Using Manganese Enhanced Magnetic Resonance Imaging (MEMRI) to Assess Calcium Dependent Activity in Vestibular Pathways Following Linear Acceleration

Reliable methods for repetitive and longitudinal assessment of central vestibular pathway function in vivo are rather limited. Manganese-enhanced magnetic resonance imaging (MEMRI) has been used in various sensory systems to evaluate neuronal activity in central pathways, but MEMRI assessment of central vestibular pathways has been minimal. The present study addressed this gap in knowledge by assessing whether Mn2+ can be taken up in an activity-dependent manner through voltage-gated calcium channels in the vestibular nuclear complex (VNC) and the vestibulocerebellum (VeCb) of rats with and without mild linear acceleration stimulation. R1 maps were collected prior to, one day after, and two weeks after Mn2+ administration in stimulated and non-stimulated rats. Analysis of MRI R1 values showed that one day after Mn2+ administration the VNC and VeCb had significantly greater R1 values that returned to baseline levels after two weeks. Non-stimulated rats had greater R1 values than stimulated rats. Mid rostro-caudal sections of the VNC had greater R1 values than rostral and caudal VNC sections. R1 values also indicated that Mn2+ was differentially taken up across subdivisions of the VNC and VeCb. These results correlate well with expected patterns of neuronal activity after linear acceleration. MEMRI is a sensitive tool that may be used to evaluate activity patterns in central vestibular nuclei, proving useful for studying underlying mechanisms of central vestibular dysfunction.