scholarly journals Ocular Convergence Deficits in Schizophrenia

2012 ◽  
Vol 3 ◽  
Author(s):  
Mark S. Bolding ◽  
Adrienne C. Lahti ◽  
Timothy J. Gawne ◽  
Kristine B. Hopkins ◽  
Demet Gurler ◽  
...  
Keyword(s):  
Ocular Convergence

Eye Position Signals in the Abducens and Oculomotor Nuclei of Monkeys During Ocular Convergence

1994 ◽  
Vol 4 (5) ◽  
pp. 401-408 ◽  
Author(s):  
W. Michael King ◽  
Wu Zhou ◽  
R. David Tomlinson ◽  
Kathleen M.V. McConville ◽  
William K. Page ◽  
...  
Keyword(s):  
Eye Position ◽  
Oculomotor Nuclei ◽  
Ocular Convergence

Abducens internuclear neurons carry an inappropriate signal for ocular convergence

1989 ◽  
Vol 62 (1) ◽  
pp. 70-81 ◽  
Author(s):  
P. D. Gamlin ◽  
J. W. Gnadt ◽  
L. E. Mays
Keyword(s):  
Eye Movements ◽  
Action Potentials ◽  
Vestibular Nuclei ◽  
Lateral Rectus ◽  
Medial Rectus ◽  
Medial Longitudinal Fasciculus ◽  
Unit Recording ◽  
Antidromic Activation ◽  
Prepositus Hypoglossi ◽  
Ocular Convergence

1. Single-unit recording studies in alert Rhesus monkeys characterized the vergence signal carried by abducens internuclear neurons. These cells were identified by antidromic activation and the collision of spontaneous with antidromic action potentials. The behavior of abducens internuclear neurons during vergence was compared with that of horizontal burst-tonic fibers in the medial longitudinal fasciculus (MLF) and to that of a large sample of unidentified abducens cells (presumably both motoneurons and internuclear neurons). 2. The results indicate that abducens internuclear neurons and lateral rectus motoneurons behave similarly during vergence eye movements: the majority of both groups of cells decrease their firing rate for convergence eye movements: a minority show no change for vergence. This finding is strongly supported by recordings of horizontal burst-tonic fibers in the MLF, the majority of which decrease their activity significantly for convergence eye movements. 3. These findings indicate that a net inappropriate vergence signal is sent to medial rectus motoneurons via the abducens internuclear pathway. Because medial rectus motoneurons increase their activity appropriately during symmetrical convergence, this inappropriate MLF signal must be overcome by a more potent direct vergence input. 4. Overall, both abducens internuclear neurons and lateral rectus motoneurons decrease their activity for convergence less than would be expected based on their conjugate gain. This implies that some degree of co-contraction of the lateral and medial rectus muscles occurs during convergence eye movements. 5. Some horizontal burst-tonic MLF fibers decrease their activity more for convergence than any recorded abducens neuron. These fibers may arise from cells in the nucleus prepositus hypoglossi or vestibular nuclei.

scholarly journals Judging distance from ocular convergence

1998 ◽  
Vol 38 (4) ◽  
pp. 493-498 ◽  
Author(s):  
Eli Brenner ◽  
Wim J.M. Van Damme
Keyword(s):  
Ocular Convergence

Missing Lateral Rectus Force and Absence of Medial Rectus Co-Contraction in Ocular Convergence

2002 ◽  
Vol 87 (5) ◽  
pp. 2421-2433 ◽  
Author(s):  
Joel M. Miller ◽  
Christopher J. Bockisch ◽  
Dmitri S. Pavlovski
Keyword(s):  
Muscle Force ◽  
Muscle Fibers ◽  
Lateral Rectus ◽  
Medial Rectus ◽  
Common Path ◽  
Force Transducers ◽  
Force Finding ◽  
Muscle Innervation ◽  
The Brain ◽  
Ocular Convergence

For a given position of the eye in the orbit, most abducens motoneurons (LRMNs) fire at higher rates in converged gaze than when convergence is relaxed, implying that lateral rectus (LR) muscle force will be higher for a given eye position in convergence. If medial rectus (MR) muscle force balances LR force, it too would be higher in convergence, that is, LRMN recording studies predict horizontal rectus co-contraction in convergence. Three trained rhesus monkeys with binocular eye coils and custom muscle force transducers (MFTs) on LR and MR of one eye alternately fixated near (approximately 7 cm) and far (200 cm) targets with vergence movements of 20–30°. Tonic muscle forces were also measured during conjugate fixation of far targets over a 30 × 30° field. MFT characteristics and effects on oculomotility were assessed. Contrary to predictions, we found small (<1 g) decreases in both LR and MR forces in convergence, for those gaze positions that were used in the brain stem recording studies. This missing LR forceparadox (higher LRMN firing rates in convergence but lower LR forces) suggests that motoneurons or muscle fibers contribute differently to oculorotary forces in converged and unconverged states, violating the final common path hypothesis. The absence of MR co-contraction is consistent with, and supports, the missing LR force finding. Resolution of the missing LR force paradox might involve nonlinear interactions among muscle fibers, mechanical specialization of muscle fibers and other articulations of the peripheral oculomotor apparatus, or extranuclear contributions to muscle innervation.

Extrastriate cortical neurons correlated with ocular convergence in the cat

1993 ◽  
Vol 17 (2) ◽  
pp. 141-158 ◽  
Author(s):  
Mineo Takagi ◽  
Haruo Toda ◽  
Takehiko Bando
Keyword(s):  
Cortical Neurons ◽  
Ocular Convergence

scholarly journals Size-distance perception based on ocular convergence angle in 3- to 5-year-old children

2010 ◽  
Vol 6 (6) ◽  
pp. 733-733
Author(s):  
A. Yonas ◽  
C. E. Granrud ◽  
J. Grittner
Keyword(s):  
Distance Perception ◽  
Convergence Angle ◽  
Ocular Convergence

scholarly journals Wall-eyed bilateral internuclear ophthalmoplegia (webino syndrome) and myelopathy in pyoderma gangrenosum

1990 ◽  
Vol 48 (4) ◽  
pp. 497-501 ◽  
Author(s):  
Marco Aurélio Lana ◽  
Paulo Roberto R. Moreira ◽  
Leonardo B. Neves
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Pyoderma Gangrenosum ◽  
Medial Longitudinal Fasciculus ◽  
Sensory Level ◽  
Internuclear Ophthalmoplegia ◽  
Central Nervous System Vasculitis ◽  
Exact Location ◽  
Vascular Occlusive Disease ◽  
Ocular Convergence

A 35-year-old female with pyoderma gangrenosum developed paraparesis with a sensory level at L1. Three months later she complained of diplopia and was found to have bilateral internuclear ophthalmoplegia with exotropia and no ocular convergence. The term Webino syndrome has been coined to design this set of neuro-opthalmologic findings. Although it was initially attributed to lesions affecting the medial longitudinal fasciculus and the medial rectus subnuclei of the oculomotor complex in the midbrain the exact location of the lesion is still disputed. In the present case both myelopathy and Webino syndrome were probably due to vascular occlusive disease resulting from central nervous system vasculitis occurring in concomitance to pyoderma gangrenosum.

Characteristics of near response cells projecting to the oculomotor nucleus

1992 ◽  
Vol 67 (4) ◽  
pp. 944-960 ◽  
Author(s):  
Y. Zhang ◽  
L. E. Mays ◽  
P. D. Gamlin
Keyword(s):  
Firing Rate ◽  
Accommodation Coefficient ◽  
Medial Rectus ◽  
Eye Position ◽  
Oculomotor Nucleus ◽  
Unique Role ◽  
Distant Target ◽  
Accommodation Coefficients ◽  
Partial Dissociation ◽  
Ocular Convergence

1. Previous work has shown neurons just dorsal and lateral to the oculomotor nucleus that increase their firing rate with increases in the angle of ocular convergence. It has been suggested that the output of these midbrain near response cells might provide the vergence command needed by the medial rectus motoneurons. However, lens accommodation ordinarily accompanies convergence, and a subsequent study showed that only about one-half of these midbrain near response cells carried a signal related exclusively to vergence. One hypothesis suggested by this finding is that this subgroup of neurons might have a unique role in providing a "pure" vergence signal to the medial rectus motoneurons. 2. In the present study extracellular recordings were made from midbrain near response cells in monkeys while eye position and lens accommodation were measured. The monkeys viewed targets through an optical system that allowed the accommodative and ocular vergence demands to be manipulated independently. This approach was used to produce a partial dissociation of accommodative and vergence responses, so that an accommodative and vergence coefficient could be determined for each cell, by the use of the following equation FR = R0 + kda x AR + kdv x CR where FR is the firing rate of the near response cell, R0 is the predicted firing rate for a distant target, kda is the (dissociated) accommodation coefficient, AR is the accommodative response, kdv is the (dissociated) vergence coefficient, and CR is the convergence response. 3. The vergence and accommodation coefficients were determined for a large number of midbrain near response cells, including a subset that could be antidromically activated from the medial rectus subdivisions of the oculomotor nucleus. Some near response neurons were found with signals related exclusively to convergence (i.e., kdv greater than 0 and kda = 0), whereas several others had signals related exclusively to lens accommodation (i.e., kda greater than 0 and kdv = 0). The majority of the near response cells had signals related to both responses (i.e., kda not equal to 0 and kdv not equal to 0). Furthermore, the vergence and accommodation coefficients of near response cells appeared to be continuously distributed. Some cells had negative accommodation or vergence coefficients. 4. The 17 near response cells that could be antidromically activated from the oculomotor nucleus presumably provide vergence signals to the medial rectus motoneurons. Although all had positive vergence coefficients, only four of these cells carried signals that were related exclusively to vergence.(ABSTRACT TRUNCATED AT 400 WORDS)

Relationship between mandibular deviation and ocular convergence

2005 ◽  
Vol 28 (2) ◽  
pp. 135-138 ◽  
Author(s):  
A. Monaco ◽  
O. Streni ◽  
M. Marci ◽  
L. Sabetti ◽  
G. Marzo ◽  
...  
Keyword(s):  
Pediatric Dentistry ◽  
Interdisciplinary Cooperation ◽  
Controlled Study ◽  
Control Group ◽  
Study Group ◽  
Gender And Age ◽  
Mandibular Position ◽  
The Relationship ◽  
Ocular Convergence

Recent studies have confirmed the relationship between head posture, mandibular position and visual focusing. A case-controlled study was conducted to assess the occurrence of ocular convergence defects between subjects with functional mandibular latero-deviation and healthy subjects in pediatric age. Sixty subjects (the study group) presented mandibular latero-deviation classified as functional according to the use of a clinical examination and frontal and basal tele-radiography. Sixty subjects without functional mandibular laterodeviation (control group) were selected randomly from all subjects seeking pediatric dental care and matched by gender and age to study group. All one hundred and twenty subjects were submitted to orthoptic tests performed by the same operator. These results seemed to confirm that in mandibular latero-deviation subjects ocular convergence defects occurred in greater frequency than in controls underlining the importance of role of pediatric dentistry among interdisciplinary cooperation.

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