EFFERENT PROJECTIONS OF SUPERIOR COLLICULUS TO DIENCEPHALIC AND BRAINSTEM NUCLEI IN THE CAT——AN ANTEROGRADE HRP STUDY / 解剖学报

ABSTRACT

Ascending and descending efferent projections of superior coUiculus were indentified by means of the anterograde horseradish peroxidase technique in the cat.Following injections of HRP into the rostral superior colliculus, a large number of labeled terminals were found mainly in several of the ipsilateral thalamic nucleiventromedial division of the ventral nucleus of the lateral geniculate body, zona incerta,lateral posterior nucleus, parafasciculus nucleus and centromedian nucleus. The mediodorsal nucleus and thalamic reticular nucleus were also found mildly labeled.Labeling were most heavily concentrated in the ipsilateral dorsolateral division of pontine nucleus and caudal region of parabigeminal nucleus. The dorsal part of medial accessory olivary was the only nucleus labeled contralaterally. After injecting HRP into the caudal superior colliculus, only the dorsolateral division of pontine nucleus was densely labeled, while labeled terminals of caudal parabigeminal nucleus signifcantly reduced in amount. No labeled terminals were found in the thalamus as well as medial accessory olivary nucleus. These results indicate that the efferent connections of superior colliculus are topographically organized.