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

Abstract

The primate Edinger-Westphal nucleus (EW) contains perioculomotor preganglionic (pIII PG ) motoneurons that control the lens and pupil. Separate subdivisions have been described in EW and termed visceral columns, with the lateral visceral column (lvc) reportedly receiving pretectal inputs for the pupillary light reflex. However, choline acetyl transferase staining reveals a single paired column of cells dorsal to the oculomotor nucleus, suggesting the EW is not subdivided. We investigated this issue by transneuronal retrograde labeling of pIII PG neurons in three monkey species. In all three, pIII PG neurons were contained in a single column. We have also examined which part of the macaque pIII PG population receives pretectal input. Injections of biocytin into the pretectum anterogradely labeled terminals that lay in close association with pIII PG motoneurons retrogradely labeled by ciliary ganglion injections of WGA-HRP. These close associations were concentrated in the ventromedial portion of the middle third of EW , suggesting this pIII PG region mediates pupillary control. In other cases, pretectal WGA-HRP injections, in addition to labeling terminals in the EW, produced a circular field of labeled neurons and terminals in the periaqueductal gray, dorsolateral to EW. This region may represent the previously designated lvc, but it does not contain pIII PG motoneurons.

Adolescent Intermittent ethanol exposure enhances ethanol activation of the nucleus accumbens while blunting the prefrontal cortex responses in adult rat

“…Our findings in ethanol-naïve adult Wistar rats are largely consistent with previous studies using various ethanol challenges of rats and mice (Ryabinin et al, 1999; Horn et al, 2008; May et al, 2008; Vilpoux et al, 2009) including ethanol dose-response curves as reported here (Ryabinin et al, 1997; Knapp et al, 2001). We report here that AIE results in a marked loss of the adult frontal cortical neuronal responses to ethanol challenge, a modest right shift in CeA and BLA dose responses and a significant increase in nucleus accumbens maximal responses at high ethanol doses.…”

A central mesencephalic reticular formation projection to the Edinger–Westphal nuclei

“…Due to the fact that saccades and attention have been closely correlated, one might posit that this projection was related to attentional changes in pupil diameter. However, in this study, we saw cMRF terminals spread throughout the rostrocaudal extent of the EWpg with close associations present on nearly all the motoneurons, not just the pupillary component of the EWpg, which is small, and topographically restricted (Warwick 1954; Erichsen and May 2002; May et al 2008b; Sun and May 2014a, b). This argues against a role for this cMRF projection in independent control of pupillary function, such as would be expected for attention, emotion or the pupillary light reflex.…”

“…EWpg contains cholinergic, preganglionic, parasympathetic motoneurons that project to the ciliary ganglion via the oculomotor nerve. They control lens accommodation and pupillary constriction via synapses with postganglionic motoneurons (Warwick 1954; Akert et al 1980; Burde and Loewy 1980; Clarke et al 1985; Crawford et al 1989; Loewenfeld 1993; Gamlin et al 1994; May et al 2008b; McDougal and Gamlin 2015). EWcp contains peptidergic neurons that project widely in the central nervous system.…”

A central mesencephalic reticular formation projection to the supraoculomotor area in macaque monkeys

“…This was due, in part, to the presence of species differences in their location and organization. However, direct comparison of the populations has led to a new terminology to describe them: the peptideric neurons have projections throughout the brain, and so are defined as Edinger-Westphal centrally projecting (EWcp) neurons, and the cholinergic motoneurons that supply the ciliary ganglion are defined as Edinger-Westphal preganglionic (EWpg) motoneurons (Horn et al 2008; Kozicz et al 2011; May et al 2008a; May et al 2008b). In monkeys, EWpg can be identified cytoarchitecturally as a nucleus lying dorsal to III (see figs 4A+F & 6A+E), but EWcp is more diffuse.…”