This study compared the variability of visual evoked potential (VEP) in response to stimulation of eyes affected by unilateral optic neuritis with that of fellow (non-affected) eyes. Pattern-reversal VEP (PVEP) and motion-onset VEP (MVEP) recordings from thirty-six subjects with unilateral optic neuritis at different intervals from disease onset were retrospectively evaluated, and differences in the following parameters were compared: signal‒to‒noise ratio (SRN), interquartile range of the response jitter (jitter IQR), and number of trials corresponding to the average response (corresponding N). In the PVEP recordings, the P1 peak times of the fellow eyes were significantly shorter than those of the affected eyes (Cohen’s d = -1.470, p < 0.001). P1 amplitudes were significantly greater in fellow eyes (d = 1.17, p < 0.001). Significant differences were found in the SNR (d = 0.782, p < 0.001), jitter IQR (d = -0.874, p < 0.001), and corresponding N (d = 0.700, p < 0.001). MVEP presented significantly shorter N2 peak times in fellow eyes than in affected eyes (d = 0.840, p < 0.01) and significantly greater amplitudes (d = 0.494, p = 0.002). There was a significant difference in the SNRs (d = 0.440, p = 0.01) and corresponding N values (d = 0.415, p = 0.01). There was no difference in the jitter IQR (d = 0.143, p = 0.230). The increased variability in eyes affected by optic neuritis compared with fellow eyes (in particular, in pattern-reversal VEP, which predominantly represents the activity of the macular–papillary fibers of the optic nerves) may represent important pathophysiologic features and may add valuable information to diagnostics via VEP examinations.

Purpose The aim of this neurophysiological study was to retrospectively analyze visual evoked potentials (VEPs) acquired during an examination for diagnosing optic nerve involvement in patients with Lyme neuroborreliosis (LNB). Attention was focused on LNB patients with peripheral facial palsy (PFP) and optic nerve involvement. Methods A total of 241 Czech patients were classified as having probable/definite LNB (193/48); of these, 57 were younger than 40 years, with a median age of 26.3 years, and 184 were older than 40 years, with a median age of 58.8 years. All patients underwent pattern-reversal (PVEP) and motion-onset (MVEP) VEP examinations. Results Abnormal VEP results were observed in 150/241 patients and were noted more often in patients over 40 years (p = 0.008). Muscle/joint problems and paresthesia were observed to be significantly more common in patients older than 40 years (p = 0.002, p = 0.030), in contrast to headache and decreased visual acuity, which were seen more often in patients younger than 40 years (p = 0.001, p = 0.033). Peripheral facial palsy was diagnosed in 26/241 LNB patients. Among patients with PFP, VEP peak times above the laboratory limit was observed in 22 (84.6%) individuals. Monitoring of patients with PFP and pathological VEP showed that the adjustment of visual system function occurred in half of the patients in one to more years, in contrast to faster recovery from peripheral facial palsy within months in most patients. Conclusion In LNB patients, VEP helps to increase sensitivity of an early diagnostic process.

Despite positive prior results obtained by using event-related potentials (ERPs) in psychiatric patients, they are not routinely used in the clinical setting. This may in part be due to problems regarding a lack of transportable equipment availability. It can be difficult for these patients to repeatedly visit electrophysiological laboratories. To address this issue, we propose using a new, fully portable device for visually evoked potentials (VEP) and cognitive function assessment, that can be used for quick examinations (https://www.veppeak.com). Our device, called "VEPpeak", is built into a headset with a color LED visual stimulator. It weighs 390 g and is connected to a notebook (PC) with evaluation software via USB. In this pilot study, we verified the device's usability in 31 patients with schizophrenia. We used the oddball paradigm with the recognition of colors for the P300 wave and choice reaction time evaluation. The examination lasted only about ten minutes. The results indicated good reproducibility of large cognitive potentials (P300) with prolonged P300 latencies and reduced amplitudes in patients compared to 15 control subjects. The P300 latency and reaction time prolongation in patients correlated with their age and the sedative effect of the pharmacotherapy.

Aim: Visual evoked potentials (VEP) represent an objective non-invasive and inexpensive dia-gnostic method, particularly in neuro-ophthalmology. A lot of possible dia gnostic applications are limited because they are only examined with the use of robust equipment which is hardly transportable and immobile and handicapped patients cannot visit the specialized labs. The aim of our research work was the development of a portable inexpensive VEP device that could be used almost anywhere. Methods: All parts of the last prototype of the device (built-in visual stimulator, recording electrodes, 4-channel EEG amplifier, analog-digital converter, and control unit) with a total weight of 390 g are placed in a headset (plastic "shield" with an adjustable strap). The software for VEP recording and evaluation is used on a standard notebook (PC). The parameters of the device fulfi ll recommendations of the international societies for clinical electrophysiology of vision and clinical neurophysiology also enabling new applications of so far not routinely used variants of evoked potentials. Testing of the device was done so far in 91 control subjects and 135 neuroophthalmological patients. Results: Pilot studies proved comparable parameters of VEP and dia gnostic sensitivity as in standard devices (equal results in 93% of cases). It was verified that the device is usable in various environments, at the patient's bedside, and also for basic self-examination. Conclusion: The portable device for VEP significantly increases the availability of their examination and thus enables much broader dia gnostic applications of this method.

We developed a new portable device called “VEPpeak” for the examination of visual evoked potentials (VEPs) to extend VEP examination beyond specialized electrophysiological laboratories and to simplify the use of this objective, noninvasive, and low-cost method for diagnostics of visual and central nervous system dysfunctions. VEPpeak consists of a plastic headset with a total weight of 390 g containing four EEG amplifiers, an A/D converter, a control unit, and a visual LED stimulator built in the front, vertically adjustable peak. The device is powered and controlled via USB connection from a standard PC/notebook using custom software for visual stimuli generation and for VEP recording and processing. Up to four electrodes can be placed at any scalp location or in combination with two dry electrodes incorporated into the headset. External visual stimulators, such as a tablet, can be used with synchronization. Feasibility and validation studies were conducted with 86 healthy subjects and 76 neuro-ophthalmological patients including 67 who were during the same session also tested with a conventional VEP system. VEPpeak recordings to standard (pattern-reversal) and non-standard (motion-onset, red-green alternation) were robust and repeatable and obtained also in immobilized patients. Good comparability of results was achieved between VEPpeak and standard examination. Some systematic differences in peak latencies and amplitudes are consistent with differences in stimulus characteristics of the two compared systems. VEPpeak provides an inexpensive system for clinical use requiring portability. In addition to ISCEV standard VEP protocols, free choice of stimuli and bio-signal recordings make the device universal for many electrophysiological purposes.

Background For patients with age-related macular degeneration (AMD), a special intraocular lens implantation partially compensates for the loss in the central part of the visual field. For six months, we evaluated changes in neurophysiological parameters in patients implanted with a “Scharioth macula lens” (SML; a center near high add + 10 D and peripheral plano carrier bifocal lens designed to be located between the iris and an artificial lens). Methods Fourteen patients (5 M, 9 F, 63–87 years) with dry AMD were examined prior to and at 3 days after, as well as 1, 2, and 6 months after, implantation using pattern-reversal, motion-onset, and cognitive evoked potentials, psychophysical tests evaluating distant and near visual acuity, and contrast sensitivity. Results Near visual acuity without an external aid was significantly better six months after implantation than before implantation (Jaeger table median (lower; upper quartile): 4 (1; 6) vs. 15 (13; 17)). Distant visual acuity was significantly altered between the pre- (0.7 (0.5; 0.8) logMAR) and last postimplantation visits (0.8 (0.7; 0.8) logMAR), which matched prolongation of the P100 peak time (147 (135; 151) ms vs. 161 (141; 166) ms) of 15 arc min pattern-reversal VEPs and N2 peak time (191.5 (186.5; 214.5) ms vs. 205 (187; 218) ms) of peripheral motion-onset VEPs. Conclusion SML implantation significantly improved near vision. We also observed a slight but significant decrease in distant and peripheral vision. The most efficient electrophysiological approach to test patients with SML was the peripheral motion-onset stimulation, which evoked repeatable and readable VEPs.

The aim of this neurophysiological study was to monitor changes in the visual and cognitive function of HIV-infected patients treated with combination antiretroviral therapy.

The aim of this introductory lecture is to point out that despite the intensive use of modern imagine techniques (MRI, OCT, etc.), the diagnostic applications of visual evoked potentials (VEPs) need not be obsolete, if not preferable in many cases. This objective, fully non-invasive, low-cost electrophysiological method can detect functional problems of the optic pathway and various brain cortical areas even before a development of the first displayable morphological changes. For the increased sensitivity of VEPs, it is necessary to use a larger spectrum of visual stimuli (activating quite selectively different subsystems of the visual pathway and visual cortex) compared to standards recommended by ISCEV or IFCN. It should include not only flash or pattern-related stimuli (pattern-reversal, pattern-on/off) but also motion-related (motion-onset VEPs) and cognitive visual stimulation. Then, not only the early diagnostics of a large spectrum of neuro-ophthalmological and neuro-psychiatric disorders is possible but also the physiological aging of visual information processing or a drug abuse is recognisable. For a better availability of VEPs examination and their long-term monitoring also in home conditions, we have just introduced a “Mobile (wearable), low-cost device for examination of visual evoked potentials (VEPs)”, the use of which will be demonstrated during the lecture. Acknowledgements: Supported by the project of Charles University “Progres Q40/07”.

The goal of the current study was to explore visual function in virally suppressed HIV patients undergoing combined antiretroviral therapy (cART) by using pattern-reversal and motion-onset visual evoked potentials (VEPs).

Standard pattern-reversal visual evoked potentials (VEPs) and motion-onset VEPs (M-VEPs) were tested in 19 dyslexics and 19 normal readers aged 7-13 years in order to evaluate the feasibility of M-VEPs for the objective diagnostics of a visual subtype of dyslexia, in which a dysfunction of the magnocellular subsystem/dorsal stream of the visual pathway is suspected. The set of VEPs consisted of the pattern-reversal VEPs with check sizes of 20', two types of translational motion (with low and high contrast) and two types of radial motion (in the full field or the periphery). While the P100 peak parameters in pattern-reversal VEPs did not differ between the group of dyslexics and controls, the group of dyslexics displayed significantly longer N2 latencies in all types of M-VEPs. Abnormal N2 latencies were found in 35-56% of dyslexics in different types of M-VEPs, with translational motion with high contrast being the most sensitive stimulation. A receiver operating characteristic analysis showed that the latencies of M-VEPs displayed higher discrimination potential than M-VEPs amplitudes. The study confirms a "magnocellular pathway/dorsal stream deficit" in approximately half of dyslexics.

Recording of the visual mismatch negativity (vMMN) requires building of a visual temporal regularity using standard stimuli and afterwards interrupting of such regularity by a deviant stimulus. However, for the veridical vMMN it is necessary to control subject's attention by a task, because the attentional modulation might elicit a similar event related response (ERP) as the vMMN. In this contribution we point out an important and unexpected interaction between the attentional task and the regularity violation. We presented standard/deviant stimuli (a moving grating) in periphery of the visual field and targets/non-targets (numbers) stimuli in the central part of the visual field. Targets were presented randomly with preceding 2, 3 or 4 non-target stimuli (so the time between targets was randomly selected in the interval of 2460–4100 ms. Subjects (aged 21–61 years, 3 females) pressed a button when they spot the target. To make the recording session as short as possible the target was presented immediately (400 ms) after each deviant; this way deviants were unpredictable and also uninterrupted by a slow response to the target. ERPs were recorded from 68 unipolar electrodes, (four EOG channels) with the right earlobe as a reference. In results we observed a statistically significant vMMN-like response in the interval of 150–250 ms. This response, however, exhibited unexpected features, as its localisation was in the central area with prevalence to the left hemisphere (all subjects responded by the right hand) and it was absent in recordings where the subjects' response was not required. Further, we observed difference in a linear trend of the ERPs to standard/deviant stimuli. All these signs supported evidence that the vMMN-like potential was a false vMMN created by superposition of a preparatory potential for the target detection (the early readiness potential – Bereitschafts Potential) and the deviant response. The presented stimulation scheme with a randomised appearance of the deviant stimulus and the attentional task caused the false vMMN because the subjects' expectation of the target stimulus resulted in the readiness potential, which precedes the behavioural response even couple of seconds before subjects' reaction. Due to a suboptimal design, this preceding response was superimposed in a greater extent over the deviant response than over the standard one. The linear character of the readiness potential, however, allows its extraction from the ERP and identification of the veridical vMMN (Kremláček, 2013). Supported by P37/07 (PRVOUK) program of Charles University.

In adults, motion-onset visual evoked potentials (M-VEPs) with a dominant N2 peak represent a useful diagnostic tool. However, it is difficult to use this type of VEP in children because of the long maturation (up to 18 years) of M-VEPs, which is characterised by a gradual decrease in N2 peak latency and shape development. Moreover, in some children, M-VEPs are difficult to identify with standard stimuli.

Introduction In our previous papers (for review see Kuba et al., Vision Res., 2007, 47, 189–202) we have shown that in adults the motion-onset visual evoked potentials (M-VEPs) represent a useful diagnostic tool in neuro-opthalmology because they enable to test quite selectively the magnocellular system/dorsal stream function. In adults robust M-VEPs with low variability and typical shape with dominant negative N160 peak can be acquired easily, however, it is difficult to record and evaluate this type of VEPs in children. The M-VEPs go through very long maturation (up to 18 years of age) accompanied by gradual shortening of main negative peak latencies and also by age dependent shape development (Langrova et al., Vision Res., 2006, 46, 536–544). Moreover, they are unidentifiable to standard moving stimuli in some children. To understand better this problem, we tested 30 normal children aged 7–12 years. Methods We performed the set of standard stimuli used in our lab (https://www.lfhk.cuni.cz/elf) for examination of adults – low contrast translation motion (TM) and expansion/contraction motion (EXCOM). Results Reliable VEPs were detected in 77% of children to TM and in 83% of children to EXCOM. The dominant peak of the VEPs was negative in all TM VEPs and in 80% of EXCOM VEPs (positive in 20%). In both VEP types there was large inter-individual latency variability (in the range of 176–268 ms in TM and 176–290 ms in EXCOM). When a high contrast TM stimulus (non-optimal “magno” stimulus) was used, the M-VEP latencies shortened and amplitudes increased in majority of subjects. In contrast to adults, M-VEPs to peripheral stimulation (outside central 20°) were detectable only in 43% of children. Conclusions Our findings show that maturation of motion perception in children is rather inter-individually variable, which makes a diagnostic use of M-VEPs in children quite complicated. Acknowledgement Supported by the project PRVOUK - P37/07.

At present, predominantly stationary visual stimulators are used for diagnostic examination of visual evoked potentials (VEPs). They cover significantly the central visual field of the tested subject and such examination does not allow any other parallel activity during the stimulation. Therefore, it cannot be used e.g. for a long-term monitoring and evaluation of functional changes of CNS functions – for continual assessment of visual perception. We have introduced a visual stimulator (Czech Republic patent No. 303192 pending), the principle of which is that the source of light stimuli is in periphery of the visual field – a row of light emitting diodes (LEDs) is placed on the head of a stimulated subject on a standard peak (a part of a baseball cap). A control unit switches individual LEDs (flash or motion stimuli are generated) and synchronizes VEPs evaluation. The set of LEDs is located about 20° from the center of the stimulus field. There are several variants of stimulation available because of significant inter-individual differences in reactivity of subjects to particular stimuli. The motion stimuli have similar parameters as stimulations used for clinical diagnostic purposes (see Kuba, M., Kubová, Z., Kremláček, J., et al. Motion-onset VEPs: Characteristics, methods, and diagnostic use. Vision Res., 2007, vol. 47, p. 189–202 – http://dx.doi.org/10.1016/j.visres.2006.09.020). Recording of VEPs (with the use of built-in amplifiers) and on-line evaluation of their parameter changes can be done via “blue-tooth” transmission to a standard computer or in a built-in microprocessor (in preparation). Since using of this kind of VEPs examination does not interfere with common human activities, it is possible to use it not only for standard diagnostic purposes in neuro-ophthalmological diseases but also for monitoring of CNS function changes or level of vigilance/fatigue, e.g. in drivers or some other professions. Supported by EU project CZ.1.05/3.1.00/13.0284 and by Charles University project PRVOUK P37/07.

The manipulation of attention can produce mismatch negativity-like components that are not necessarily connected to the unintentional sensory registration of the violation of probability-based regularity.For clinical purposes, attentional bias should be quantified because it can vary substantially among subjects and can decrease the specificity of the examination.This experiment targets the role of attention in the generation of visual mismatch negativity (vMMN).The visual regularity was generated by a sequence of two radial motions while subjects focused on visual tasks in the central part of the display.Attentional load was systematically varied and had three levels, no-load, easy, and difficult.Rare, deviant, and frequent standard motions were presented with a 10/60 ratio in oddball sequences.Data from 12 subjects was recorded from 64 channels and processed.vMMN was identified within the interval of 142-198 ms.The mean amplitude was evaluated during the aforementioned interval in the parietal and fronto-central regions.A general linear model for repeated measures was applied to the mean amplitude with a three-factor design and showed a significant difference [F (1, 11) = 17.40, p = 0.002] between standard and deviant stimuli and between regions [F (1, 11) = 8.40, p = 0.01]; however, no significant effect of the task [F (2, 22) = 1.26, p = 0.30] was observed.The unintentional detection of irregularity during the processing of the visual motion was independent of the attentional load associated with handling the central visual task.The experiment did not demonstrate an effect of attentional load manipulation on mismatch negativity (MMN) induced by the motion-sequence, which supports the clinical utility of this examination.However, used stimulation paradigm should be further optimized to generate mismatch negativity that is stable enough to be usable not only for group comparisons but also for a single subject assessment.

Purpose Despite quite a long history of visual evoked potentials (VEPs), their use has been limited so far almost exclusively to flash or pattern related responses of the primary visual cortex (mediated mainly via activation of the parvocellular system of the visual pathway. It is surprising that efforts to extend it to more complex testing including an examination of the motion processing system (magnocellular system and dorsal stream) are quite rare (e.g. Kuba and Kubová, Doc Ophthalmol, 1992, 80, 83-89; Kubová et al., 1995, Vision Res, 35, 197-205. Methods Early or selective involvement of the motion processing system is suspected in many CNS disorders and we suggest that motion-onset VEPs may recognize functional problems of this kind better than imagine techniques (Kuba et al., Vision Res, 2007, 47, 189-202. Results Motion-onset VEPs display latency shortening up to the age of about 18 years representing very slow individually different maturation of the motion processing system (Langrova et al., Vision Res., 2006, 46, 536-544. In early adulthood they start accelerated latency prolongation when compared to pattern-reversal, which might be a good indicator of individual biological ageing (Kuba et al., Vision Res, 2012, 62, 9-16. Conclusion Since about 30% of pathological findings in our parallel pattern-reversal and motion-onset VEPs examinations in neuro-ophthalmological patients display exclusively the motion-onset VEPs pathology, we strongly recommend using them both in the theoretical vision research and ophthalmological diagnostics. Acknowledgement: Supported by the project PRVOUK - P37/07.

Purpose In adults the motion-onset visual evoked potentials (M-VEPs) represent a useful diagnostic tool in neuro-opthalmology (Kuba et al.,Vision Res., 2007, 47, 189-202) since they test quite selectively the magnocellular system/dorsal stream function. Whilst in adults robust M-VEPs with low variability can be acquired easily, it is difficult to record and evaluate them in children. They not only display very long maturation and age dependent shape development (Langrova et al., Vision Res., 2006, 46, 536-544) but in some children they are unidentifiable to standard stimuli. Methods To understand better this problem we tested 30 normal children aged 7 - 12 years. Two types of motion stimuli were used – translation motion (TM) and expansion/contraction motion (EXCOM). Results Reliable VEPs were detected in 77% of children to TM and in 83% of children to EXCOM. The dominant peak of the VEPs was negative in all TM VEPs and in 80 % of EXCOM VEPs (positive in 20%). In both VEP variants the latency of the negative peak did not shorten significantly in the tested age range and there was large interindividual latency variability (176 ms – 268 ms). High contrast stimuli (non-optimal “magno” stimulus) shortened the M-VEPs latencies and enlarged amplitudes in majority of subjects. M-VEPs to peripheral stimulation (outside central 20°) were in contrast to adults detectable only in 43 % of children. Conclusion These findings show distinct differences in maturation of motion perception in children, which makes a diagnostic use of M-VEPs in children quite complicated. Acknowledgement: Supported by the project PRVOUK - P37/07.