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Kordek D, Voda P, Young LK, Kremlacek J. Effect of Dioptric Blur on Pattern-Reversal and Motion-Onset VEPs as Used in Clinical Research. Transl Vis Sci Technol 2022; 11:7. [PMID: 36472879 PMCID: PMC9733653 DOI: 10.1167/tvst.11.12.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Purpose To describe the effect of dioptric blur on visual evoked potentials (VEPs) induced by motion onset (MO-VEPs). Methods The effect of dioptric blur up to 4 D on MO-VEPs was tested on 12 subjects using central, peripheral, and full-field stimulation with a low-contrast structure of concentric circles with spatial frequency <1 c/°. The results were compared to VEPs evoked by 15' and 60' checkerboard pattern-reversal (PR-VEPs). The relationship between peak time and interpeak amplitude of the dominant components was related to the level of dioptric blur using linear regression. Results The MO-VEPs did not show a significant peak prolongation (P > 0.28) or amplitude attenuation (P > 0.14) with the blur, whereas for the PR-VEPs we observed a significant decrease in amplitude (P < 0.001) and increase in peak time (P < 0.001) for both checkerboard sizes. Conclusions For MO-VEPs induced by radial motion of low contrast and low spatial frequency pattern, the change in retinal blur does not affect the peak time or the interpeak amplitude of the dominant N2 component. Translational Relevance The resistance to retinal blur that we demonstrated for MO-VEP provides a diagnostic opportunity to test the integrity of the visual system and reveal a retrobulbar impairment even in uncorrected refractive errors.
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Affiliation(s)
- David Kordek
- Department of Biophysics, Faculty of Medicine, Charles University, Hradec Kralove, Czech Republic
| | - Petr Voda
- Department of Biophysics, Faculty of Medicine, Charles University, Hradec Kralove, Czech Republic
| | - Laura K. Young
- Biosciences Institute, Newcastle University, Newcastle, UK
| | - Jan Kremlacek
- Department of Biophysics, Faculty of Medicine, Charles University, Hradec Kralove, Czech Republic
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Scanlon JEM, Jacobsen NSJ, Maack MC, Debener S. Does the electrode amplification style matter? A comparison of active and passive EEG system configurations during standing and walking. Eur J Neurosci 2020; 54:8381-8395. [PMID: 33185920 DOI: 10.1111/ejn.15037] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 09/17/2020] [Accepted: 10/26/2020] [Indexed: 11/30/2022]
Abstract
It has been stated that active-transmission electrodes should improve signal quality in mobile EEG recordings. However, few studies have directly compared active- and passive-transmission electrodes during a mobile task. In this repeated measurement study, we investigated the performance of active and passive signal transmission electrodes with the same amplifier system in their respective typical configurations, during a mobile auditory task. The task was an auditory discrimination (1,000 vs. 800 Hz; counterbalanced) oddball task using approximately 560 trials (15% targets) for each condition. Eighteen participants performed the auditory oddball task both while standing and walking in an outdoor environment. While walking, there was a significant decrease in P3 amplitude, post-trial rejection trial numbers, and signal-to-noise ratio (SNR). No significant differences were found in signal quality between the two electrode configurations. SNR and P3 amplitude were test-retest reliable between recordings. We conclude that adequate use of a passive EEG electrode system achieves signal quality equivalent to that of an active system during a mobile task.
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Affiliation(s)
- Joanna E M Scanlon
- Neuropsychology Lab, Department of Psychology, University of Oldenburg, Oldenburg, Germany
| | | | - Marike C Maack
- Neuropsychology Lab, Department of Psychology, University of Oldenburg, Oldenburg, Germany
| | - Stefan Debener
- Neuropsychology Lab, Department of Psychology, University of Oldenburg, Oldenburg, Germany.,Cluster of Excellence Hearing4all, University of Oldenburg, Oldenburg, Germany.,Center for Neurosensory Science and Systems, University of Oldenburg, Oldenburg, Germany
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Kelly JP, Phillips JO, Weiss AH. The relationship of nystagmus waveform on the VEP response in infantile nystagmus syndrome: a small case series. Doc Ophthalmol 2017; 134:37-44. [PMID: 28054161 DOI: 10.1007/s10633-016-9568-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 12/14/2016] [Indexed: 11/26/2022]
Abstract
PURPOSE The relationship between eye movements and the visual evoked potential (VEP) response was examined in two subjects with infantile nystagmus syndrome (INS). Changes in VEP amplitude were compared between periods of foveation versus periods of high-frequency nystagmus. An analysis is proposed that improves extraction of the checkerboard reversal VEP signal from subjects with INS. METHODS INS subjects were 2 healthy children (12-13 years old) with 20/40 or better corrected acuity. Optical coherence tomography confirmed the optic nerves, retina, and fovea were within normal variation. VEPs were recorded to checkerboard reversal and to onset/offset of horizontal gratings while simultaneously recording the electrooculogram (EOG). VEP epochs underwent Fourier analysis, and epochs were examined for phase consistency with the mean. Foveation periods were compared to video-oculography recordings from a separate session. RESULTS Optic nerve misrouting, such as crossed VEP asymmetry seen in albinism, or ipsilateral VEP asymmetry seen in achiasma, was not detected in either subject. By averaging only epochs in which EOG epochs showed foveation, VEP amplitude could be increased ≥59%. Averaging the VEP only on epochs with consistent phase at Oz increased VEP amplitude by ≥twofold; subsequent EOG epochs after this analysis mostly contained foveation periods or minimal EOG activity. Latency varied <14 ms across all analyses. CONCLUSIONS The checkerboard reversal VEP signal is dependent on foveation periods in subjects with INS despite good visual acuity. Reduction in VEP amplitude due to retinal image motion induces noise and/or lack of phase locking in the VEP epochs. Selective averaging of epochs based on phase consistency improves the extraction of a VEP signal, likely when retinal image motion is minimized.
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Affiliation(s)
- John P Kelly
- Division of Ophthalmology, Roger H. Johnson Vision Lab, Seattle Children's Hospital, OA.5.345, 4800 Sand Point Way NE, W-4753, Seattle, WA, 98105, USA.
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, 98105, USA.
| | - James O Phillips
- Division of Ophthalmology, Roger H. Johnson Vision Lab, Seattle Children's Hospital, OA.5.345, 4800 Sand Point Way NE, W-4753, Seattle, WA, 98105, USA
- Department of Otolaryngology, University of Washington School of Medicine, Seattle, WA, 98105, USA
| | - Avery H Weiss
- Division of Ophthalmology, Roger H. Johnson Vision Lab, Seattle Children's Hospital, OA.5.345, 4800 Sand Point Way NE, W-4753, Seattle, WA, 98105, USA
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, 98105, USA
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Kelly JP, Phillips JO, Weiss AH. VEP analysis methods in children with optic nerve hypoplasia: relationship to visual acuity and optic disc diameter. Doc Ophthalmol 2016; 133:159-169. [PMID: 27882486 DOI: 10.1007/s10633-016-9566-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/15/2016] [Indexed: 11/27/2022]
Abstract
PURPOSE Assessing vision in young children with optic nerve hypoplasia (ONH) is challenging due to multi-directional infantile nystagmus, the range of optic nerve loss, and cognitive delay. This study examined visual evoked potential (VEP) responses and averaging techniques in children with ONH. The assumption is that EEG epochs with inconsistent temporal phase would be associated with nystagmus, signal reduction due to axon loss, and visual inattention. METHODS A retrospective chart review was performed on 44 children (average age 2.2 years; SD 1.9). Optic disc diameter was estimated by ophthalmoscopy. Visual function was measured under binocular viewing and then compared to the eye with the larger optic disc to exclude secondary amblyopia. Visual acuity was measured by Teller cards or by recognition optotypes, and both measures were converted into log minimum angle of resolution (logMAR). VEPs were recorded to onset/offset of horizontal gratings and to reversing checkerboards. Signal-to-noise ratios (SNRs) were estimated from phase consistency across epochs in the Fourier domain. VEPs were also averaged after (1) correction of epochs for phase shifts across a limited bandwidth, or (2) selection of only epochs showing phase consistency. RESULTS Optic disc diameter, logMAR, VEP amplitudes, and VEP SNR were all significantly inter-correlated. Optic disc diameter correlated best with VEP SNR (Spearman rho = 0.82; p < 0.001). Age-corrected logMAR correlated with optic disc diameter and VEP SNR (Spearman rho = -0.695 and 0.70, respectively; p < 0.001). VEP latency poorly correlated with optic disc diameter or logMAR. Correction of phase shifts or selection of epochs based on phase consistency significantly increased VEP amplitude and SNR for children with optic disc diameters <1000 microns. Correction of phase inconsistency did not improve the correlation of VEP parameters with optic disc diameter or with logMAR. CONCLUSIONS In ONH, the size of the optic nerve is correlated with VEP SNR and logMAR. The results imply a direct relationship between the reduction in optic nerve axons and generalized reduction in visual function. Our calculation of VEP SNR provides objective assessment of optic nerve function that is independent of subjective scoring of VEP peaks.
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Affiliation(s)
- John P Kelly
- Division of Ophthalmology, OA.5.345, Roger H. Johnson Vision Lab, Seattle Children's Hospital, 4800 Sand Point Way NE, Seattle, WA, 98105, USA. .,Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, 98105, USA.
| | - James O Phillips
- Division of Ophthalmology, OA.5.345, Roger H. Johnson Vision Lab, Seattle Children's Hospital, 4800 Sand Point Way NE, Seattle, WA, 98105, USA.,Department of Otolaryngology, University of Washington School of Medicine, Seattle, WA, USA
| | - Avery H Weiss
- Division of Ophthalmology, OA.5.345, Roger H. Johnson Vision Lab, Seattle Children's Hospital, 4800 Sand Point Way NE, Seattle, WA, 98105, USA.,Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, 98105, USA
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Kybartaite-Ziliene A, Gelzinis A, Krisciukaitis A. A method for reconstruction of visually evoked potentials from limited amount of sweeps. BIOMED ENG-BIOMED TE 2016; 61:579-586. [DOI: 10.1515/bmt-2015-0088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 11/09/2015] [Indexed: 11/15/2022]
Abstract
AbstractVisually evoked potentials (VEPs) are signals evoked by a visual stimulus. They consist of brief discrete deflections embedded in background electroencephalographic (EEG) activity, which often has larger amplitude. Background EEG cancelation is a major part of VEPs analysis algorithms often realized by coherent averaging or other methods requiring large minimal amount of registered sweeps. In some cases, especially for pediatric patients, or in poor patient compliance cases, long procedure duration and fatigue might cause impaired attention and non-steady target fixation, affecting the quality of recorded VEPs. The possibility to reconstruct VEPs in every single sweep from limited size ensembles opens new diagnostic possibilities and shortens the registration procedure improving its quality. A proposed method is based on truncated expansion (Karhunen-Loève transform) of VEP signals applying generalized universal basis functions (eigenvectors of covariation matrix) calculated from learning set of sweeps, i.e. an ensemble of collected typical recordings. It realizes the possibility to reconstruct a signal from every single sweep even in limited size ensembles of registered sweeps. Application of adaptively time-shifted basis functions enables optimal reconstruction of the signal with latency shift or jitter.
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Kelly JP, Tarczy-Hornoch K, Herlihy E, Weiss AH. Occlusion therapy improves phase-alignment of the cortical response in amblyopia. Vision Res 2015; 114:142-50. [DOI: 10.1016/j.visres.2014.11.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 11/10/2014] [Accepted: 11/17/2014] [Indexed: 10/24/2022]
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Lack of visual evoked potentials amplitude decrement during prolonged reversal and motion stimulation in migraineurs. Clin Neurophysiol 2014; 125:1223-30. [DOI: 10.1016/j.clinph.2013.10.050] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Revised: 10/11/2013] [Accepted: 10/30/2013] [Indexed: 01/09/2023]
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Aamand R, Ho YCL, Dalsgaard T, Roepstorff A, Lund TE. Dietary nitrate facilitates an acetazolamide-induced increase in cerebral blood flow during visual stimulation. J Appl Physiol (1985) 2013; 116:267-73. [PMID: 24336884 DOI: 10.1152/japplphysiol.00797.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The carbonic anhydrase (CA) inhibitor acetazolamide (AZ) is used routinely to estimate cerebrovascular reserve capacity in patients, as it reliably increases cerebral blood flow (CBF). However, the mechanism by which AZ accomplishes this CBF increase is not entirely understood. We recently discovered that CA can produce nitric oxide (NO) from nitrite, and that AZ enhances this NO production in vitro. In fact, this interaction between AZ and CA accounted for a large part of AZ's vasodilatory action, which fits well with the known vasodilatory potency of NO. The present study aimed to assess whether AZ acts similarly in vivo in the human cerebrovascular system. Hence, we increased or minimized the dietary intake of nitrate in 20 healthy male participants, showed them a full-field flickering dartboard, and measured their CBF response to this visual stimulus with arterial spin labeling. Doing so, we found a significant positive interaction between the dietary intake of nitrate and the CBF modulation afforded by AZ during visual stimulation. In addition, but contrary to studies conducted in elderly participants, we report no effect of nitrate intake on resting CBF in healthy human participants. The present study provides in vivo support for an enhancing effect of AZ on the NO production from nitrite catalyzed by CA in the cerebrovascular system. Furthermore, our results, in combination with the results of other groups, indicate that nitrate may have significant importance to vascular function when the cerebrovascular system is challenged by age or disease.
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Affiliation(s)
- Rasmus Aamand
- Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
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Kelly JP, Darvas F, Weiss AH. Waveform variance and latency jitter of the visual evoked potential in childhood. Doc Ophthalmol 2013; 128:1-12. [PMID: 24146335 DOI: 10.1007/s10633-013-9415-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 10/08/2013] [Indexed: 11/25/2022]
Abstract
PURPOSE Recording the visual evoked potential (VEP) in young children is challenging due to movement artifacts with variable fixation or attention. This study examined the effects of latency jitter, noise, and waveform consistency on the averaging of the VEP across childhood age. METHODS Stimuli were contrast-reversing (1.4 Hz) checkerboards of 163 arc minutes and pattern-onset-offset of 0.5 cycle/degree horizontal sine-wave gratings. Subjects were 79 normal children (0.3-16 years age; mean 6.9). Results were compared to recordings of EEG noise only (noise controls). Epochs underwent four averaging methods: (1) latency jitter correction using cross-correlation, (2) correction of phase shifts across a limited bandwidth in the Fourier domain, (3) selection of epochs based on consistency in the time domain, and (4) selection of epochs based on phase consistency in the Fourier domain. Signal-to-noise ratios (SNR) were estimated in both the time and Fourier domains. RESULTS Compared to standard averaging, all methods improved the amplitude of the primary peak (P100) while generating mild changes in latency. All methods also increased amplitudes of residual peaks in noise controls. In VEPs with an adequate SNR, selective averaging in the Fourier domain provided the greatest improvement in amplitude (61 % increase; p < 0.0001) without prolongation in latency. Correction of latency jitter did not consistently improve amplitude but caused latency prolongation in 24 % of subjects. There was no age-related effect of any averaging method for either stimulus. CONCLUSIONS Since latency jitter correction does not improve VEP amplitude more than selective averaging, recording artifacts in children are dominated by random phase components rather than inducing latency jitter.
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Affiliation(s)
- John P Kelly
- Division of Ophthalmology, OA.6.239, Roger H. Johnson Vision Lab, Seattle Children's Hospital, 4800 Sand Point Way NE, Seattle, WA, 98105, USA,
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