THE TOPOGRAPHICAL PROJECTION FROM THE VENTRAL LATERAL GENICULATE NUCLEUS TO THE SUPERIOR COLLICULUS AND PRETECTUM IN THE CAT / 解剖学报

The present investigation was performed on six adult cats. The morphology and distribution of the labeled cells in the ventral lateral geniculate nucleus (LGNv) were observed. Following the injection of horseradish peroxidase (HRP) into the deeper layers of the superior colliculus the labeled cells were found to concentrate ipsilaterally in the ventral part of the rostromedial division of the LGNv. The HRP-positive cells were composed of large-sized, smaller, round and oval ceils. In the cases of injection of HRP into the rostral pretectum, the HRP-positive cells were seen bilaterally in the caudolateral division of LGNv mainly in the contralateral part, while the labeled cells were found ipsilaterally in the ventral part of caudolateral division after injection of HRP into the caudal pretectum. These cells were smaller than that large ones of superior colliculus injection. The results indicate that the projection of the LGNv to the superior colliculus and pretectum is organized topographically.

TOPOGRAPHICAL PROJECTION BETWEEN THE PARABIGEMINAL NUCLEUS AND SUPERIOR COLLICULUS IN THE CAT——A RETROGRADE AND ANTEROGRADE STUDY WITH HRP / 解剖学报

The topographical projection between the parabigeminal nucleus and the superiorcolliculus in the cat was investigated by retrograde and anterograde HRP tracingtechnique.Following HRP injection in the rostral superior colliculus,the labeledsomata were found predominantly in the rostral region of contralateral parabigeminalnucleus,but labeled terminals were heavily distributed in the ipsilateral parabigeminalnucleus,mainly in the caudal region.Following injection of HRP into caudal superiorcolliculus,the labeled somata and terminals were seen in ipsilateral parabigeminalnucleus,chiefly in caudal part,but their number was significantly decreased.It wasnoted that the labeled somata were sparse but labeled terminals were not found inthe parabigeminal nucleus,when the injection was restricted to superficial layers ofsuperior colliculus.After HRP injection into deeper layers of superior colliculus,there existed not only the labeled somata but also the labeled terminals in theparabigeminal nucleus,the former was distributed in bilateral parabigeminal nucleus,the latter in ipsilateral nucleus,chiefly in the caudal part.These results show thatthere are topographical connections between the parabigeminal nucleus and superiorcolliculus,and the parental somata contributing axons to the parabigeminal nucleusare located in deeper layers of the ipsilateral superior colliculus.

SUBCORTICAL AFFERENT CONNECTIONS OF THE CENTRAL LATERAL NUCLEUS OF THALAMUS IN THE CAT / 解剖学报

The afferent connections and topographical organization of the central lateral nucleus were studied with HRP retrograde tracing technique in 10 adult cats. The central lateral nucleus received projections from the forebrain, brainstem and cerebellum. The nuclei, projected to the caudal region of the central lateral nucleus, included the dorsal division of the ventral lateral geniculate nucleus, the thalamic reticular nucleus and the deep layers of superior colliculus, primarily on the ipsilateral side. The intralaminar thalamic nucleus, the lateral hypothalamus and the reticular part of substantia nigra sent axons to terminate in the rostral region of the central lateral nucleus, with an ipsilateral predominance. The nuclei, projected to the whole length of the central lateral nucleus, were the vestibular neuclei, the reticular formation of brainstem, zona incerta, pretectal area, cells surrounding the occulomotor complex, principal sensory trigeminal, cuneatus, gracilis as well as cerebellar dentate. The vestibular nuclei and the reticular formation of brainstem were found bilateral projection, the former predominantly in contralateral, the latter mainly in ipsilateral part. Except the zona incerta, pretectal area and cells surrounding the occulomotor, the rest were labeled primarily on the contralateral side. If HRP was injected into the central lateral nucleus and spread to the ventral anterior nucleus of thalamus, a lot of HRP-positive cells were found in the entopeduncular nucleus, while the ventral tegmental nucleus of Gudden was filled with densely labeled terminals mainly on the ipsilateral side. These findings indicate that the central lateral nucleus of thalamus may be involved multiple sensory and motor functions.

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

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 nuclei:ventromedial 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.