Neurochemical significance of the red nucleus.

This study reviews some of the more prominent reports related to neuromelanin and the physiological significance of the substantia nigra and the red nucleus. The phylogenetic and ontogenetic parallelism between these two structures is considered. The presence of dopachrome in the red nucleus and of neuromelanin in the substantia nigra is discussed. An experimental study in four human brains in which the red nucleus was injected with zinc sulfate showed the presence of neuromelanin in the red nucleus. This is the first reported demonstration that dopachrome present in the red nucleus is the precursor of neuromelanin.