Functional MRI: to better understand the role of cortical plasticity in multiple sclerosis
MRI is an essential tool when diagnosing multiple sclerosis (MS), required to show dissemination of lesions in space and time. The known discrepancy between lesion load and the clinical state of the patients, as reflected in their disability or lack thereof, is designated the "clinico-radiological paradox. Cases where the lesions load is relatively robust, but the patients have mild evidence of clinical disability, suggest that mechanisms other than demyelination, remyelination, and axonal loss play a compensatory part.
The possibility of cortical plasticity, the brain's ability to adapt to damage, in MS is much debated. Since we are considering an adult brain, we do not expect the brain to rewire itself following the insult. However, reinforcement of existing functional networks or redistribution of the relative weight of certain regions in the network may play a role in the recovery process.
In my talk, I will review studies that try to better define plasticity mechanisms by using functional MRI (fMRI), a specialized imaging technique measuring the hemodynamic response related to neural activity in the brain. Special attention will be given to compensatory mechanism to overcome visual damage following optic neuritis.
I will present studies that suggest that adaptive cortical plasticity involve higher visual areas to overcome the visual insult; other studies that emphasize compensatory mechanism within the temporal domain designed to synchronize input arriving at the primary visual cortex from the two eyes; and finally studies that evaluate the visual system in a holistic manner through the visual functional networks.