Is there a primitive reflex residue underlying Marcus Gunn Syndrome? Rat electrophysiology

Ying Qiao; Hou-Cheng Liang; Jing-Dong Zhang; Pi-Fu Luo; An-Le Su; Ting Zhang; Hong-Na Zhu

doi:10.18240/ijo.2020.01.05

International Journal of Ophthalmology (Jan 2020)

Is there a primitive reflex residue underlying Marcus Gunn Syndrome? Rat electrophysiology

Ying Qiao,
Hou-Cheng Liang,
Jing-Dong Zhang,
Pi-Fu Luo,
An-Le Su,
Ting Zhang,
Hong-Na Zhu

Affiliations

Ying Qiao: Xi’an First Hospital, Key Clinic Ophthalmology Lab, Shaanxi Province Eye Research Institute, Xi’an 710002, Shaanxi Province, China
Hou-Cheng Liang: Xi’an First Hospital, Key Clinic Ophthalmology Lab, Shaanxi Province Eye Research Institute, Xi’an 710002, Shaanxi Province, China; Xi’an BRIGHT Eye Hospital, 234 West Youyi Road, Xi’an 710068, Shaanxi Province, China; Department of Ophthalmology, Affiliated Hospital, Xi’an Jiaotong University, Xi’an 710002, Shaanxi Province, China
Jing-Dong Zhang: Xi’an First Hospital, Key Clinic Ophthalmology Lab, Shaanxi Province Eye Research Institute, Xi’an 710002, Shaanxi Province, China; Xi’an BRIGHT Eye Hospital, 234 West Youyi Road, Xi’an 710068, Shaanxi Province, China
Pi-Fu Luo: Department of Pathology, University of Iowa College of Medicine, Iowa City, IA 52242, USA
An-Le Su: Xi’an First Hospital, Key Clinic Ophthalmology Lab, Shaanxi Province Eye Research Institute, Xi’an 710002, Shaanxi Province, China
Ting Zhang: Xi’an First Hospital, Key Clinic Ophthalmology Lab, Shaanxi Province Eye Research Institute, Xi’an 710002, Shaanxi Province, China
Hong-Na Zhu: Xi’an First Hospital, Key Clinic Ophthalmology Lab, Shaanxi Province Eye Research Institute, Xi’an 710002, Shaanxi Province, China

DOI: https://doi.org/10.18240/ijo.2020.01.05
Journal volume & issue: Vol. 13, no. 1
pp. 29 – 35

Abstract

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AIM: To make an electrophysiological demonstration of a possible jaw muscle afferents-oculomotor neural pathway that was proposed by our previous works on rats, which substantiates an early “release hypothesis” on pathogenesis of human Marcus Gunn Syndrome (MGS). METHODS: Extracellular unit discharge recording was applied and both orthodromic and spontaneous unitary firing were recorded in the oculomotor nucleus (III), and the complex of pre-oculomotor interstitial nucleus of Cajal and Darkschewitsch nucleus (INC/DN), following electric stimulation of the ipsilateral masseter nerve (MN) in rats. RESULTS: Extracellular orthodromic unit discharges, with latencies of 3.7±1.3 and 4.7±2.9ms, were recorded unilaterally in the III, and the INC/DN neurons, respectively. Spontaneous unit discharges were also recorded mostly in the INC/DN and less frequently in the III. Train stimulation could prompt either facilitation or inhibition on those spontaneous unit discharges. The inhibition pattern of train stimulation on the spontaneous discharging was rather different in the III and INC/DN. A slow inhibitory pattern in which spontaneous firing rate decreased further and further following repeated train stimulation was observed in the III. While, some high spontaneous firing rate units, responding promptly to the train stimuli with a short-term inhibition and recovered quickly when stimuli are off, were recorded in the INC/DN. However, orthodromic unit discharge was not recorded in the III and INC/DN in a considerable number of experiment animals. CONCLUSION: A residual neuronal circuit might exist in mammals for the primitive jaw-eyelid reflex observed in amphibians, which might not be well-developed in all experimental mammals in current study. Nonetheless, this pathway can be still considered as a neuroanatomic substrate for development of MGS in some cases among all MGS with different kind of etiology.

Published in International Journal of Ophthalmology

ISSN: 2222-3959 (Print); 2227-4898 (Online)
Publisher: Press of International Journal of Ophthalmology (IJO PRESS)
Country of publisher: China
LCC subjects: Medicine: Ophthalmology
Website: http://www.ijo.cn/gjyken/ch/index.aspx

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