Evaluation of brain activity changes occurring in an animal model for multiple sclerosis: a functional Magnetic Resonance Imaging study

Multiple Sclerosis (MS) is a chronic inflammatory demyelination disease of the central nervous system. It is characterized by blood brain barrier leakage during exacerbation phases and impairment in remyelination processes which are both detected by means of magnetic resonance imaging (MRI). Despite this technique is mainly used as diagnostic morphological tool for active and quiescent lesions, functional NMR (fMRI) may be used in MS patients to investigate the functional reorganization of brain cortex observed to overcome brain lesions. fMRI observations are already available in humans, but deeper knowledge on its usefulness might be gained using reliable animals models. By means of fMRI we investigated the brain plasticity in a chronic model of MS, i.e. Experimental Autoimmune Encephalomyelitis (EAE) in the Dark Agouti (DA) rat strain. Serial fMRI with somatosensory stimulation [1] and acquisitions were performed before, 30 and 60 days after EAE induction (dpi). Briefly electrical stimulation was delivered to the left forepaw during acquisition of MR images sensitive to Blood-Volume. A single stimulation protocol was composed of 30 images under rest condition and 10 images acquired during stimulation. After appropriate image analysis, performed using the FSL software package [2], the brain region activated by the applied stimulus was determined. Prior to EAE induction, electrical stimulation resulted in a localized response in the contralateral sensory motor cortex. Thirty and 60dpi, the activated area was greatly increased covering large regions of both contra and ipsilateral somatosensory cortex and extending also to extra-cortical regions. Our results show that DA EAE reproduces a remarkable findings observed in MS patients, i.e. the functional reorganization of motor cortex. It remains to be investigated whether this effect could represent an innovative platform for testing new therapeutic approaches for MS. References [1] Van Camp N, et al., NMR in Biomedicine, 19 (10) 2006 [2] www.fmrib.ox.ac.uk/fsl/ The authors acknowledge to have been supported in part by a grant of the Fondazione Italiana Sclerosi Multipla (FISM).