Search results for "oculomotor"
showing 10 items of 38 documents
Ocular pseudomyasthenia: report of a case with a pineal region tumor.
1991
A case presenting with clinical features of ocular myasthenia and a false-positive edrophonium test is reported. Brain CT and MRI scan revealed a pineal region tumor histologically verified as germinoma. We recommend evaluating patients with clinical features of myasthenia gravis (MG) confined to the ocular muscles for intracranial mass lesions.
Senataxin defective in ataxia oculomotor apraxia type 2 is involved in the defence against oxidative DNA damage
2007
Adefective response to DNA damage is observed in several human autosomal recessive ataxias with oculomotor apraxia, including ataxia-telangiectasia. We report that senataxin, defective in ataxia oculomotor apraxia (AOA) type 2, is a nuclear protein involved in the DNA damage response. AOA2 cells are sensitive to H2O2, camptothecin, and mitomycin C, but not to ionizing radiation, and sensitivity was rescued with full-length SETX cDNA. AOA2 cells exhibited constitutive oxidative DNA damage and enhanced chromosomal instability in response to H2O2. Rejoining of H2O2-induced DNA double-strand breaks (DSBs) was significantly reduced in AOA2 cells compared to controls, and there was no evidence fo…
Cerebellar learning of bio-mechanical functions of extra-ocular muscles: modeling by artificial neural networks
2003
A control circuit is proposed to model the command of saccadic eye movements. Its wiring is deduced from a mathematical constraint, i.e. the necessity, for motor orders processing, to compute an approximate inverse function of the bio-mechanical function of the moving plant, here the bio-mechanics of the eye. This wiring is comparable to the anatomy of the cerebellar pathways. A predicting element, necessary for inversion and thus for movement accuracy, is modeled by an artificial neural network whose structure, deduced from physical constraints expressing the mechanics of the eye, is similar to the cell connectivity of the cerebellar cortex. Its functioning is set by supervised reinforceme…
The role of the claustrum in the bilateral control of frontal oculomotor neurons in the cat.
1991
The effect of claustrum (CL) stimulation on the spontaneous unitary activity of ipsi and contralateral frontal oculomotor neurons, was studied in chloralose-anaesthetized cats. A total of 205 units was bilaterally recorded in the medial oculomotor area, homologous of the primate "frontal eye fields"; 127 neurons were identified as projecting to the superior colliculus; for 33 of these last units stimulation of the ipsilateral CL provoked an excitatory effect lasting 10-25 ms and appearing with a latency of 5-15 ms; on 8 units the excitatory effect was followed by an inhibition lasting 100-250 ms. Ninety-eight of the 127 neurons were also tested through activation of the contralateral CL: 13…
SOMATOTOPIC ORGANIZATION OF THE CRANIAL NERVE NUCLEI INVOLVED IN EYE MOVEMENTS: III, IV, VI.
2017
The oculomotor nucleus is divided into: 1. somatic medial column innervating the superior rectus muscle and somatic lateral column, further subdivided into a lateral column innervating the inferior rectus, inferior oblique and medial rectus muscles; 2. central nucleus innervating the levator palpebrae superioris muscle; 3. visceral nucleus innervating the pupillary sphincter muscle, consisting of the following two groups of neurons: cholinergic, preganglionic neurons supplying the ciliary ganglion, termed the Edinger- Westphal preganglionic (EWpg) neuron population, and the centrally projecting, peptidergic neurons, termed the Edinger-Westphal centrally projecting (EWcp) population. A detai…
Vascular Third Nerve Compression—A Possible Cause of Episodic Vertical Diplopia?
2006
We report a 74-year-old man with a 2-year history of episodes of vertical diplopia. In the beginning, there was one episode every 2–3 months, which increased over time to an average of one episode every 2 weeks. These complaints were attributed to an MRI-documented vascular third nerve compression. Treatment with gabapentin (400 mg q.i.d.) was followed by cessation of episodic diplopia.
Effect of claustrum stimulation on neurons of the contralateral medial oculomotor area, in the cat
1990
In chloralose-anaesthetized cats, the extracellular spontaneous unitary activity was recorded from 157 neurons, located in the medial oculomotor area. 98 units were identified as projecting onto the superior colliculus. Electrical stimulations of the contralateral claustrum provoked, on 13 of these cells, an excitatory effect, lasting 10-35 ms and appearing with a latency of 20-50 ms. Full length section of the corpus callosum totally abolished the contralateral claustrum effect. The results suggest that in the cat, the claustrum may have a role in the bilateral control of the visuo-motor performance.
Response of abducens internuclear neurons to axotomy in the adult cat
2000
The highly specific projection of abducens internuclear neurons on the medial rectus motoneurons of the oculomotor nucleus constitutes an optimal model for investigating the effects of axotomy in the central nervous system. We have analyzed the morphological changes induced by this lesion on both the cell bodies and the transected axons of abducens internuclear neurons in the adult cat. Axotomy was performed by the transection of the medial longitudinal fascicle. Cell counts of Nissl-stained material and calretinin-immunostained abducens internuclear neurons revealed no cell death by 3 months postaxotomy. Ultrastructural examination of these cells at 6, 14, 24, and 90 days postaxotomy showe…
Binocular motility system and temporomandibular joint internal derangement: A study in adults
2007
Abstract INTRODUCTION: Ocular convergence defects have been confirmed in adults with temporomandibular joint (TMJ) dysfunction, but few studies of the relationship of the oculomotor apparatus to TMJ disc displacement have been reported. The purpose of this study was to examine the impact of disc displacement on the oculomotor capacity of the eyes in adults. METHODS: Fifty symptomatic patients with bilateral TMJ disc displacement (13 men, 37 women; mean age, 28.84 +/- 8.22 years; range, 18-40 years) were compared with the same number of asymptomatic volunteers with normal disc position (14 men, 36 women; mean age, 29.96 +/- 5.04 years; range, 18-37 years). All subjects underwent standardized…
A Pathway in the Brainstem for Roll-Tilt of the Subjective Visual Vertical: Evidence from a Lesion–Behavior Mapping Study
2012
The perceived subjective visual vertical (SVV) is an important sign of a vestibular otolith tone imbalance in the roll plane. Previous studies suggested that unilateral pontomedullary brainstem lesions cause ipsiversive roll-tilt of SVV, whereas pontomesencephalic lesions cause contraversive roll-tilts of SVV. However, previous data were of limited quality and lacked a statistical approach. We therefore tested roll-tilt of the SVV in 79 human patients with acute unilateral brainstem lesions due to stroke by applying modern statistical lesion–behavior mapping analysis. Roll-tilt of the SVV was verified to be a brainstem sign, and for the first time it was confirmed statistically that lesions…