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Pretectal projections to the oculomotor complex of the monkey and their role in eye movements
Author(s) -
BüttnerEnnever J.A.,
Cohen B.,
Horn A.K.E.,
Reisine H.
Publication year - 1996
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(19960304)366:2<348::aid-cne12>3.0.co;2-l
Subject(s) - pretectal area , optokinetic reflex , oculomotor nucleus , optic tract , neuroscience , anatomy , extraocular muscles , biology , nucleus , vergence (optics) , pupillary light reflex , eye movement , midbrain , central nervous system , optic nerve , pupil , physics , optics
The nucleus of the optic tract (NOT) is associated with the generation of optokinetic nystagmus (OKN), whereas the olivary pretectal nucleus (ol), which lies embedded in the primate NOT, is believed to be essential for the pupillary light reflex. In this anatomical study of the pretectum, projections from NOT and ol to structures around the oculomotor nucleus were traced in the monkey, to determine which cell groups they innervated. 1. 3 [H]‐leucine injections were placed into NOT and ol, and labelled terminals were observed just outside the classical oculomotor nucleus (nIII), in the ‘C‐group’ and midline cell clusters, both of which contain small motoneurons of the extraocular eye muscles. In addition, there were strong projections to the lateral visceral cell column of the Edinger‐Westphal complex (lvc), but not to the Edinger‐Westphal nucleus (EW) itself. All of these projections were mainly contralateral. 2. NOT efferents terminated over the ipsilateral medial accessory nucleus of Bechterew (nB), but not over the adjacent nucleus Darkschewitsch. 3. Injections of a retrograde tracer into the oculomotor complex showed that the pretectal afferents described above originated mainly from the dorsomedial part of NOT and from ol. 4. The use of a transsynaptic retrograde tracer, tetanus toxin fragment (BII b ), established the monosynaptic nature of the connection between dorsomedial NOT (contralaterally) and ol (bilaterally), to the small extraocular motoneurons outside classical nIII. The ‘C‐group’ motoneurons may play a role in vergence, and lvc in pupillary constriction and depth of focus. Our results imply that NOT and ol participate in the control of some aspects of the near‐response, which may be important in the generation of some components of OKN in primates. © 1996 Wiley‐Liss, Inc.