Visual Evoked Potentials Amplitude Research Articles

Interaction of Sensitivity, Emotions, and Motivations During Visual Perception.

When an organism is exposed to environmental stimuli of varying intensity, the adaptive changes in the CNS can be explained by several conceptual provisions: the law of motivation-activation by Yerkes and Dodson, the laws of force and pessimal protective inhibition, and the theory of emotion activation. Later, reinforcement sensitivity theory was developed in the fields of psychology and psychophysics. At the same time, cortical prepulse inhibition (PPI), the prepulse inhibition of perceived stimulus intensity (PPIPSI), and the augmentation/reduction phenomenon were proposed in sensory neurophysiology, which expanded our understanding of consciousness. The aim of this study was to identify markers of levels of activity of cognitive processes under normal and in psychopathological conditions while amplifying the information stimulus. For this purpose, we changed the contrast level of reversible checkerboard patterns and mapped the visual evoked potentials (VEPs) in 19 monopolar channels among 52 healthy subjects and 39 patients with a mental illness without an active productive pathology. Their cognitive functions were assessed by presenting visual tests to assess invariant pattern recognition, short-term visual memory, and Gestalt perception. The personalities of the healthy subjects were assessed according to Cattell's 16-factor questionnaire, linking the data from neurophysiological and cognitive studies to factors Q4 (relaxation/tension) and C (emotional stability). According to the N70 and N150 VEP waves, the healthy subjects and the patients were divided into two groups. In some, there was a direct relationship between VEP amplitude and contrast intensity (21 patients and 29 healthy persons), while in the others, there was an inverse relationship, with a reduction in VEP amplitude (18 patients and 23 healthy persons). The relationship and mechanisms of subjects' cognitive abilities and personality traits are discussed based on the data acquired from the responses to information stimuli of varied intensity.

Relevance of optic nerve B-mode sonography in multiple sclerosis diagnosis and follow-up

BackgroundAmong young people, multiple sclerosis (MS) accounts for the majority of non-traumatic neurological impairments. Almost all MS patients develop optic neuritis as the illness progresses. In MS, the optic nerve (ON) is vulnerable to demyelinating injury and is considered “eloquent” in comparison with the brain. Thus, it serves as a clinical model for MS. Since the eye is a suitable target for ultrasonography due to its high-water content, non-invasive trans-orbital sonography (TOS) can determine the optic nerve sheath diameter (ONSD). This research aimed to determine the effectiveness of ON ultrasonography as a simple, low-cost method for diagnosing and following up MS patients, facilitating their treatment plan. It correlates the findings of ONSD using TOS and visual-evoked potential (VEP), the number of magnetic resonance imaging (MRI) black holes, and other clinically significant parameters in 30 relapsing–remitting MS (RRMS) patients versus 30 controls.ResultsWe examined a total of 120 eyes. The ONSD values at 3 mm, 5 mm, and myelination index were significantly lower in the patients (4.7 ± 0.3, 5.5 ± 0.3, and 0.86 ± 0.03, respectively) versus the controls (5.6 ± 0.3, 6.2 ± 0.4, and 0.90 ± 0.03, respectively) (p < 0.001 in each). The mean P 100 latency was significantly delayed in the patients (125.5 ± 6.1 ms) than the controls (100.2 ± 3.3 ms), (p < 0.001). The mean VEP amplitude was significantly lower in the patients (4.9 ± 0.7 μV) than the controls (6.8 ± 0.8 μV) (p < 0.001). There was a highly significant positive correlation between the ONSD and P 100 amplitude, and highly significant negative correlations between the ONSD and disease duration, number of optic neuritis attacks, EDSS, MRI black holes number, and P 100 latency.ConclusionsTrans-orbital sonography is a practical and easily accessible approach for assessing ON atrophy in MS. It can measure axonal loss and brain atrophy indirectly and is a reliable paraclinical diagnostic tool, suggesting that ONSD could be a biomarker of disease activity.

Role of Visual Evoked Potential and Ocular Trauma Score as Predictors of Visual Recovery in Eye Globe Injuries.

Evaluate visual evoked potential (VEP) and ocular trauma score (OTS) efficacy in predicting visual potential in globe trauma without optic nerve involvement. A retrospective cohort study analyzed clinical data from eye globe injury cases undergoing flash VEP between January 2000 and May 2021. Inclusion criteria: flash VEP completion within 48 hours, pre-surgical intervention. Exclusions: head trauma, optic nerve injuries. Abnormal VEP: <7 µV amplitudes, >120ms latencies. The OTS was computed, and penetrating injuries were categorized. Of 85 eyes meeting the criteria (mean age: 31.9±20.6 years, 82.4% male), the median follow-up was 22 months. OTS directly correlated with the amount of Early Treatment Diabetic Retinopathy Study letters gained at follow-up and was inversely correlated with ocular penetration extent, and VEP signal amplitude. VEP amplitude is inversely correlated with maintaining/improving visual acuity. Positive predictive value for normal VEP predicting maintained/improved visual acuity: 75.6%, negative predictive value: 21.3%. In blunt trauma, baseline VEP amplitude had superior predictive value compared to penetrating injury. This study highlights a correlation between VEP signal amplitude and OTS with visual outcomes in traumatic eye injuries without optic nerve involvement. OTS emerges as a reliable VEP substitute, particularly in blunt trauma cases, where baseline VEP amplitude predicts visual recovery more accurately than penetrating injuries.

Decoding Visual Responses: Insights into Chronic Migraine and Medication Overuse Headache with Electrophysiological Analysis.

Background/Objectives: Habituation and sensitization are opposite phenomena that play a role in the pathophysiology of episodic migraine and its progression to chronic migraine (CM). There have been just a few studies that have investigated these phenomena in patients with medication overuse headache (MOH) in comparison to those with chronic migraine (CM) and healthy controls (HCs), and the findings have been inconsistent. Methods: We measured and examined visual evoked potentials (VEPs) in 81 patients with MOH and 24 patients with CM, as well as 24 HCs. The VEPs were used to assess sensitization by analysing the amplitude of the first block (100 sweeps) and to evaluate habituation by measuring the amplitude response decrement after six blocks. We further examined patients diagnosed with MOH based on their acute medication type and after a 3-week acute medication withdrawal program. Results: There were no significant differences between groups in terms of the first N1-P1 VEP amplitude block and its habituation. It was found that patients with MOH had a greater drop in the amplitude of the VEP P1-N2 complex after repeated stimulation than patients with CM or HC. The VEP parameters showed no significant differences based on the specific overused drug and after a 3-week acute medication withdrawal. Conclusions: We propose that the results obtained in patients with MOH indicate an abnormal activation of inhibitory circuits in the parieto-occipital region in response to repeated modulatory stimuli.

Investigating causal effects of pupil size on visual discrimination and visually evoked potentials in an optotype discrimination task.

Pupil size primarily changes to regulate the amount of light entering the retina, optimizing the balance between visual acuity and sensitivity for effective visual processing. However, research directly examining the relationship between pupil size and visual processing has been limited. While a few studies have recorded pupil size and EEG signals to investigate the role of pupil size in visual processing, these studies have predominantly focused on the domain of visual sensitivity. Causal effects of pupil size on visual acuity, therefore, remain poorly understood. By manipulating peripheral background luminance levels and target stimulus contrast while simultaneously recording pupillometry and EEG signals, we examined how absolute pupil size affects visual discrimination and visually evoked potentials (VEP) in a task using optotype mimicking the Snellen eye chart, the most common assessment of visual acuity. Our findings indicate that both higher background luminance levels and higher target contrast were associated with improved target discrimination and faster correct reaction times. Moreover, while higher contrast visual stimuli evoked larger VEPs, the effects of pupil size on VEPs were not significant. Additionally, we did not observe inter-individual correlations between absolute pupil size and discrimination performance or VEP amplitude. Together, our results demonstrate that absolute pupil size, regulated by global luminance level, played a functional role in enhancing visual discrimination performance in an optotype discrimination task. The differential VEP effects of pupil size compared to those of stimulus contrast further suggested distinct neural mechanisms involved in facilitating visual acuity under small pupils.

Comparison of Visual Evoked Potential Latency and Amplitude Values According to Visual Acuity among Normal Adult Eyes in dr. Cipto Mangunkusumo Hospital

Visual Evoked Potential (VEP) is a diagnostic procedure to evaluate pathological conditions affecting the visual pathway with several protocols, including pattern onset/offset VEP, flash VEP, and pattern-reversal VEP (PRVEP), standardized by International Society For Clinical Electrophysiology In Vision (ISCEV). PRVEP, the most common protocol used in clinical practice, is not always directly proportional to visual acuity (VA). Clarity of the refractory media and gender are presumed to affect it; thus, using PRVEP reference value based on refractory status is not casually applicable when the VA does not resemble refractory status. This study aims to determine the changes in VEP latency and amplitude value according to various subjective VA, and to examine and analyze these latency and amplitude values within male and female subject groups. The research was conducted at the Department of Ophthalmology, dr. Cipto Mangunkusumo Hospital from August to October 2017. Latency and amplitude values were measured with PRVEP. Measurement was performed on normal VA and defocus-induced VA to 6/18, 6/30, and 6/60 values, using small and large-sized checkerboard stimuli. Prolonged latency and decreased amplitude were found in male and female subject groups, corresponding with decreasing VA levels. Using 18 min arc and 48 min arc-sized checkerboards gave the closest result to the reference value. The difference in VEP value according to subjects' gender was found in amplitude but not in latency.

Comparison of Visual Evoked Potential Latency and Amplitude Values According to Visual Acuity among Normal Adult Eyes in dr. Cipto Mangunkusumo Hospital

Visual Evoked Potential (VEP) is a diagnostic procedure to evaluate pathological conditions affecting the visual pathway with several protocols, including pattern onset/offset VEP, flash VEP, and pattern-reversal VEP (PRVEP), standardized by International Society For Clinical Electrophysiology In Vision (ISCEV). PRVEP, the most common protocol used in clinical practice, is not always directly proportional to visual acuity (VA). Clarity of the refractory media and gender are presumed to affect it; thus, using PRVEP reference value based on refractory status is not casually applicable when the VA does not resemble refractory status. This study aims to determine the changes in VEP latency and amplitude value according to various subjective VA, and to examine and analyze these latency and amplitude values within male and female subject groups. The research was conducted at the Department of Ophthalmology, dr. Cipto Mangunkusumo Hospital from August to October 2017. Latency and amplitude values were measured with PRVEP. Measurement was performed on normal VA and defocus-induced VA to 6/18, 6/30, and 6/60 values, using small and large-sized checkerboard stimuli. Prolonged latency and decreased amplitude were found in male and female subject groups, corresponding with decreasing VA levels. Using 18 min arc and 48 min arc-sized checkerboards gave the closest result to the reference value. The difference in VEP value according to subjects' gender was found in amplitude but not in latency.

Efficacy of intraoperative visual evoked potential amplitude reduction in predicting visual outcome after extended endoscopic endonasal resection of craniopharyngiomas.

Postoperative visual outcome is a major concern of neurosurgeons for patients with craniopharyngiomas. The current study aimed to investigate the value of visual evoked potential (VEP) amplitude reduction (N75-P100 and P100-N145) for predicting postoperative visual dysfunction (POVD) and refining current warning criteria for VEP monitoring. Data from 96 patients who underwent the extended endoscopic endonasal approach for craniopharyngiomas between October 2020 and November 2021 were retrospectively reviewed. VEP amplitude reduction ratios were calculated and compared between patients with POVD and those without. Subsequently, the critical threshold values of VEP amplitude reduction ratios for predicting POVD were obtained through receiver operating characteristic curve analysis. Finally, multivariate binary logistic regression analysis was applied to evaluate the effect of potential factors on the probability of experiencing POVD. Both N75-P100 and P100-N145 amplitude reduction ratios were significantly higher in patients with POVD (p < 0.001 for both). The threshold value of the N75-P100 amplitude reduction ratio for predicting POVD was 51.76% with an area under the curve (AUC) of 0.816 (p < 0.001), while the threshold value of the P100-N145 amplitude reduction ratio was 38.80% with an AUC of 0.738 (p < 0.001). Both N75-P100 and P100-N145 amplitude reduction ratios were identified as independent predictors for POVD via multivariate analysis (p < 0.001 and p = 0.018, respectively). Both N75-P100 and P100-N145 amplitude reduction ratios showed great potential to be indicators for POVD in patients with craniopharyngiomas. Regarding warning criteria for VEP monitoring, the authors recommend that both N75-P100 and P100-N145 amplitude reduction should be considered, with early warning criteria of a 50% reduction for N75-P100 amplitude and/or a 40% reduction for P100-N145 amplitude.

Psychophysical, electrofunctional, and morphological evaluation in naïve neovascular AMD patients treated with intravitreal anti-VEGF.

The aim of this study was to investigate the retinal morpho-functional characteristics of patients with neovascular wet age-related macular degeneration (nAMD) treated with intravitreal injection (IV) of aflibercept (AFL). The study was conducted on 35 patients previously diagnosed with type 1 nAMD who received a fixed-dosing regimen of aflibercept injections over 12 months. The goal was to assess trends in visual abilities over time by measuring visual acuity (VA), contrast sensitivity (CS), visual evoked potentials (VEPs), and spectral domain-optical coherence tomography (SD-OCT). The same psychophysical, electro-functional, and morphological tests administered at baseline (T0) were repeated 4 to 8 weeks after the last aflibercept injection (Tn), resulting in a total of six examinations. At Tn, all subjects exhibited improved VA for both far and near distances compared to values detected at T0. Similarly, VEP amplitude and latency values at Tn showed a greater P100 improvement than those observed at T0. Additionally, the CS examination at Tn demonstrated improvement, particularly at high spatial stimulation frequencies. The Tn SD-OCT results highlighted a reduction in macular thickness compared to T0 values. This exploratory research indicates that intravitreal injections of AFL, following a fixed-dosing regimen, represent a valuable therapeutic approach for enhancing visual performance. This conclusion is supported by comprehensive statistical analysis of psychophysical, electro-functional, and morphological examinations within the same group of patients with nAMD, as demonstrated for the first time.

The clinical efficacy of preoperative flash visual evoked potential (VEP) for mature cataracts without a response to pattern VEP.

This study aims to assess the effectiveness of the preoperative flash visual evoked potential (VEP) test in predicting postoperative visual acuity for monocular mature cataract cases when compared to the contralateral normal eye. The study included 60 patients, each with a monocular mature cataract diagnosis, who underwent preoperative flash VEP testing showing no pattern VEP response. Subsequently, phacoemulsification was performed. The relationship between the flash VEP test latency values (P1, N2, P2) and amplitude value (N2-P2), and the degree of visual acuity recovery 3 months post-cataract surgery, was evaluated using the LogMAR scale. Furthermore, a linear regression analysis was conducted to explore the connection between preoperative flash VEP components and postoperative visual acuity. The average age of the patients was 65.4 ± 13.6 years, with a range of 43 to 87 years. The study included 36 males and 24 females. A significant disparity in visual acuity was observed between the preoperative and 3-month postoperative stages (p < 0.001). The preoperative flash VEP test for mature cataracts revealed significant delays in P1, N2, and P2 latency, as well as a reduction in N2-P2 amplitude potential when compared to the contralateral normal eye (p < 0.001). Notably, delayed P2 latency and reduced N2-P2 amplitude potential were particularly indicative of poor visual acuity prognosis after cataract surgery in the multiple regression analysis (p < 0.05). The N2-P2 amplitude potential was the important value that exhibited statistically significant results, with an area under the curve (AUC) of 80% sensitivity and 88% specificity, using a cutoff value of 6.07 μV. In cases of monocular mature cataract, a reduction in N2-P2 amplitude potential compared to the contralateral normal eye emerged as the most reliable predictor of postoperative visual prognosis following cataract surgery.

Knocking out the LRRK2 gene increases sensitivity to wavelength information in rats

Leucine-rich repeat kinase 2 (LRRK2) is a gene related to familial Parkinson’s disease (PD). It has been associated with nonmotor symptoms such as disturbances in the visual system affecting colour discrimination and contrast sensitivity. This study examined how deficiency of LRRK2 impacts visual processing in adult rats. Additionally, we investigated whether these changes can be modelled in wild-type rats by administering the LRRK2 inhibitor PFE360. Visual evoked potentials (VEPs) and steady-state visual evoked potentials (SSVEPs) were recorded in the visual cortex and superior colliculus of female LRRK2-knockout and wild-type rats to study how the innate absence of LRRK2 changes visual processing. Exposing the animals to stimulation at five different wavelengths revealed an interaction between genotype and the response to stimulation at different wavelengths. Differences in VEP amplitudes and latencies were robust and barely impacted by the presence of the LRRK2 inhibitor PFE360, suggesting a developmental effect. Taken together, these results indicate that alterations in visual processing were related to developmental deficiency of LRRK2 and not acute deficiency of LRRK2, indicating a role of LRRK2 in the functional development of the visual system and synaptic transmission.

The Effect of Ethambutol Therapy in terms of Visual Evoked Potential, Color Vision Test, and Contrast Sensitivity Test at the Subclinical Level

Abstract&#x0D; Introduction &amp; Objectives : Ethambutol is one of the first-line drugs in the treatment of tuberculosis and known to induce optic neuropathy. However, there are unknown protocols for detecting subclinical level of toxicity. The aim of this study was to assess the difference in amplitude and latency of visual evoked potential (VEP), color vision, and contrast sensitivity in tuberculosis patients before and after taking ethambutol for 1 and 2 months.&#x0D; Methods : This was a prospective observational cohort study of 38 eyes of 19 newly diagnosed patients with category-1 tuberculosis being treated with ethambutol. All patients were given ethambutol for 2 months at a dose of 15 - 20 mg/kg body weight/day. The participants underwent complete eye and visual function examination including pattern-reversal VEP, color vision with Farnsworth Munsell D-15 test, and contrast sensitivity with LEA Low Contrast Flip Chart before and after 1 and 2 months of treatment. Wilcoxon test was employed for data analysis.&#x0D; Results : During the study, no changes in visual acuity was observed. The results showed that the latencies of VEP after 1 month (p = 0.000) and 2 months (p = 0.000) of treatment were significantly delayed. There was a significant difference in contrast sensitivity after 2 months (p = 0.014) of treatment. However, no significant difference was found in color vision and amplitude of VEP.&#x0D; Conclusion : Latency of VEP and contrast sensitivity test could prove useful in detecting subclinical and hence very useful for monitoring patients under ethambutol therapy for ocular toxicity.

Gender differences and correlates of visual evoked potential parameters with head circumference: A comparative analysis

Background: Evoked potentials are electrical events recorded in the cerebral cortex after stimulation of a sense organ. They are non-invasive studies used to assess visual conduction pathways through optic nerves and the brain. Visual evoked potentials (VEPs) are affected by physiological factors such as age, sex, visual acuity, head circumference, and pupillary size. VEPs are used to diagnose and assess retinal pathology in ophthalmology, neurological pathology affecting the optic nerve and/or brain. Aims and Objectives: The aim of the study was to investigate gender-related alteration in parameters of VEP, to obtain relationship between head circumference with latency and amplitude values of VEP parameters. To investigate whether gender, head size, or both considered as an important factor influencing VEPs parameters. Materials and Methods: A cross-sectional study among 50 participants aged 19–29 with normal visual acuity and VEP recordings such as latencies and peak amplitude was performed using a RMS EMG EP Mark II machine. Results: The study examined the mean latencies for N75, P100, and N145 in the left and right eyes of 25 female and male participants. No significant differences were found in N75, P100, and N145 latencies between genders. However, females showed slightly higher amplitude differences than males. In the right eye, females showed higher N75 latency and P100 latency, but no significant gender differences were found for P100 latency or N145 latency. The Pearson correlation coefficient showed weak correlations between head circumference and VEP parameters for females and males, while no significant correlations were observed for females. Conclusion: VEPs are sensitive tools for evaluating visual conduction pathways in eye disease patients. However, gender differences in VEP parameters were not significant in this study, and a negative correlation was found between head size and VEP amplitude.

An analytical longitudinal observational study on the association of Vitamin D insufficiency in subjects with primary (idiopathic) demyelinating optic neuritis using visual evoked potential and optical coherence tomography

Background: Optic neuritis (ON) is an acute and often immune-mediated inflammatory condition of the optic nerve. Vitamin D acts as an anti-inflammatory agent and may confer neuroprotection. Visual evoked potential (VEP) and optical coherence tomography (OCT) are emerging tools for demyelinating diseases. Aims and Objectives: We tried to correlate between Vitamin D insufficiency and acute demyelinating ON using different parameters such as VEP, ganglion cell layer (GCL) thickness, and retinal nerve fiber layer (RNFL) thickness. Materials and Methods: This observational longitudinal analytical study included thirty non-consecutive patients with primary ON and 30 healthy controls. All patients with ON underwent detailed clinical and ophthalmological examination, and detailed blood workup, including serum 25 (OH) Vitamin D. VEP P100 latency, amplitude, OCT, RNFL thickness, and GCL thickness at presentation and after 3 months from May 2019 to November 2020. Results: Vitamin D insufficiency (below 30 ng/mL) was present in 60% of cases of ON. The baseline VEP showed significantly prolonged P100 latency in affected eyes in the Vitamin D insufficient group (mean 129.78±7.97 ms vs. 121.0±4.99 ms) whereas the P100 amplitude was not significantly altered between the two groups (5.5±3.13 μV vs. 7.08±3.01 μV). The baseline RNFL thickness (132.21±10.69 μm vs. 118.01±10.4 μm) and GCL thickness (76.82±2.04 μm vs. 73.06±3.2 μm) were greater in affected eyes of vitamin D insufficiency ON. There was greater RNFL thinning (79.93±3.42 μm vs. 74.80±3.5 μm) and GCL thinning (64.78±1.9μm vs. 69.02±2.22 μm) in affected eyes of ON with Vitamin D insufficiency at 3 months. Conclusion: Vitamin D insufficiency was found in most cases of ON. Insufficient Vitamin D positively correlated with optic nerve affection severity as evidenced by significantly increased baseline thickness of RNFL and GCL and more thinning of RNFL and GCL at the end of 3 months of follow-up.

Eyetracking-enhanced VEP for nystagmus

Visual evoked potentials (VEPs) are an important prognostic indicator of visual ability in patients with nystagmus. However, VEP testing requires stable fixation, which is impossible with nystagmus. Fixation instability reduces VEP amplitude, and VEP reliability is therefore low in this important patient group. We investigated whether VEP amplitude can be increased using an eye tracker by triggering acquisition only during slow periods of the waveform. Data were collected from 10 individuals with early-onset nystagmus. VEP was obtained under continuous (standard) acquisition, or triggered during periods of low eye velocity, as detected by an eye tracker. VEP amplitude was compared using Bonferroni corrected paired samples t-tests. VEP amplitude is significantly increased when triggered during low eye velocity (95% CI 1.42–6.83 µV, t(15) = 3.25, p = 0.0053). This study provides proof-of-concept that VEP amplitude (and therefore prognostic reliability) can be increased in patients with early onset nystagmus by connecting an eye tracker and triggering acquisition during periods of lower eye velocity.

Combination among VEP, OCT and TCD data in patients with relapsing-remitting multiple sclerosis during attack-free period

Aims Multiple sclerosis (MS) is characterized by inflammation, demyelination, glial cell pathology and axonal injury in the central nervous system, and also progressive axonal loss of the optic nerve in cases with optic neuritis (ON). The previous transcranial Doppler (TCD) investigations suggest cortical hyperreactivity in patients with relapsing-remitting Multiple sclerosis (RRMS). We investigated the effect of ON involvement on visual reactivity. Material and methods One hundred thirty patients with RRMS during attack-free period and 12 healthy subjects were enrolled to the study. Visual evoked potential (VEP), optic coherence tomography (OCT) and TCD examinations of all subjects were performed. Results Cerebrovascular reactivity measured with breath holding (BH) test was found to be normal. VEP amplitude, visual reactivity and peripapillary retinal nerve fibre layer (pRNFL) measurements were found to be low in patients with ON involvement, whereas VEP latencies were long. Visual reactivity was negatively correlated with VEP amplitude and RFNL measurements, and positively correlated with VEP latency. Conclusions The present study supports that cerebrovascular reactivity is preserved in patients with RRMS except for attacks, and neurovascular reactivity is increased in patients without ON involvement.

Patterned edge-illuminated display for clinical examination of visual evoked potentials using simultaneous magnetic resonance imaging

PurposeCommonly used technologies for visual pattern stimulation cannot operate in a magnetic resonance imaging room because they can interfere with the operation of the scanner and are vulnerable to its electromagnetic and magnetic fields. The aim of this single-center prospective observational study was to introduce a novel, structurally uncomplicated, easy-to-maintain, patterned edge-illuminated display (PEID) device for visual pattern-reversal stimulation, compare it with a commonly used cathode ray tube screen, and verify the equivalence of quantitative assays. Materials and methodsThe left and right eyes of 36 healthy participants with undilated pupils were examined on a commercial visual evoked potential (VEP) apparatus and on the PEID device, where pattern-reversal transient VEPs were elicited by checkerboard stimuli with large (0.89°; 0.86°–0.92°) and small (0.21°; 0.20°–0.23°) checks. ResultsThe PEID device demonstrated the required reliability and dynamic characteristics, as well as precise time-locking required for a VEP diagnosis. The results of Deming's correlation analysis showed that both the commercial cathode ray tube monitor and the PEID device produced identical VEP results within the context of experimental uncertainty. The standard deviation of Deming's regression may indicate the uncertainty of the VEPs measured in clinical practice. The Bland-Altman analysis of the mean showed no significant difference in the amplitude and peak time of VEPs measured on the PEID device compared to that of the commercial cathode ray tube monitor. ConclusionsThe presented PEID device meets all the required standards and can be easily installed in various types of commercial magnetic resonance imaging scanners.

The effect of different blood groups on visual evoked potentials

Introduction and aim. Purpose of the study is to determine whether it is required to use different standards when evaluating visual evoked potential (VEP) measurements of healthy individuals with different blood groups. Material and methods. The study consisted of healthy individuals with different blood groups who have applied to the ophthalmology and neurology outpatient clinic of Düzce University Medical Faculty from January to December 2022. The patients went through detailed ophthalmologic examination and VEP test and only the ones with normal results were included to the study. Results. The study consisted of 119 individuals, with a blood group distribution of 30 A, 29 B, 30 AB and 30 O. VEP latency and amplitude changes were compared and no significant difference was observed within 4 groups in terms of P100 and N70 latency and amplitudes. There was N70 latency prolongation in Rh- group and this difference was found to be statistically significant (p=0.009). Rh+ group was found to be high in terms of P100 amplitudes and this was considered statistically significant (both p=0.023). Conclusion. There was no statistically significant difference in the VEP parameters of the individuals with the ABO blood groups hence same VEP normal values can be used for ABO blood groups.

Pattern visual evoked potential and foveal sensitivity in amblyopia.

Amblyopic eyes show impaired visual functions such as poor visual acuity and reduced foveal sensitivity. The purpose of this study was to determine the association between foveal threshold and visual evoked potentials (VEP) in strabismic and anisometropic amblyopia. Forty-five subjects (age range: 7-28years, 43.3% female) including 15 strabismic and 15 anisometropic amblyopes, and 15 age-similar control subjectsparticipated in this study. Each subject had pattern visual evoked potentialsand foveal threshold recorded in each eye using RetiScan (Roland Consult, Germany) and Humphrey Visual Field Analyzer II (HFA II; Carl Zeiss Meditec Inc., Dublin, CA), respectively. These outcomes were comparedamong the amblyopic eyes, their fellow eyes, and the control eyes. Compared to the amblyopic eyes (Mean ± SD: 33.4 ± 3.48dB), the foveal threshold was higher in fellow eyes (37.0 ± 2.04dB, p = 0.0002) and incontrol eyes (38.7 ± 0.96dB, p < 0.0001). Strabismic amblyopes had a lower foveal threshold than anisometropic amblyopes (31.8 ± 3.86 vs. 35.0 ± 2.17dB, p = 0.005). Relative to the P100 peak time in fellow eyes (1°checks:116.1 ± 9.00ms; 0.25°checks:118.8 ± 5.67ms), amblyopic eyes had delayed P100 peak times for both 1° (122.7 ± 11.4ms, p < 0.0001) and 0.25° (130.4 ± 11.2ms, p < 0.0001) check sizes. There were also significant differences in P100 peak time between amblyopic and control eyes (1°:122.7 ± 11.4 vs.112.4 ± 5.01ms, p = 0.15; 0.25°:130.4 ± 11.2 vs.113.9 ± 5.71ms, p < 0.0001) and between fellow and control eyes (0.25°:118.8 ± 5.67 vs.113.9 ± 5.71ms, p = 0.009). Amblyopic eyes exhibited lower N75-P100 amplitudes than fellow eyes (1°:12.6 ± 7.96 vs.15.9 ± 8.82µV, p = 0.01; 0.25°:10.6 ± 6.11 vs. 15.8 ± 10.6µV, p = 0.001) and control eyes (0.25°: p = 0.0008). Foveal threshold correlated negatively with P100 peak time (1°: r = -0.45, p = 0.002 and 0.25°: r = -0.58, p < 0.0001) and positively with N75-P100 amplitude responses (1°: r = 0.42, p = 0.004 and 0.25°: r = 0.52, p = 0.002). Amblyopic eyes showed reduced pattern VEP amplitudes and delayed peak times with significant associations with the foveal sensitivity. However, the VEP measures overlapped extensively between amblyopic and control eyes with no apparent criterion value for optimal discrimination, suggesting that foveal sensitivity might be a better discriminator of amblyopia than pattern VEP.

Neurobehavioral measures of coincidence anticipation timing.

Coincidence anticipation (CA) refers to the ability to coordinate responses to the arrival of a moving object. This study investigates the neurobehavioral processes that underlie CA through the measurement of electroencephalography (EEG) recorded during a CA task on a 17-foot plastic rail with evenly spaced LED lights. Participants responded at the anticipated moment a sequence of successively lit LEDs coincided with a stationary target. Healthy young adult participants (Mage = 21) performed six blocks with movement at 20, 30, or 40 mph and the direction either inbound or outbound relative to the participant. Behavioral results demonstrated a main effect of speed and an interaction between speed and direction, with outbound motion producing early responses and inbound motion producing delayed responses that increased at greater speeds. EEG demonstrated characteristic P1, N2, and P3-like visual evoked potentials (VEPs). VEP amplitudes revealed a significant direction by channel interaction for the P1, indicative of more medial responses for inbound motion. Significant laterality differences were present in the N2, whereas the P3 component produced significant main effects and interactions of speed and direction. This novel combination of three-dimensional CA with EEG demonstrates systematic brain responses that are tuned for motion speed and sensitive to different egocentric motion patterns thereby shedding new light on the mechanism of human visual-motor control.