Changes in Cortical Activity in the OBiden Model of Multiple Sclerosis

Science Center A255

Multiple Sclerosis (MS) is a demyelinating disease and one of the most common disorders of the central nervous system, affecting 2.5 million patients worldwide. Despite its prevalence, however, the etiology of this disease is not well characterized. Recent work in the Gow laboratory has led to the development of a novel model of white matter pathology for MS, the OBiden mouse. Behavioral testing has demonstrated that OBiden mice exhibit a depression-like endophenotype at 6 and 12 months of age, and develop deficits in learning and memory by 12 months. To investigate the neurophysiological correlates of these behavioral changes, subdermal EEGs were measured to determine changes in interhemispheric coherence, which is an indication of functional association between brain regions (Thatcher et al., 2004). Previous work on 12 month OBiden mice revealed a decrease in theta band coherence compared to healthy controls. Clinically, EEG coherence from MS patients is also reported to be decreased in the theta band, suggesting parallels in the pathophysiology between OBiden mice and MS patients. Theta band coherence is poorly understood, but is thought to be associated with cognition and memory (Leocani et al., 2001). In view of the EEG pathology we observed at 12 months, my work this summer focused on characterizing 6 month OBiden mice which, in contrast to those at 12 months, have normal EEGs. These data indicate that altered interhemispheric coherence is an emergent phenotype associated with disease progression in OBiden mice, beginning between 6 and 12 months of age.