The organization of thalamic neurons projecting to the premotor cortex and the caudate nucleus in the cat studied by a fluorescent retrograde double labeling technique.

Thalamic neurons projecting to both the head of the caudate nucleus and the premotor cortex in the cat were studied by the retrograde fluorescent double labeling technique. After injections of Evans blue into the caudate nucleus, and diamidino-phenylindol into the premotor cortex, a small number of double labeled neurons appeared in the ventral anterior, ventral lateral, anteromedial, rhomboid, central dorsal, central lateral, central medial, paracentral and parafascicular nuclei, in addition to numerous single-labeled neurons. This indicates that some neurons in the thalamic nuclei send bifurcating axons to both the head of the caudate nucleus and the premotor cortex. The caudatal projections of these thalamic neurons are organized in a topical manner.