PROJECTION OF THE PARABIGEMINAL NUCLEUS ONTO THE SUPERIOR COLLICULUS IN THE RAT——A HORSERADISH PEROXIDASE(HRP)STUDY / 解剖学报

ABSTRACT

It is demonstrated that the parabigeminal nucleus of the rat is subdivided intodorsal,middle and ventral groups.The parabigeminal nucleus sends fibers to bila-teral superior colliculus,the rostral half of it predominantly projects to the rostralhalf of the contralateral superior colliculus,but the rostral end projects only to thecontralateral one;the caudal half of this nucleus predominantly projects to thecaudal half of the ipsilateral superior colliculus,but the caudal end projects only tothe ipsilateral one.The superficial layer of the superior colliculus receives projec-tions from the ipsilateral dorsal and ventral groups and from the contralateralmiddle group of the parabigeminal nucleus.The middle and deep layers receive pro-jections from the ipsilateral middle group and contralateral dorsal and ventral groups,and probably from the other groups of both sides.The superior colliculus also sends fibers to both parabigeminal nuclei,predo-minantly the ipsilateral side.The lateral tegmental area sends fibers to the middle and deep layers of the su-perior colliculus.From the results described above,it could be concluded that the parabigeminalnucleus——tectum——parabigeminal nucleus connections are not only concerned withsuperficial layer,but also with the middle and deep layers of the superior colliculus.The tegmentum——tectum——tegmentum connections are only concerned with the mid-dle and deep layers of the superior colliculus.