Transneuronal retinal input to the primate Edinger-Westphal nucleus

Abstract

The Edinger-Westphal nucleus of the oculomotor nuclear complex provides preganglionic parasympathetic innervation to the pupil. We labelled its retinal input by transneuronal autoradiography after an eye injection of [3H]proline in the macaque monkey. The primary retinal projection to the pretectum terminated in the ipsilateral and contralateral olivary nuclei. These nuclei were intensely labelled and sharply delimited, with a mean diameter of 590 microm and a rostrocaudal length of 2.52 mm. The caudal half of the olivary nucleus on each side broke into multiple clumps of label. Fragments of label also surrounded each olivary nucleus. The exact pattern of pretectal labelling varied considerably among animals and even from side to side in the same animal. In 5 of 6 monkeys, label from the olivary nucleus reached the Edinger-Westphal nucleus transneuronally. In transverse sections, the Edinger-Westphal label appeared as a circular patch located on either side of the midbrain ventral to the cerebral aqueduct in the central gray matter. It averaged 230 microm in diameter and 610 microm in length. In Nissl-stained sections, the autoradiographic label corresponded to a distinct nucleus comprised of neurons that were smaller than neurons in nearby somatic subdivisions of the oculomotor complex. The mean area of Edinger-Westphal neurons was 295 microm2. Transneuronal retinal input to the Edinger-Westphal nucleus mediating pupillary constriction terminates in a single, well-defined cell group in the midbrain.

Defining the pupillary component of the perioculomotor preganglionic population within a unitary primate Edinger–Westphal nucleus

“…Trans-synaptic tracer experiments suggested that this nucleus receives retinal input by way of the pretectum (Kourouyan and Horton, 1997). The present study indicates the lvc is not part of EW PG , but is instead a satellite nucleus that receives bilateral pretectal input and projects back upon the contralateral pretectum, by way of the posterior commissure.…”

“…4C-G). We believe this structure is equivalent to the one termed the lateral visceral column (lvc) in previous studies (Kourouyan and Horton, 1997;Baleydier et al, 1990;Büttner-Ennever et al, 1996), and so have continued to use this term to identify it. The lvc appears to be connected to the contralateral pretectum by way of the posterior commissure (Fig.…”

“…The present study indicates the lvc is not part of EW PG , but is instead a satellite nucleus that receives bilateral pretectal input and projects back upon the contralateral pretectum, by way of the posterior commissure. Based on the findings of Kourouyan and Horton (1997), it must be supplied with visual sensory input from either the OPt or the nOT. The function of this cell group is unknown.…”

“…These subdivisions took on added importance when trans-synaptic anterograde tracers were utilized in an attempt to define the pupillary light reflex pathway in the monkey (Kourouyan and Horton, 1997). This study indicated that the lateral visceral column (lvc) represents the portion of EW that receives input from the retina, by way of the olivary pretectal nucleus (OPt).…”

Visual Pathway for the Optokinetic Reflex in Infant Macaque Monkeys

“…Lesion studies in primates demonstrate the relevance of striate and extrastriate visual cortical areas for unperturbed slow eye movements and symmetric mhOKN (e.g., Ter Braak and Van Vliet, 1963;Lynch and McLaren, 1983;Zee et al, 1987;Dürsteler and Wurtz, 1988). As we failed to reveal a cortical input to the NOT-DTN at P9, binocularity in the NOT-DTN up to this age should indeed originate from the direct projections of retinal ganglion cells from both eyes (Ballas et al, 1981;Kourouyan and Horton, 1997;Telkes et al, 2000). However, already at P12 and P14, we could convincingly demonstrate a direct cortical projection to the NOT-DTN arising from V1 and even more strongly from MT which, however, did not increase binocular balance at once, i.e., a large proportion of neurons was still dominated by the contralateral eye.…”