The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform

T Mergner - One of the best experts on this subject based on the ideXlab platform.

T Mergner - One of the best experts on this subject based on the ideXlab platform.

  • gaze stabilization by Optokinetic Reflex okr and vestibulo ocular Reflex vor during active head rotation in man
    Vision Research, 1997
    Co-Authors: G Schweigart, T Mergner, I Evdokimidis, Stephanie Morand, W Becker
    Abstract:

    Abstract Vestibulo-ocular Reflex (VOR)-Optokinetic Reflex (OKR) interaction was studied in normal human subjects during active sine-like head movements in the horizontal plane for a variety of vestibular-Optokinetic stimulus combinations (frequency range, 0.05–1.6 Hz). At low to mid frequencies (

  • combined action of Optokinetic Reflex okr and vestibulo ocular Reflex vor in macaque monkey during transient stimulation
    Neuroscience Letters, 1995
    Co-Authors: G Schweigart, T Mergner
    Abstract:

    Abstract Interaction of vestibulo-ocular Reflex (VOR) and Optokinetic Reflex (OKR) was studied in macaque monkeys by recording horizontal eye movements during transient rotations of their heads and/or Optokinetic pattern in space. At low peak velocities of the stimuli (1.25°/s, 10.0°/s) the eyes were rather well stabilized on the Optokinetic pattern, independently of whether the head, the pattern, or both were rotated. At higher velocities (40.0°/s), the OKR gain was attenuated and, when combining vestibular and Optokinetic stimuli, the eyes became increasingly stabilized in space. The data could be simulated by a computer model previously designed to describe VOR-OKR interaction during sinusoidal rotations. In this model eye stabilization primarily relies on the OKR, while the role of the VOR is to compensate for the limited bandwidth of the OKR.

  • interaction of Optokinetic Reflex and vestibulo ocular Reflex during active and passive head rotation
    1995
    Co-Authors: G Schweigart, T Mergner, Stephanie Morand, I Evdokimidis
    Abstract:

    For accurate vision, we have to stabilize the visual images in our eyes on the fovea. During head movements, this goal is mainly achieved by the combined actions of the vestibulo-ocular Reflex (VOR) and the Optokinetic Reflex (OKR). The VOR is evoked by head movements in space and gives rise to a compensatory counter-rotation of the eyes in the orbits, with the aim to stabilize the eyes in space. Accordingly, the VOR contributes to clear vision only if the visual scene is stationary during self-motion. The OKR, on the other hand, tries to zero relative motion between visual scene and retina, thereby improving vision independently of whether the scene, the head or both are moving. Therefore, the OKR would be better apt than the VOR to guarantee accurate vision. However, the OKR suffers from limited band width at high temporal frequencies (see Barnes, 1993).

Edward A Burton - One of the best experts on this subject based on the ideXlab platform.

  • modulation of the zebrafish Optokinetic Reflex by pharmacologic agents targeting gabaa receptors
    Neuroscience Letters, 2018
    Co-Authors: Enhua Shao, Seth Scheetz, Edward A Burton
    Abstract:

    Abstract Optokinetic Reflex (OKR) responses provide a convenient means to evaluate visual, integrative and oculomotor function in larval zebrafish. We measured multiple aspects of the OKR response in zebrafish exposed systemically to compounds altering signaling at GABAA receptors in order to derive quantitative concentration-response relationships. The GABAA antagonist picrotoxin caused concentration-dependent decreases in Reflex gain, saccade velocity, saccade amplitude, interocular concordance and interocular gain. Conversely, the GABAA agonist gaboxadol provoked increases in Reflex gain, saccade velocity, saccade amplitude and ocular range at low concentrations, and decreases in some of these parameters at higher concentrations. These data show that GABAA signaling influences multiple aspects of the OKR (including gain, generation of saccades, and coordination between the two eyes) and provide proof of concept that quantitative OKR analysis can be used as a tool for chemical biology and neuropharmacology applications.

  • an open source method to analyze Optokinetic Reflex responses in larval zebrafish
    Journal of Neuroscience Methods, 2018
    Co-Authors: Seth Scheetz, Enhua Shao, Yangzhong Zhou, Clinton L Cario, Edward A Burton
    Abstract:

    Abstract Background Optokinetic Reflex (OKR) responses provide a convenient means to evaluate oculomotor, integrative and afferent visual function in larval zebrafish models, which are commonly used to elucidate molecular mechanisms underlying development, disease and repair of the vertebrate nervous system. New method We developed an open-source MATLAB-based solution for automated quantitative analysis of OKR responses in larval zebrafish. The package includes applications to: (i) generate sinusoidally-transformed animated grating patterns suitable for projection onto a cylindrical screen to elicit the OKR; (ii) determine and record the angular orientations of the eyes in each frame of a video recording showing the OKR response; and (iii) analyze angular orientation data from the tracking program to yield a set of parameters that quantify essential elements of the OKR. The method can be employed without modification using the operating manual provided. In addition, annotated source code is included, allowing users to modify or adapt the software for other applications. Results We validated the algorithms and measured OKR responses in normal larval zebrafish, showing good agreement with published quantitative data, where available. Comparison with existing method(s) We provide the first open-source method to elicit and analyze the OKR in larval zebrafish. The wide range of parameters that are automatically quantified by our algorithms significantly expands the scope of quantitative analysis previously reported. Conclusions Our method for quantifying OKR responses will be useful for numerous applications in neuroscience using the genetically- and chemically-tractable zebrafish model.

G Schweigart - One of the best experts on this subject based on the ideXlab platform.

  • gaze stabilization by Optokinetic Reflex okr and vestibulo ocular Reflex vor during active head rotation in man
    Vision Research, 1997
    Co-Authors: G Schweigart, T Mergner, I Evdokimidis, Stephanie Morand, W Becker
    Abstract:

    Abstract Vestibulo-ocular Reflex (VOR)-Optokinetic Reflex (OKR) interaction was studied in normal human subjects during active sine-like head movements in the horizontal plane for a variety of vestibular-Optokinetic stimulus combinations (frequency range, 0.05–1.6 Hz). At low to mid frequencies (

  • combined action of Optokinetic Reflex okr and vestibulo ocular Reflex vor in macaque monkey during transient stimulation
    Neuroscience Letters, 1995
    Co-Authors: G Schweigart, T Mergner
    Abstract:

    Abstract Interaction of vestibulo-ocular Reflex (VOR) and Optokinetic Reflex (OKR) was studied in macaque monkeys by recording horizontal eye movements during transient rotations of their heads and/or Optokinetic pattern in space. At low peak velocities of the stimuli (1.25°/s, 10.0°/s) the eyes were rather well stabilized on the Optokinetic pattern, independently of whether the head, the pattern, or both were rotated. At higher velocities (40.0°/s), the OKR gain was attenuated and, when combining vestibular and Optokinetic stimuli, the eyes became increasingly stabilized in space. The data could be simulated by a computer model previously designed to describe VOR-OKR interaction during sinusoidal rotations. In this model eye stabilization primarily relies on the OKR, while the role of the VOR is to compensate for the limited bandwidth of the OKR.

  • interaction of Optokinetic Reflex and vestibulo ocular Reflex during active and passive head rotation
    1995
    Co-Authors: G Schweigart, T Mergner, Stephanie Morand, I Evdokimidis
    Abstract:

    For accurate vision, we have to stabilize the visual images in our eyes on the fovea. During head movements, this goal is mainly achieved by the combined actions of the vestibulo-ocular Reflex (VOR) and the Optokinetic Reflex (OKR). The VOR is evoked by head movements in space and gives rise to a compensatory counter-rotation of the eyes in the orbits, with the aim to stabilize the eyes in space. Accordingly, the VOR contributes to clear vision only if the visual scene is stationary during self-motion. The OKR, on the other hand, tries to zero relative motion between visual scene and retina, thereby improving vision independently of whether the scene, the head or both are moving. Therefore, the OKR would be better apt than the VOR to guarantee accurate vision. However, the OKR suffers from limited band width at high temporal frequencies (see Barnes, 1993).

W Becker - One of the best experts on this subject based on the ideXlab platform.

  • Eye stabilization by vestibulo-ocular Reflex (VOR) and Optokinetic Reflex (OKR) in macaque monkey: which helps which?
    Acta Oto-laryngologica, 2009
    Co-Authors: G Schweigart, T Mergner, W Becker
    Abstract:

    VOR-OKR interaction was studied in macaque monkey in the frequency domain, using various vestibular-visual stimulus combinations in the horizontal plane. At low stimulus frequencies (

  • circular vection during voluntary suppression of Optokinetic Reflex
    Experimental Brain Research, 2002
    Co-Authors: W Becker, Sabine Raab, R Jurgens
    Abstract:

    Optokinetic circular vection (CV) was investigated in 12 subjects using an Optokinetic pattern rotating at 15°/s, 30°/s, or 60°/s, and four viewing conditions: FOL, subjects attentively followed details of pattern; STA, subjects stared at the pattern; SUP, subjects suppressed their Optokinetic Reflex (OKR) voluntarily (this was facilitated by a white, featureless band at eye level which separated the pattern in an upper and lower half); FIX, subjects suppressed OKR by fixating at a stationary fixation point (FP). To quantify CV, subjects pressed a signal button each time they felt rotated by a further 90°; OKR was recorded by electro-oculography. Voluntary suppression of OKR was achieved during 2–70% of stimulus duration. Total apparent self-displacement (cumulated 90° indications) was smallest during FOL, increasing gradually in the order FOL < STA < SUP < FIX (all inequalities significant); CV latency decreased in the same order. Slow eye velocity was identical during FOL and STA, and was reduced by 70–30% during SUP. We conclude from these results: (1) the effect of eye movements on CV depends on whether these are intentional (FOL) or not (STA); (2) the increase in CV during voluntary OKR suppression without FP suggests that afferent motion cues (retinal slip) are processed with larger gain than efferent motion cues (eye movement); hence (3) the enhancement of CV during fixation of FP is not, or not solely, the result of the apparent motion of the FP counter to the direction of pattern movement (Duncker illusion).

  • gaze stabilization by Optokinetic Reflex okr and vestibulo ocular Reflex vor during active head rotation in man
    Vision Research, 1997
    Co-Authors: G Schweigart, T Mergner, I Evdokimidis, Stephanie Morand, W Becker
    Abstract:

    Abstract Vestibulo-ocular Reflex (VOR)-Optokinetic Reflex (OKR) interaction was studied in normal human subjects during active sine-like head movements in the horizontal plane for a variety of vestibular-Optokinetic stimulus combinations (frequency range, 0.05–1.6 Hz). At low to mid frequencies (

  • eye stabilization by vestibulo ocular Reflex vor and Optokinetic Reflex okr in macaque monkey which helps which
    Acta Oto-laryngologica, 1995
    Co-Authors: G Schweigart, T Mergner, W Becker
    Abstract:

    VOR-OKR interaction was studied in macaque monkey in the frequency domain, using various vestibular-visual stimulus combinations in the horizontal plane. At low stimulus frequencies (<0.1 HZ). the eyes were always stabilized on the Optokinetic pattern, irrespective of whether the head, the pattern, or both were rotated. At higher frequencies, the gain of the OKR attenuated, and concomitantly the eyes became increasingly stabilized in space. These findings show that the VOR becomes functionally relevant only at high frequencies. It compensates for the limited bandwidth of the OKR. thereby improving vision provided the pattern to be fixated is stationary in space.