Grant: Operating Grant

Multiple sclerosis (MS) is the most common neurological disease affecting young adults in Canada. People with MS can suffer problems with movement and cognitive abilities and may also experience fatigue. Techniques such as transcranial magnetic stimulation (TMS) and brain imaging are providing insight into changes in the brain that are brought about by MS. Evidence from a variety of sources suggests that the brain of a person with MS can become hyper-excitable. Brain regions that are not normally important for performing a movement or mental task become active, and systems that normally help control the brain by inhibiting activity can stop working. Are the inhibitory systems themselves damaged by the disease? Or could an increase in activity be a natural adaptive response of the brain that allows people to function better despite the presence of damage to the nervous system? We are proposing a series of studies to test the idea that suppression of the brain's inhibitory system may be beneficial for cognitive and motor functioning. We will use TMS to examine changes in the brains of people with MS and relate these to their ability to perform cognitive and motor tasks. We also hypothesize that having a hyperexcitable brain uses up a lot of energy and could be responsible for the fatigue that is commonly seen in MS. Therefore, we will test whether changes in the brain's inhibitory system predict the development of fatigue during performance of a task. We expect the results will help us understand better how the brain responds to disease, not only in MS but also in other neurological disorders. They may also point the way to new therapies to help people with MS achieve their highest possible level of functioning.