Connections of the superior colliculus with the tegmentum and the cerebellum in the hedgehog tenrec.
Different tracer substances were injected into the superior colliculus (CoS) in order to study its afferents and efferents with the meso-rhombencephalic tegmentum, the precerebellar nuclei and the cerebellum in the Madagascan hedgehog tenrec. The overall pattern of tectal connectivity in tenrec was similar to that in other mammals, as, e.g. the efferents to the contralateral paramedian reticular formation. Similarly the origin of the cerebello-tectal projection in mainly the lateral portions of the tenrec's cerebellar nuclear complex corresponded to the findings in species with little binocular overlap. In comparison to other mammals, however, the tenrec showed a consistent projection to the ipsilateral inferior olivary nucleus, in addition to the classical contralateral tecto-olivary projection. The tenrec's CoS also appeared to receive an unusually prominent monoaminergic input particularly from the substantia nigra, pars compacta. There was a reciprocal tecto-parabigeminal projection, a distinct nuclear aggregation of parabigeminal neurons, however, was difficult to identify. The dorsal lemniscal nucleus did not show perikaryal labeling in contrast to the paralemniscal region. Similar to the cat but unlike the rat there were a few neurons in the nucleus of the central acoustic tract. Unlike the cat, but similar to the rat there was a distinct, predominantly ipsilateral projection to the magnocellular reticular field known to project spinalward.
Künzle
H
H
Institute of Anatomy, University of Munich, Germany. kuenzle@anat.med.uni-muenchen.de
D000818:Animals; D001931:Brain Mapping; D002531:Cerebellum / Q000502:physiology*; D006364:Hedgehogs / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D011149:Pons / Q000502:physiology; D012249:Rhombencephalon / Q000502:physiology; D013378:Substantia Nigra / Q000502:physiology; D013477:Superior Colliculi / Q000502:physiology*; D013681:Tegmentum Mesencephali / Q000502:physiology*