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Zoi Kapoula - One of the best experts on this subject based on the ideXlab platform.
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effects of pure Vergence training on initiation and binocular coordination of saccades
Investigative Ophthalmology & Visual Science, 2017Co-Authors: Aurelien Morize, Francois Daniel, Dominique Bremondgignac, Zoi KapoulaAbstract:Purpose We hypothesized that saccade eye movement properties, particularly latency and binocular coordination, depend on Vergence quality. Methods We studied 11 students clinically diagnosed for Vergence disorders versus 8 healthy controls. Rehabilitation of Vergence disorders was done with a novel research-based method, using Vergence in midsagittal plane. Vergence and saccades were recorded in separate blocks, before and after five weekly rehabilitation sessions. Results Healthy controls showed higher accuracy and velocity of conVergence and diVergence relative to the Vergence disorders group; then rehabilitation led to significant decrease of latency and increase of gain and peak velocity of Vergence. Before rehabilitation of the Vergence disorders, saccade parameters did not differ significantly from healthy controls, except the binocular coordination that was significantly deteriorated. Following Vergence rehabilitation, saccade properties improved: The latency decreased significantly, the gain increased particularly at far, and the binocular coordination improved significantly. Latency and accuracy improved in a durable way, with values even better than the range of accuracy measured in healthy controls; binocular coordination of saccades, although improved, did not normalize. In healthy controls, binocular coordination was optimal at 40 cm (working distance), and the Vergence disorders group showed improvement at 40 cm. Results confirm the hypothesis, which is further corroborated by the correlation between Vergence and saccade latency. Conclusions Results are in line with the hypothesis of permanent interaction between saccades and Vergence, even when the task requires only saccades. Relevance of such interaction is emphasized by improvements of binocular saccades through the novel research-based method of Vergence rehabilitation.
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Benefits from Vergence Rehabilitation: Evidence for Improvement of Reading Saccades and Fixations.
Frontiers in integrative neuroscience, 2016Co-Authors: Francois Daniel, Aurelien Morize, Dominique Bremond-gignac, Zoi KapoulaAbstract:We hypothesize that binocular coordination of saccades is based on continuous neuroplasticity involving interactions of saccades and Vergence. To test this hypothesis we study reading saccades in young students who were diagnosed for Vergence disorders before and after Vergence rehabilitation. Following orthoptic evaluation and symptomatology screening, five weekly sessions of Vergence rehabilitation were applied with the REMOBI Vergence double step protocole (see Kapoula et al., 2016). Using the Eyeseecam videoculography device we measured Vergence as well as saccades and fixations during a reading test four times: at the beginning and at the end of the first and of the fifth Vergence rehabilitation session. The results show elimination of symptoms, improvement of clinical orthoptic scores, and importantly increase of measured Vergence gain and reduction of inter-trial variability. Improvement of the Vergence was associated to a decrease of the disconjugacy of saccades during reading but also to shortening of fixation durations, to reduction of the number of regressive saccades and to a better correction of the intra-saccadic disconjugacy during the following fixation. The results corroborate the hypothesis of neuroplasticity based on saccade Vergence interaction in young adults. It validates the clinical validity of the Vergence double-step REMOBI method as a means to improve both, Vergence and reading performances. It opens a new research approach on the link between fine binocular coordination of saccades, quality of the Vergence response, attention, cognition and reading.
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objective evaluation of Vergence disorders and a research based novel method for Vergence rehabilitation
Translational Vision Science & Technology, 2016Co-Authors: Zoi Kapoula, Aurelien Morize, Francois Daniel, Fabienne Jonqua, Christophe Orssaud, Dominique BremondgignacAbstract:PURPOSE We performed video-oculography to evaluate Vergence eye movement abnormalities in students diagnosed clinically with Vergence disorders. We tested the efficiency of a novel rehabilitation method and evaluated its benefits with video-oculography cross-correlated with clinical tests and symptomatology. METHODS A total of 19 students (20-27 years old) underwent ophthalmologic, orthoptic examination, and a Vergence test coupled with video-oculography. Eight patients were diagnosed with Vergence disorders with a high symptomatology score (CISS) and performed a 5-week session of Vergence rehabilitation. Vergence and rehabilitation tasks were performed with a trapezoid surface of light emitting diodes (LEDs) and adjacent buzzers (US 8851669). We used a novel Vergence double-step (Vd-s) protocol: the target stepped to a second position before the Vergence movement completion. Afterward the Vergence test was repeated 1 week and 1 month later. RESULTS Abnormally increased intertrial variability was observed for many Vergence parameters (gain, duration, and speed) for the subjects with Vergence disorders. High CISS scores were correlated with variability and increased latency. After the Vd-s, variability of all parameters dropped to normal or better levels. Moreover, the conVergence and diVergence latency diminished significantly to levels better than normal; benefits were maintained 1 month after completion of Vd-s. CISS scores dropped to normal level, which was maintained up to 1 year. CONCLUSIONS AND TRANSLATIONAL RELEVANCE Intertrial variability is the major marker of Vergence disorders. The Vd-s research-based method leads to normalization of Vergence properties and lasting removal of symptoms. The efficiency of the method is due to the spatiotemporal parameters of repetitive trials that stimulate neural plasticity.
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Saccades and Vergence Performance in a Population of Children with Vertigo and Clinically Assessed Abnormal Vergence Capabilities
PLoS ONE, 2011Co-Authors: Maria Pia Bucci, Zoi Kapoula, Emmanuel Bui-quoc, Aurelie Bouet, Sylvette Wiener-vacherAbstract:Purpose: Early studies reported some abnormalities in saccade and Vergence eye movements in children with vertigo and Vergence deficiencies. The purpose of this study was to further examine saccade and Vergence performance in a population of 44 children (mean age: 12.361.6 years) with vertigo symptoms and with different levels of Vergence abnormalities, as assessed by static orthoptic examination (near point of conVergence, prism bar and cover-uncover test). Methods: Three groups were identified on the basis of the orthoptic tests: group 1 (n = 13) with Vergence spasms and mildly perturbed orthoptic scores, group 2 (n = 14) with moderately perturbed orthoptic scores, and group 3 (n = 17) with severely perturbed orthoptic scores. Data were compared to those recorded from 28 healthy children of similar ages. Latency, accuracy and peak velocity of saccades and Vergence movements were measured in two different conditions: gap (fixation offset 200 ms prior to target onset) and simultaneous paradigms. Binocular horizontal movements were recorded by a photoelectric device. Results: Group 2 of children with Vergence abnormalities showed significantly longer latency than normal children in several types of eye movements recorded. For all three groups of children with Vergence abnormalities, the gain was poor, particularly for Vergence movement. The peak velocity values did not differ between the different groups of children examined. Interpretation: Eye movement measures together with static orthoptic evaluation allowed us to better identify children with Vergence abnormalities based on their slow initiation of eye movements. Overall, these findings support the hypothesis of a central deficit in the programming and triggering of saccades and Vergence in these children.
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Saccades during symmetrical Vergence
Graefe's Archive for Clinical and Experimental Ophthalmology, 2008Co-Authors: Olivier A. Coubard, Zoi KapoulaAbstract:Background When the eyes verge symmetrically along the median plane from far to near (conVergence) or near to far (diVergence), small saccades often occur. The current study aimed to: (i) characterize saccades during symmetrical Vergence, (ii) describe the chronometry of saccade relative to that of Vergence, and (iii) determine whether saccades mediate prefrontal control of Vergence. Methods In Experiment 1, we recorded horizontal saccades during Vergence in ten normals using an infrared tracker. Transcranial magnetic stimulation (TMS) was delivered over dorsolateral prefrontal cortex to assess its contribution in saccade production. In Experiment 2, saccades during Vergence were recorded in horizontal and vertical planes in two other normals using a video-based tracker. Results Horizontal saccades, either pure or oblique (Exp.1), occurred in 84.0% of trials, 58 ms after Vergence onset, and averaged 1.5° in amplitude. An idiosyncratic directional bias to the right was found for the rate and the latency of saccades. Prefrontal TMS had no influence on any saccade parameter. Pure horizontal, pure vertical and oblique saccades (Exp.2) occurred, respectively, in 60.4%, 72.4% and 25.4% of trials, 168 ms, 121 ms and 146 ms after Vergence onset, averaging 1.1°, 1.2° and 1.5° in amplitude. Conclusions Chronometry of saccades during Vergence suggests that they do not participate to Vergence triggering, and that prefrontal control of Vergence previously reported was not mediated by saccades.
Tara L. Alvarez - One of the best experts on this subject based on the ideXlab platform.
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test retest reliability of functional magnetic resonance imaging activation for a Vergence eye movement task
Neuroscience Bulletin, 2020Co-Authors: Cristian Morales, Suril Gohel, Mitchell Scheiman, Bharat B. Biswal, Elio M. Santos, Chang Yaramothu, Tara L. AlvarezAbstract:Vergence eye movements are the inward and outward rotation of the eyes responsible for binocular coordination. While studies have mapped and investigated the neural substrates of Vergence, it is not well understood whether Vergence eye movements evoke the blood oxygen level-dependent signal reliably in separate experimental visits. The test–retest reliability of stimulus-induced Vergence eye movement tasks during a functional magnetic resonance imaging (fMRI) experiment is important for future randomized clinical trials (RCTs). In this study, we established region of interest (ROI) masks for the Vergence neural circuit. Twenty-seven binocularly normal young adults participated in two functional imaging sessions measured on different days on the same 3T Siemens scanner. The fMRI experiments used a block design of sustained visual fixation and rest blocks interleaved between task blocks that stimulated eight or four Vergence eye movements. The test–retest reliability of task-activation was assessed using the intraclass correlation coefficient (ICC), and that of spatial extent was assessed using the Dice coefficient. Functional activation during the Vergence eye movement task of eight movements compared to rest was repeatable within the primary visual cortex (ICC = 0.8), parietal eye fields (ICC = 0.6), supplementary eye field (ICC = 0.5), frontal eye fields (ICC = 0.5), and oculomotor vermis (ICC = 0.6). The results demonstrate significant test–retest reliability in the ROIs of the Vergence neural substrates for functional activation magnitude and spatial extent using the stimulus protocol of a task block stimulating eight Vergence eye movements compared to sustained fixation. These ROIs can be used in future longitudinal RCTs to study patient populations with Vergence dysfunctions.
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Test–Retest Reliability of Functional Magnetic Resonance Imaging Activation for a Vergence Eye Movement Task
Neuroscience Bulletin, 2019Co-Authors: Cristian Morales, Suril Gohel, Xiaobo Li, Mitchell Scheiman, Bharat B. Biswal, Elio M. Santos, Chang Yaramothu, Tara L. AlvarezAbstract:Vergence eye movements are the inward and outward rotation of the eyes responsible for binocular coordination. While studies have mapped and investigated the neural substrates of Vergence, it is not well understood whether Vergence eye movements evoke the blood oxygen level-dependent signal reliably in separate experimental visits. The test–retest reliability of stimulus-induced Vergence eye movement tasks during a functional magnetic resonance imaging (fMRI) experiment is important for future randomized clinical trials (RCTs). In this study, we established region of interest (ROI) masks for the Vergence neural circuit. Twenty-seven binocularly normal young adults participated in two functional imaging sessions measured on different days on the same 3T Siemens scanner. The fMRI experiments used a block design of sustained visual fixation and rest blocks interleaved between task blocks that stimulated eight or four Vergence eye movements. The test–retest reliability of task-activation was assessed using the intraclass correlation coefficient (ICC), and that of spatial extent was assessed using the Dice coefficient. Functional activation during the Vergence eye movement task of eight movements compared to rest was repeatable within the primary visual cortex (ICC = 0.8), parietal eye fields (ICC = 0.6), supplementary eye field (ICC = 0.5), frontal eye fields (ICC = 0.5), and oculomotor vermis (ICC = 0.6). The results demonstrate significant test–retest reliability in the ROIs of the Vergence neural substrates for functional activation magnitude and spatial extent using the stimulus protocol of a task block stimulating eight Vergence eye movements compared to sustained fixation. These ROIs can be used in future longitudinal RCTs to study patient populations with Vergence dysfunctions.
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Disparity Vergence responses before versus after repetitive Vergence therapy in binocularly normal controls
Journal of vision, 2016Co-Authors: Henry Talasan, Mitchell Scheiman, Tara L. AlvarezAbstract:This study sought to determine whether significant changes would be observed between Vergence eye movements before and after 12 hr of repetitive Vergence therapy (1 hr per day on different days) in subjects with normal binocular vision compared to controls. Disparity Vergence responses from 23 subjects were studied. An assessment protocol that minimized the influence of the near dissociated phoria on the disparity Vergence system was designed. The following parameters were quantified for the responses: latency, time to peak velocity, settling time, peak velocity, and accuracy (difference between the response and stimulus amplitudes). The following outcomes were observed when comparing the results after Vergence therapy to the baseline measurements: (a) near point of conVergence and near dissociated phoria did not significantly change (p > 0.15); (b) latency, time to peak velocity, and settling time significantly decreased (p ≤ 0.01); and (c) accuracy significantly improved (p < 0.01). Results support that Vergence peak velocity is dependent on the subject's near dissociated phoria. The accuracy and temporal properties of Vergence eye movement responses from subjects with normal binocular vision can be improved after Vergence therapy. These methods can be utilized within future studies to quantitatively assess Vergence therapy techniques for patients with binocular dysfunction.
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A pilot study of disparity Vergence and near dissociated phoria in conVergence insufficiency patients before vs. after Vergence therapy.
Frontiers in human neuroscience, 2015Co-Authors: Tara L. AlvarezAbstract:PURPOSE: This study examined the relationship between the near dissociated phoria and disparity Vergence eye movements. ConVergence insufficiency (CI) patients before Vergence therapy were compared to: 1) the same patients after Vergence therapy and 2) binocularly normal controls (BNC). METHODS: Sixteen subjects were studied--twelve BNC and four with CI. Measurements from the CI subjects were obtained before and after 18 hours of Vergence eye movement therapy. The near dissociated phoria was measured using the flashed Maddox rod technique. Vergence responses were stimulated from 4° symmetrical disparity Vergence step stimuli. The peak velocity of the Vergence response and the magnitude of the fusion initiating component (FIC) from an independent component analysis were calculated. A linear regression analysis was conducted studying the Vergence peak velocity as a function of the near dissociated phoria where the Pearson correlation coefficient was computed. RESULTS: Before Vergence therapy, the average with one standard deviation FIC magnitude of conVergence responses from CI subjects was 0.290.82 and significantly less than the FIC magnitude of 1.850.84 for BNC (p
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EMBC - The frequency of saccades correlates to peak velocity in symmetrical disparity Vergence
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Inte, 2011Co-Authors: Eun H. Kim, Tara L. AlvarezAbstract:A pure Vergence stimulus requires the two eyes to turn equally inward or outward theoretically resulting in a pure symmetrical Vergence response. However, saccades, a rapid conjugate eye movement, are frequently observed in Vergence responses. This investigation sought to systematically quantify whether the occurrence of saccades within symmetrical Vergence responses is correlated to Vergence peak velocity. Eye movements are quantified using a limbus tracking system from three subjects. Symmetrical conVergence and diVergence 4° step responses with an initial position located at far or near which are known to evoke different peak velocities are analyzed. Data are quantified via peak velocity. A saccade detecting algorithm is utilized to quantify the frequency of saccades in the transient portion (first second) of Vergence responses. Near conVergence responses are slower than far conVergence and far diVergence responses are slower compared to near diVergence movements. The occurrence of saccades is negatively correlated to Vergence peak velocity. When the velocity is slower, the number of saccades increases. This study suggests that the brain may initiate a saccade to facilitate a slow Vergence movement, potentially to allow object recognition before binocular fusion.
Christoph Helmchen - One of the best experts on this subject based on the ideXlab platform.
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Vergence Deficits in Patients with Cerebellar Lesions.
Brain, 2008Co-Authors: T. Sander, Holger Rambold, G. Neumann, Andreas Sprenger, Björn Machner, S. Gottschalk, Christoph HelmchenAbstract:The cerebellum is part of the cortico-ponto-cerebellar circuit for conjugate eye movements. Recent animal data suggest an additional role of the cerebellum for the control of binocular alignment and disconjugate, i.e. Vergence eye movements. The latter is separated into two different components: fast Vergence (to step targets) and slow Vergence (to ramp and sinusoidal targets). The aim of this study was to investigate whether circumscribed cerebellar lesions affect these dynamic Vergence eye movements. Disconjugate fast and slow Vergence, conjugate smooth pursuit and saccades were binocularly recorded by a scleral search coil system in 20 patients with acute cerebellar lesions (all ischemic strokes except for one) and 20 age-matched healthy controls. Patients showed impairment of slow Vergence while fast Vergence was unaffected. Slow Vergence gain to sinusoidal targets was significantly reduced, both in conVergence and diVergence direction. DiVergence but not conVergence velocity to ramp targets was reduced. Conjugate smooth pursuit eye movements to sinusoidal and to step-ramp targets were impaired. Patients had saccadic hypometria. All defects were particularly expressed in patients with vermis lesions. In contrast to recent animal data fast Vergence was not impaired in any of our patient subgroups. We conclude that (i) the human cerebellum, in particular the vermis, is involved in the processing of dynamic Vergence eye movements and (ii) cerebellar lesions elicit dissociable effects on fast and slow Vergence.
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Palsy of “fast” and “slow” Vergence by pontine lesions
Neurology, 2005Co-Authors: Holger Rambold, G. Neumann, T. Sander, Christoph HelmchenAbstract:The role of pontine nuclei in Vergence eye movements to “step” targets (“fast” Vergence) is unknown. Eye movements were recorded in two patients with unilateral pontine infarctions and in 11 healthy controls. In addition to the deficit of “slow” Vergence, “fast” Vergence was particularly impaired. However, conjugate saccades did not differ from controls, but smooth pursuit eye movements did. The authors conclude that “fast” Vergence palsy is not only caused by midbrain but also upper pontine lesions.
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Pontine Lesions May Cause Selective Deficits of “Slow” Vergence Eye Movements
Annals of the New York Academy of Sciences, 2005Co-Authors: Holger Rambold, G. Neumann, T. Sander, Christoph HelmchenAbstract:To address the role of pontine nuclei in Vergence control, eye movements to ramp ('slow Vergence') and step targets ('fast Vergence') were recorded in two patients with unilateral mediolateral pontine infarctions and in ten healthy controls. 'Slow' Vergence and conjugate smooth pursuit eye movements were impaired while 'fast' Vergence was not. We conclude that like smooth pursuit signals, Vergence signals are distributed in the pontine nuclei.
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Vergence deficits in pontine lesions
Neurology, 2004Co-Authors: Holger Rambold, G. Neumann, Christoph HelmchenAbstract:Eye movements were recorded with the search coil system in two patients to determine whether lesions of the pontine nuclei selectively impair Vergence to ramp targets (slow Vergence) or step targets (fast Vergence). Whereas conjugate saccades were not different from healthy control subjects, conjugate smooth pursuit eye movements had a reduced gain in horizontal and vertical directions. Slow conVergence and diVergence were impaired, whereas fast Vergence did not differ from that of control subjects. Pontine nuclei appear to be involved in the slow Vergence control.
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Blink effect on slow Vergence.
Neuroreport, 2002Co-Authors: Holger Rambold, G. Neumann, Andreas Sprenger, Christoph HelmchenAbstract:Blinks are known to change the kinematic properties of fast eye movements, probably by changes in the brain stem circuits. To determine whether slow disconjugate (slow Vergence) eye movements are affected by blinks under natural viewing conditions, we elicited airpuff-evoked trigeminal blinks randomly during ongoing steady slow Vergence eye movements. Lid and binocular eye movements were recorded by the scleral search coil method. Slow Vergence eye movements showed a peak of Vergence velocity during the final part of the blink, which depends on the stimulus direction. We propose that the direction-specific blink effect on slow Vergence may be caused by changes in brain stem premotor circuits.
Holger Rambold - One of the best experts on this subject based on the ideXlab platform.
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Vergence Deficits in Patients with Cerebellar Lesions.
Brain, 2008Co-Authors: T. Sander, Holger Rambold, G. Neumann, Andreas Sprenger, Björn Machner, S. Gottschalk, Christoph HelmchenAbstract:The cerebellum is part of the cortico-ponto-cerebellar circuit for conjugate eye movements. Recent animal data suggest an additional role of the cerebellum for the control of binocular alignment and disconjugate, i.e. Vergence eye movements. The latter is separated into two different components: fast Vergence (to step targets) and slow Vergence (to ramp and sinusoidal targets). The aim of this study was to investigate whether circumscribed cerebellar lesions affect these dynamic Vergence eye movements. Disconjugate fast and slow Vergence, conjugate smooth pursuit and saccades were binocularly recorded by a scleral search coil system in 20 patients with acute cerebellar lesions (all ischemic strokes except for one) and 20 age-matched healthy controls. Patients showed impairment of slow Vergence while fast Vergence was unaffected. Slow Vergence gain to sinusoidal targets was significantly reduced, both in conVergence and diVergence direction. DiVergence but not conVergence velocity to ramp targets was reduced. Conjugate smooth pursuit eye movements to sinusoidal and to step-ramp targets were impaired. Patients had saccadic hypometria. All defects were particularly expressed in patients with vermis lesions. In contrast to recent animal data fast Vergence was not impaired in any of our patient subgroups. We conclude that (i) the human cerebellum, in particular the vermis, is involved in the processing of dynamic Vergence eye movements and (ii) cerebellar lesions elicit dissociable effects on fast and slow Vergence.
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Palsy of “fast” and “slow” Vergence by pontine lesions
Neurology, 2005Co-Authors: Holger Rambold, G. Neumann, T. Sander, Christoph HelmchenAbstract:The role of pontine nuclei in Vergence eye movements to “step” targets (“fast” Vergence) is unknown. Eye movements were recorded in two patients with unilateral pontine infarctions and in 11 healthy controls. In addition to the deficit of “slow” Vergence, “fast” Vergence was particularly impaired. However, conjugate saccades did not differ from controls, but smooth pursuit eye movements did. The authors conclude that “fast” Vergence palsy is not only caused by midbrain but also upper pontine lesions.
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Pontine Lesions May Cause Selective Deficits of “Slow” Vergence Eye Movements
Annals of the New York Academy of Sciences, 2005Co-Authors: Holger Rambold, G. Neumann, T. Sander, Christoph HelmchenAbstract:To address the role of pontine nuclei in Vergence control, eye movements to ramp ('slow Vergence') and step targets ('fast Vergence') were recorded in two patients with unilateral mediolateral pontine infarctions and in ten healthy controls. 'Slow' Vergence and conjugate smooth pursuit eye movements were impaired while 'fast' Vergence was not. We conclude that like smooth pursuit signals, Vergence signals are distributed in the pontine nuclei.
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Vergence deficits in pontine lesions
Neurology, 2004Co-Authors: Holger Rambold, G. Neumann, Christoph HelmchenAbstract:Eye movements were recorded with the search coil system in two patients to determine whether lesions of the pontine nuclei selectively impair Vergence to ramp targets (slow Vergence) or step targets (fast Vergence). Whereas conjugate saccades were not different from healthy control subjects, conjugate smooth pursuit eye movements had a reduced gain in horizontal and vertical directions. Slow conVergence and diVergence were impaired, whereas fast Vergence did not differ from that of control subjects. Pontine nuclei appear to be involved in the slow Vergence control.
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Blink effect on slow Vergence.
Neuroreport, 2002Co-Authors: Holger Rambold, G. Neumann, Andreas Sprenger, Christoph HelmchenAbstract:Blinks are known to change the kinematic properties of fast eye movements, probably by changes in the brain stem circuits. To determine whether slow disconjugate (slow Vergence) eye movements are affected by blinks under natural viewing conditions, we elicited airpuff-evoked trigeminal blinks randomly during ongoing steady slow Vergence eye movements. Lid and binocular eye movements were recorded by the scleral search coil method. Slow Vergence eye movements showed a peak of Vergence velocity during the final part of the blink, which depends on the stimulus direction. We propose that the direction-specific blink effect on slow Vergence may be caused by changes in brain stem premotor circuits.
G. Neumann - One of the best experts on this subject based on the ideXlab platform.
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Vergence Deficits in Patients with Cerebellar Lesions.
Brain, 2008Co-Authors: T. Sander, Holger Rambold, G. Neumann, Andreas Sprenger, Björn Machner, S. Gottschalk, Christoph HelmchenAbstract:The cerebellum is part of the cortico-ponto-cerebellar circuit for conjugate eye movements. Recent animal data suggest an additional role of the cerebellum for the control of binocular alignment and disconjugate, i.e. Vergence eye movements. The latter is separated into two different components: fast Vergence (to step targets) and slow Vergence (to ramp and sinusoidal targets). The aim of this study was to investigate whether circumscribed cerebellar lesions affect these dynamic Vergence eye movements. Disconjugate fast and slow Vergence, conjugate smooth pursuit and saccades were binocularly recorded by a scleral search coil system in 20 patients with acute cerebellar lesions (all ischemic strokes except for one) and 20 age-matched healthy controls. Patients showed impairment of slow Vergence while fast Vergence was unaffected. Slow Vergence gain to sinusoidal targets was significantly reduced, both in conVergence and diVergence direction. DiVergence but not conVergence velocity to ramp targets was reduced. Conjugate smooth pursuit eye movements to sinusoidal and to step-ramp targets were impaired. Patients had saccadic hypometria. All defects were particularly expressed in patients with vermis lesions. In contrast to recent animal data fast Vergence was not impaired in any of our patient subgroups. We conclude that (i) the human cerebellum, in particular the vermis, is involved in the processing of dynamic Vergence eye movements and (ii) cerebellar lesions elicit dissociable effects on fast and slow Vergence.
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Palsy of “fast” and “slow” Vergence by pontine lesions
Neurology, 2005Co-Authors: Holger Rambold, G. Neumann, T. Sander, Christoph HelmchenAbstract:The role of pontine nuclei in Vergence eye movements to “step” targets (“fast” Vergence) is unknown. Eye movements were recorded in two patients with unilateral pontine infarctions and in 11 healthy controls. In addition to the deficit of “slow” Vergence, “fast” Vergence was particularly impaired. However, conjugate saccades did not differ from controls, but smooth pursuit eye movements did. The authors conclude that “fast” Vergence palsy is not only caused by midbrain but also upper pontine lesions.
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Pontine Lesions May Cause Selective Deficits of “Slow” Vergence Eye Movements
Annals of the New York Academy of Sciences, 2005Co-Authors: Holger Rambold, G. Neumann, T. Sander, Christoph HelmchenAbstract:To address the role of pontine nuclei in Vergence control, eye movements to ramp ('slow Vergence') and step targets ('fast Vergence') were recorded in two patients with unilateral mediolateral pontine infarctions and in ten healthy controls. 'Slow' Vergence and conjugate smooth pursuit eye movements were impaired while 'fast' Vergence was not. We conclude that like smooth pursuit signals, Vergence signals are distributed in the pontine nuclei.
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Vergence deficits in pontine lesions
Neurology, 2004Co-Authors: Holger Rambold, G. Neumann, Christoph HelmchenAbstract:Eye movements were recorded with the search coil system in two patients to determine whether lesions of the pontine nuclei selectively impair Vergence to ramp targets (slow Vergence) or step targets (fast Vergence). Whereas conjugate saccades were not different from healthy control subjects, conjugate smooth pursuit eye movements had a reduced gain in horizontal and vertical directions. Slow conVergence and diVergence were impaired, whereas fast Vergence did not differ from that of control subjects. Pontine nuclei appear to be involved in the slow Vergence control.
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Blink effect on slow Vergence.
Neuroreport, 2002Co-Authors: Holger Rambold, G. Neumann, Andreas Sprenger, Christoph HelmchenAbstract:Blinks are known to change the kinematic properties of fast eye movements, probably by changes in the brain stem circuits. To determine whether slow disconjugate (slow Vergence) eye movements are affected by blinks under natural viewing conditions, we elicited airpuff-evoked trigeminal blinks randomly during ongoing steady slow Vergence eye movements. Lid and binocular eye movements were recorded by the scleral search coil method. Slow Vergence eye movements showed a peak of Vergence velocity during the final part of the blink, which depends on the stimulus direction. We propose that the direction-specific blink effect on slow Vergence may be caused by changes in brain stem premotor circuits.