Temporal and spatial features of interhemispheric information transfer in multiple sclerosis: a multimodal approach of TMS-EEG coregistration, MRI and motor learning

Project funded by the Italian Multiple Sclerosis Foundation (FISM 2016/R/2).

Demyelination occurring in multiple sclerosis (MS) causes deficits in the conducting properties of axons, altering electrical signaling in the central nervous system. The corpus callosum (CC) is commonly affected in MS, and therefore the study of interhemispheric information transfer through callosal fibers is of great interest in MS research. Magnetic Resonance (MRI) and diffusor tensor (DTI) imaging studies demonstrated that MS show CC functional connectivity alterations that influence motor sequence learning. Transcranial magnetic stimulation (TMS) and electroencephalography (EEG) coregistration can trace interhemispheric connections with higher temporal resolution, and therefore could uncover an altered interhemispheric transfer time at early stages of the disease, even in absence of lesions and clinical disability. Aim of this project is to better understand the anatomo-physiological alterations of the CC in MS and their association with functional impairments. To investigate the mechanisms leading to alterations of interhemispheric transfer of cognitive and sensorimotor information we will employ a multimodal approach. By means of TMS-EEG coregistration and MRI we will derive fine measures of structural and effective connectivity related to different CC regions and to different fiber dimensions. Then, we will use a motor learning paradigm requiring interhemispheric information transfer to evaluate specific functional deficits.