Selective retrograde labeling with D-[3H]-aspartate in the monkey olivocerebellar projection.

The specificity of D-[3H]-aspartate as a retrograde marker was investigated following large injections of this tritiated amino acid in the monkey cerebellar cortex. Retrogradely labeled neurons were found exclusively in the inferior olive, a fact which is consistent with previous studies in the rat. These results show that D-[3H]-aspartate is a selective tracer that might also be useful to delineate excitatory pathways using glutamate and/or aspartate as neurotransmitter(s) in the monkey brain.