Distribution of thalamo-caudate neurons in the cat as demonstrated by horseradish peroxidase.

Distribution of thalamocaudate neurons in the cat was examined by means of the horseradish peroxidase (HRP) method. After injection of HRP into the head of the caudate nucleus (Cd), thalamic neurons labeled with HRP were observed mainly in the rhomboid nucleus (Rh), central medial nucleus (Ce), centre médian-parafascicular complex (CM-Pf) as well as in the midline and intralaminar regions surrounding the mediodorsal nucleus (MD). Distribution of HRP-labeled neurons in the centrolateral nucleus (CL) were localized in the medial parts of the nucleus. Many HRP-labeled neurons were also seen in the substantia nigra (SN) and retrorubral nucleus (Rr). Additionally, HRP-labeled neurons were found in the ventrolateral portions of the anteromedial nucleus (AM), lateral portions of the MD, ventral tegmental area of Tsai (vT) and the midline raphe nuclei, such as the rostral lineal (rL), central lineal (cL) and dorsal raphe (dR) nuclei.