Axonal branches of the same cerebellar neurons terminate bilaterally in the thalamus

The efferent projections of the deep cerebellar nuclei which terminate bilaterally in the thalamus were investigated in the rat by means of the retrograde fluorescent double-labeling technique. After injection of True Blue or Fast Blue in the thalamus on one side and Nuclear Yellow on the other, the deep cerebellar nuclei on both sides contained many cells single-labeled from the contralateral thalamic injection and some cells double-labeled from both thalamic injections. Double-labeled cells were more numerous in the caudal part of the medial nucleus than in the other cerebellar nuclei. The present results indicate that some cerebellar cells give origin to bilateral thalamic projections by means of axon collaterals.