Mapping of the habenulo-interpeduncular pathway in living mice using manganese-enhanced 3D MRI

This magnetic resonance imaging (MRI) study describes mapping of the habenulo-interpeduncular pathway in living mice based on manganese-induced contrast. Six hours after intracerebroventricular microinjection of MnCl2, T1-weighted 3D MRI (2.35 T) at 117 μm isotropic resolution revealed a continuous pattern of anterograde labeling from the habenula via the fasciculus retroflexus to the interpeduncular nucleus. Alternatively, the less invasive systemic administration of MnCl2 allowed for monitoring of the dynamic uptake pattern of respective neural components with even higher reproducibility across animals. Time courses covered the range from 42 min to 24 h after injection. In conclusion, manganese-enhanced MRI may open new ways for functional assessments of the habenulo-interpeduncular system in animal models with cognitive impairment.