On susceptibility weighted imaging sequences, this structure’s posterior portion normally resembles a swallow’s tail. On an axial view, this structure separates the red nucleus from the peduncle. This structure closely corresponds to the rodent A9 cell group. This structure both stimulates the direct pathway [emphasize] and inhibits the indirect pathway (15[1])through projections that synapse onto the medium spiny neurons of the dorsal (*) striatum. (10[1])MPTP destroys the cells in this structure’s (10[1])pars compacta responsible (10[1])for producing a molecule whose deficiency can cause cogwheel rigidity and a shuffling gait. (10[2])The characteristic (10[1])appearance of this portion of the basal ganglia (10[1])results from high levels of neuromelanin. For 10 points, the depletion of what structure’s dopaminergic neurons characterizes Parkinson’s disease, and causes it to lose its “black” appearance? (-5[1])■END■ (10[2]0[1])