PRETECTOFUGAL FIBERS FROM THE NUCLEUS OF THE OPTIC TRACT IN MONKEYS

KATO I WATANABE S SATO S NORITA M

I. Kato et al., PRETECTOFUGAL FIBERS FROM THE NUCLEUS OF THE OPTIC TRACT IN MONKEYS, Brain research, 705(1-2), 1995, pp. 109-117

66

INGLESE

Article

Neurosciences

Brain research → ACNP

0006-8993

705

1-2

1995

109 - 117

ISI

0006-8993(1995)705:1-2<109:PFFTNO>2.0.ZU;2-8

The nucleus of the optic tract (NOT) is the visuo-motor relay between the retina and preoculomotor structures in the pathway mediating optok inetic nystagmus (OKN). NOT lesions in monkeys produce no OKN toward t he lesioned side. Then, efferent fibers from the NOT course through th e brainstem and may reach the vestibular nucleus, which is proposed to be the final nucleus to the motor nucleus. In the present study, the tracer was injected through a micropipette in the NOT in four monkeys. Labeled terminals were observed ipsilaterally in the parabigeminal nu cleus, superficial layers of the superior colliculus, dorsal and later al terminal nuclei of the accessory optic system and pretectal nuclei and contralaterally in the NOT and superficial layers of the superior colliculus. Descending fibers from the NOT consisted of two major path ways: (1) fibers descended medially from the injection site through th e reticularis pontis oralis to reach the lateral part of the ipsilater al nucleus reticularis tegmenti pontis; (2) fibers projecting into the dorsal cap of inferior olive, by far the greatest number of labeled f ibers, descended ventrally along the lateral border of the reticularis pontis oralis and reached the medial lemniscus where they descended f urther and branched into the dorsolateral pontine nucleus, the lateral part of the nucleus reticularis tegmenti pontis, the peduncular ponti ne nucleus, the lateral pontine nucleus, the nucleus prepositus hypogl ossi, the medial vestibular nucleus and finally the dorsal cap of the inferior olive. Consistent with the physiological data, the direct ter minals to the medial vestibular nucleus could serve to drive the stora ge mechanisms and to produce OKN in the monkey.