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

Bohlen, Martin O.; Warren, Susan; May, Paul J.

doi:10.1007/s00429-015-1039-2

Cited by 23 publications

(36 citation statements)

References 95 publications

(162 reference statements)

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“…The collicular projection is also likely to be separate from the projection to EWpg described here, as Moschovakis et al (1988) did not observe non-tectal axon collaterals for cMRF reticulotectal neurons. The projection to EWpg is probably also separate from the population of cMRF neurons sending axons to the medulla and spinal cord, as these reticulospinal and reticuloreticular neurons display a very different distribution within the cMRF (Warren et al 2008; Perkins et al 2009) than those reported to project to the SOA and EWpg (Bohlen et al 2015). Certainly, a connection between lens and pupil control and head turning would not be expected.…”

Section: Discussionmentioning

confidence: 97%

“…While neither the confocal nor the ultrastructural evidence is incontrovertible, the combined results from these two lines of evidence strongly support the contention that cells in the cMRF synaptically contact preganglionic motoneurons. Previous work has already shown that injections of retrograde tracers that include the EWpg along with the supraoculomotor area (SOA) and oculomotor nucleus (III) do label cells within the cMRF (Bohlen et al 2015). These cells occupy a horizontally oriented sublamina within the middle third of the cMRF.…”

Section: Discussionmentioning

confidence: 99%

“…In all cases, the aspiration defect was then filled with Gelfoam and the incision closed with suture. See Bohlen et al (2015) for further details.…”

Section: Methodsmentioning

confidence: 99%

“…Examination of these cases indicated that labeled terminals were present within the confines of the supraoculomotor area (SOA). A recent detailed examination of this SOA projection in a primate model (Bohlen et al 2015), noted that the cMRF might provide input to either the preganglionic component of the Edinger–Westphal nucleus (EWpg) or the centrally projecting component of the Edinger–Westphal nucleus (EWcp).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2015

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The central mesencephalic reticular formation, a region associated with horizontal gaze control, has recently been shown to project to the supraoculomotor area in primates. The Edinger–Westphal nucleus is found within the supraoculomotor area. It has two functionally and anatomically distinct divisions: (1) the preganglionic division, which contains motoneurons that control both the actions of the ciliary muscle, which focuses the lens, and the sphincter pupillae muscle, which constricts the iris, and (2) the centrally projecting division, which contains peptidergic neurons that play a role in food and fluid intake, and in stress responses. In this study, we used neuroanatomical tracers in conjunction with immunohistochemistry in Macaca fascicularis monkeys to examine whether either of these Edinger–Westphal divisions receives synaptic input from the central mesencephalic reticular formation. Anterogradely labeled reticular axons were observed making numerous boutonal associations with the cholinergic, preganglionic motoneurons of the Edinger–Westphal nucleus. These associations were confirmed to be synaptic contacts through the use of confocal and electron microscopic analysis. The latter indicated that these terminals generally contained pleomorphic vesicles and displayed symmetric, synaptic densities. Examination of urocortin-1-positive cells in the same cases revealed fewer examples of unambiguous synaptic relationships, suggesting the centrally projecting Edinger–Westphal nucleus is not the primary target of the projection from the central mesencephalic reticular formation. We conclude from these data that the central mesencephalic reticular formation must play a here-to-for unexpected role in control of the near triad (vergence, lens accommodation and pupillary constriction), which is used to examine objects in near space.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

“…In all cases, the aspiration defect was then filled with Gelfoam and the incision closed with suture. See Bohlen et al (2015) for further details.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2015

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“…[4][5][6] These reach the medial longitudinal fasciculus for downgaze and pretectal plate for upgaze. 7 Supranuclear paralysis of upgaze results from bilateral lesions of the pretectal area involving the fibers and nuclei of the posterior commissure. A single lesion of the posterior commissure, as seen in our patient, can at times result in upgaze paralysis due to the large decussation of fibers within the commissure.…”

Section: Oy-stersmentioning

confidence: 99%

Pearls & Oy-sters: Looking up the anatomy of looking up

et al. 2016

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PEARLS1. A unilaterally dilated pupil would indicate that the lesion is fascicular rather than nuclear as the Edinger-Westphal nucleus is in the midline and causes bilateral mydriasis. 2. The inferior rectus, medial rectus, and inferior oblique muscles are supplied ipsilaterally while the superior rectus is supplied contralaterally. A 46-year-old Chinese man with diabetes mellitus, hypertension, and hyperlipidemia, developed sudden onset of vertiginous dizziness and diplopia that was worse on looking up. His symptoms were not preceded by any antecedent infections, neither was there any headache. Blood pressure on arrival in the Emergency Department was 145/95 mm Hg and his neurologic examination revealed bilateral upward gaze restriction (video on the Neurology ® Web site at Neurology.org). There was voluntary lid retraction by the patient. The pupils were 3 mm bilaterally and reactive to light and accommodation, there was no ptosis or nystagmus, and no fatigability could be elicited. Apart from esophoria and pseudo-6th nerve palsy, the rest of the eye movements were normal. Other cranial nerves, motor, sensory, and cerebellar examinations were unremarkable. The vertical optokinetic reflex was intact and there was no tremor of the upper limbs. On forced eye closure, there was upward deviation of his eyes consistent with the Bell phenomenon. ECG did not show any atrial fibrillation or ischemic changes. The basic blood investigations were unremarkable. He was initially diagnosed with myasthenia gravis with frontalis overactivity and complex ophthalmoplegia by the admitting emergency physicians.MRI revealed a lesion in the anterior periaqueductal midbrain, eccentrically situated to the left of the midline. The apparent diffusion coefficient characteristics were in keeping with an acute infarct (figure 1, A and B) and magnetic resonance angiogram did not reveal any stenosis. The patient was treated with aspirin, statins, and tight blood pressure control. DISCUSSION In our patient, abduction, adduction, downgaze, and convergence were preserved, and there was no ptosis, indicating that the respective subnuclei were spared. Apart from esophoria and a pseudo-6th nerve palsy, the only findings were asymmetric upgaze restriction and lid retraction ( figure 2A and video). This can be explained by the infarct in the caudal midline region in the posterior commissure location (figures 1C and 2B), which provides regulation to the respective superior rectus subnucleus.A review of the spatial anatomy of the subnuclei components of the oculomotor complex and its surrounding structures would be useful in understanding this clinical presentation and that of other midbrain lesions. This can help in precise localization of the lesion in nuclear and perinuclear 3rd-nerve palsies 1 ( figure 1C).Presentation of supranuclear lesions. The oculomotor nuclear complex is situated in the midbrain at the level of the superior colliculus, ventral to the periaqueductal gray matter. It is composed of paired and unpaired subnuclei and lesions conf...

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A central mesencephalic reticular formation projection to medial rectus motoneurons supplying singly and multiply innervated extraocular muscle fibers

Bohlen

Warren

May

2017

J of Comparative Neurology

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We recently demonstrated a bilateral projection to the supraoculomotor area from the central mesencephalic reticular formation (cMRF), a region implicated in horizontal gaze changes. C-group motoneurons, which supply multiply innervated fibers in the medial rectus muscle, are located within the primate supraoculomotor area, but their inputs and function are poorly understood. Here, we tested whether C-group motoneurons in Macaca fascicularis monkeys receive a direct cMRF input by injecting this portion of the reticular formation with anterograde tracers in combination with injection of retrograde tracer into the medial rectus muscle. The results indicate that the cMRF provides a dense, bilateral projection to the region of the medial rectus C-group motoneurons. Numerous close associations between labeled terminals and each multiply innervated fiber motoneuron were present. Within the oculomotor nucleus, a much sparser ipsilateral projection onto some of the A- and B-group medial rectus motoneurons that supply singly innervated fibers was observed. Ultrastructural analysis demonstrated a direct synaptic linkage between anterogradely labeled reticular terminals and retrogradely labeled medial rectus motoneurons in all three groups. These findings reinforce the notion that the cMRF is a critical hub for oculomotility by proving that it contains premotor neurons supplying horizontal extraocular muscle motoneurons. The differences between the cMRF input patterns for C-group versus A- and B-group motoneurons suggest the C-group motoneurons serve a different oculomotor role than the others. The similar patterns of cMRF input to C-group motoneurons and preganglionic Edinger-Westphal motoneurons suggest that medial rectus C-group motoneurons may play a role in accommodation-related vergence.

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

Cited by 23 publications

References 95 publications

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

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

Pearls & Oy-sters: Looking up the anatomy of looking up

A central mesencephalic reticular formation projection to medial rectus motoneurons supplying singly and multiply innervated extraocular muscle fibers

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