of task. Also, it is predicted that individuals with MS who are cognitively impaired will compensate by recruiting other regions adjacent to the DLPFC, such as other regions within the PFC, and therefore show reduced activity in the DLPFC. Also, this research hypothesizes that poor motor performance is positively correlated to a decrease in activation in the DLPFC, and an increase in fear of falling score is positively correlated to decrease DLPFC activation. Furthermore, these results may determine the clinical potential of fNIRs, such as by determining specific characteristics and patterns of brain activation in individuals with MS during multitasking that could be used for the diagnosis of MS, to track progress during an intervention, and to lower fall risk in everyday life