Visual Evoked Potential Responses Research Articles

Prolonged Visual Evoked Potential Latencies in Dogs Naturally Infected with Canine Distemper Virus

Canine distemper (CD) is a deadly, multi-system infection caused by a Morbillivirus. The canine distemper virus (CDV) frequently affects the nervous system with demyelinating leukoencephalitis, the most common neurological lesion. The disease has been linked to multiple sclerosis (MS) in humans due to similar clinical presentation and pathophysiological mechanisms. In MS, visual evoked potentials (VEPs) have been identified as a reliable marker for disease progression, enabling the early detection of clinically suspected lesions. The aim of this study was to determine if there are any abnormalities in VEP responses in dogs with neurological CD. Visual evoked potentials and electroretinogram (ERG) were recorded at both the cranial and spinal levels in dogs naturally infected with CDV and in healthy dogs. The results in the CDV-infected group revealed a bilateral increase in the latency of N1, P1, N2, P2, and N3 waves of the VEPs, without any alterations in their amplitudes. No significant differences were observed in the ERG between the groups. These results suggest that altered VEP responses could serve as an early diagnostic indicator of neurological damage caused by distemper. Therefore, conducting these studies could potentially aid in the detection of central nervous conduction disorders during the subclinical phases of the disease.

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.

Poster Session II: Attentional modulation of the achromatic and chromatic reversal VEP.

Previous literature has consistently revealed attentional modulation of the Visual Evoked Potential (VEP) response to achromatic pattern reversal stimuli but little to no attentional modulation of the VEP response to chromatic pattern onsets. Magnetic Resonance Imaging (MRI) research, however, has reported modulation of the responses to both achromatic and chromatic pattern reversal stimuli. Numerous methodological differences including mode of presentation, stimulus contrast, and attentional demand, make comparison of these results difficult. In this study, we report the results of experiments using comparable perceptual contrasts, pattern reversals, and a coextensive and highly-demanding, multiple object tracking (MOT) task. Our findings support prior VEP results indicating that although achromatic VEPs are modulated by attention, chromatic VEPs are more robust to attentional modulation, even for highly demanding distractor tasks. We also found that when compared to a non-attentional condition, the attenuation of the VEP when attending to the MOT task was greater in magnitude than the enhancement of the VEP when attending to the VEP stimulus. This supports prior conclusions, that while avoiding active distraction is likely important, insuring an "attentive state" is not always necessary when recording VEPs. Further experiments are underway to investigate why attentional modulation of chromatic signals in early visual cortex are observed in MRI but not VEP recordings.

Silicone oil insulation effects on flash electroretinogram and visual evoked potential in patients with retinal detachment

BackgroundSilicone oil is used as endotamponade following vitreoretinal surgery to maintain the retina reattached when indicated. This study investigates the hypothesis that silicone oil causes insulation effects on the retina by affecting its response to light. MethodsElectrophysiological responses to a flash stimulus were recorded using full-field electroretinography (ERG) and visual evoked potentials (VEP). Recordings were performed in 9 patients who underwent surgery for retinal detachment, before (1–2 days) and after (2–3 weeks) silicone oil removal (SOR) in both the study and the control eye. Flash ERG and VEP recordings were performed according to the ISCEV standard protocol. ResultsStatistically significant differences were found in the study eye in the amplitudes of the ERG responses and their corresponding ratios, i.e. the amplitude after SOR over the amplitude before SOR, in all conditions tested. No differences were observed in the control eye. The mean ratio of photopic ERG response was 3.4 ± 2.4 for the study and 1.0 ± 0.3 for the control eye (p<0.001). The mean ratio of ERG flicker response was 3.1 ± 2.4 and 1.0 ± 0.3, respectively (p = 0.003). Scotopic flash ERG ratio was 5.0 ± 4.4 for the study and 1.3 ± 0.6 for the control eye (p = 0.012). No differences were observed for the amplitude and latency of flash VEP response after SOR. ConclusionsSilicone oil causes a reduction in flash ERG responses; no effect was found on flash VEP responses. ERGs in eyes filled with silicone oil should not be considered representative of retinal functionality, in contrast to VEPs, which are not affected by silicone oil presence.

Effect of Changes in the Area Ratio of Red/Blue Green Eyeshadow on Cognitive Processing in the Brain

Purpose: To conduct electroencephalography (EEG) and visual evoked potentials (VEPs) measurements to establish quantitative data on brainwave responses to changes in eyeshadow color, specifically the area ratio of red (R) and blue green (BG) eyeshadows.Methods: A study was conducted on 60 males and females in their 20s using R, BG eyeshadow to determine brainwave responses via spontaneous EEG and VEPs while presenting stimuli with changes in area. The analysis focused on brainwave responses to changes in area.Results: The brainwave responses to color stimuli demonstrated the maximum activity in the occipital lobe. Specifically, the results of the EEG analysis indicated the highest level of psychological relaxation response at the golden ratio (1.61) of the eyeshadow area. Furthermore, when participants wore BG eyeshadow, their brainwave responses remained stable, with consistent alpha wave activation. The presentation of stimuli using only the R eyeshadow resulted in a significant increase in arousal and attention levels among the participants. Perceptual responses exhibited variations based on the ratio of the main color and point color in the color contrast, and rapid VEPs responses were observed specifically under high saturation conditions. Furthermore, the study revealed a high correlation between the brainwave response results and color images, indicating that an optimal ratio of color areas can maximize the impact of the color image.Conclusion: The results of this study suggest that by adjusting the area ratio of colors, it is possible to scientifically determine and achieve the desired color effects in color planning. The brain cognitive responses, resulting from variations in eyeshadow area, can serve as valuable quantitative data for image-making purposes, and can be applied to various fields in the beauty industry to expand their usability

Is the prolongation latency of visual evoked potentials a pathological sign in children with Down’s syndrome without ocular abnormalities? Case–control study of children with Down’s syndrome

ObjectiveTo evaluate retino-cortical function in children with Down’s syndrome (DS) and no evident ocular abnormalities beyond mild refractive error, by recording visual evoked potentials (VEP) in response to pattern-reversal stimuli...

Different visual evoked potentials in neuromyelitis optica spectrum disorder-related optic neuritis and idiopathic demyelinating optic neuritis: a prospective longitudinal analysis

BackgroundTo investigate different visual evoked potential (VEP) patterns in neuromyelitis optica spectrum disorder-related optic neuritis (NMOSD-ON) and idiopathic demyelinating optic neuritis (IDON).MethodsThis was a longitudinal, prospective, case-control study. Eighty-four Chinese patients with acute optic neuritis were enrolled, including 26 NMOSD-ON patients and 58 IDON patients. All the patients underwent best-corrected visual acuity (BCVA) and full-field pattern reversal VEP recordings at the onset, 1 month, 3 months, and 6 months.ResultsWithin 15′ checks, the NMOSD-ON patients had more severe VEP amplitude reduction at 6 months (2.39 ± 4.63 μV vs. 6.96 ± 8.88 μV, P = 0.034). However, the IDON patients showed more frequently normal VEP response at 3 months (24.0% vs. 4.5%, P = 0.017), and only prolonged P100 peak latency with normal amplitude (L) at 6 months (30.0% vs. 57.8%, P = 0.048). Within 60′ checks, no significant difference in VEP parameters between the two groups was found at each follow-up (P > 0.05). ConclusionsThe NMOSD-ON patients showed more severe axonal damage and worse axonal recovery than the IDON patients. VEP elicited by smaller check size was more sensitive to visual pathway abnormality in NMOSD-ON.

Mice with disrupted canonical phototransductive pathways retain robust VEP responses under light-adapted conditions

The Gnat1−/−, Gnat2−/−, Opn4−/− triple knockout (TKO) mouse line, lacking alpha transducins in rods and cones and melanopsin in ip-RGCs, is generally considered to be blind. Previous studies using electroretinograms have found that these animals retain residual light sensitivity only under dark-adapted conditions. Here, we show cortical responses to light (visual evoked potentials (VEPs)) recorded from TKO mice under light-adapted conditions. VEPs were recorded from C57BL/6J mice (n=6) and TKO mice (n=5) via 50ms flashes over 4 log units of intensity, with maximal illuminance of 44.3 mW/cm∧2 at the surface of the contralateral eye (λcenter = 530nm).

Contributed Session II: Attentional Modulation of Early Cortical Chromatic Responses

Prior research demonstrates that attention can modulate the amplitude of achromatic (black and white) pattern reversal stimuli. Similarly, MRI research has shown attentional modulation of BOLD responses to both chromatic and achromatic stimuli. However, prior research has also demonstrated that the chromatic onset visual evoked potential (VEP) is robust to attentional modulation (e.g., Highsmith & Crognale, 2010; Wang & Wade, 2011) with either spatially contiguous or spatially disparate manipulations. It is possible that more demanding attentional tasks than those that have been used previously, may reveal attentional modulation of the chromatic VEP. Here we report the results of experiments in which we recorded chromatic and achromatic VEPs while subjects performed multiple object tracking (MOT) tasks with several levels of difficulty. Steady-state onset responses were recorded at 3hz for stimuli modulated along the chromatic and achromatic axes. Our preliminary results suggest that the increased attentional demand provided by MOT can reveal a clear, but idiosyncratic modulation of chromatic VEP responses. The question remains whether or not chromatic and achromatic mechanisms share similar attentional gain processes as reflected in the VEP. We are currently characterizing the nature of these attentional gain mechanisms.

Macular Morpho-Functional and Visual Pathways Functional Assessment in Patients with Spinocerebellar Type 1 Ataxia with or without Neurological Signs.

Spinocerebellar ataxia type 1 (SCA-ATXN1) is an autosomal dominant, neurodegenerative disease, caused by CAG repeat expansion in the ataxin-1 gene (ATXN1). In isolated reports of patients with neurological signs [symptomatic patients (SP)], macular abnormalities have been described. However, no reports exist about macular anomalies in SCA1 subjects carrying the ATXN1 mutation without neurological signs [not symptomatic carriers (NSC)]. Therefore, the main aim of our work was to evaluate whether the macular functional and morphological abnormalities could be detectable in SP, genetically confirmed and with neurological signs, as well as in SCA-ATXN1-NSC, harboring pathogenic CAG expansion in ATXN1. In addition, we investigated whether the macular involvement could be associated or not to an impairment of RGCs and of their fibers and of the neural conduction along the visual pathways. Herein, nine SCA-ATXN1 subjects (6 SP and 3 NSC) underwent the following examinations: visual acuity and chromatic test assessments, fundus oculi (FO) examination, macular and peripapillary retinal nerve fiber layer thickness (RNFL-T) analysis by Spectral domain-Optical Coherence Tomography (Sd-OCT) acquisition, multifocal electroretinogram (mfERG), pattern reversal electroretinogram (PERG) and visual evoked potentials (VEP) recordings. In four eyes of two SP, visual acuity reduction and chromatic abnormalities were observed; in three of them FO changes associated with macular thinning and outer retinal defects were also detected. In three NSC eyes, slight FO abnormalities were associated with qualitative macular morphological changes. By contrast, abnormal mfERG responses (exclusively from foveal and parafoveal areas) were detected in all SP and NSC (18 eyes). No abnormalities of PERG values, RNFL-T, and VEP responses were found, but in one SP, presenting abnormal papillo-macular bundle neural conduction. Results from our SCA-ATXN1 cohort suggest that a macular dysfunction, detectable by mfERG recordings, may occur in the overt disorder, and unexpectedly in the stage of the disease in which there is still an absence of neurological signs. In NSC, an exclusive dysfunction of preganglionic macular elements can be observed, and this is associated with both normal RGCs function and neural conduction along the visual pathways.

C57BL/6J and DBA/2J strains present opposite sex differences in flash visual evoked potential latency: A possible confusing factor in gender studies on neurological diseases’ transgenic models

The cholinergic neurotransmitter system in the brain is crucial in processing information related to cognitive, behavioral, and motor functions. A cholinergic dysfunction has been correctly described as one of the primary causes of neurodegenerative diseases. Differences in levels of acetylcholine or expression and function of receptors in selected brain areas have been indicated as one of the causes of sexual dimorphism in neurotransmission. However, variability in results among studies based on different mice strains could affect conclusions on this topic. Visual evoked potentials (VEPs) of male and female DBA/2J and C57BL/6J mice, which are two of the most common strains backgrounds in use for developing transgenic mice models of neurological diseases, have been studied. Effects induced by a single low dose of physostigmine have also been performed to evaluate the cholinergic system involvement. VEPs responses to luminous stimuli in C57BL/6J mice have shown a consistently lower latency than in DBA/2J, confirming the previous observation of strain differences in cholinergic function. Interestingly, strains present an opposite-sex difference in VEP latency not apparently related to sensitivity to physostigmine. These findings point at paying extreme attention to the choice of the genetic background of the animal model, especially in those basic and pre-clinical experiments that involve visual functioning.

A reduced visual pathway response in infantile nystagmus syndrome

To investigate visual cortical responses in children with infantile nystagmus syndrome (INS) and the potential contribution of foveation periods. The medical records of children with INS who had visual evoked potential (VEP) recordings to reversing checkerboards and onset of horizontal gratings were reviewed retrospectively. VEP recordings underwent objective selective averaging for extraction of brief periods having consistent amplitude and timing with the stimulus presentation. VEP amplitude, latency, and signal-to-noise ratios (SNR) were compared to results from published age-matched controls under the same conditions. Relative foveation in INS subjects was determined from the proportion of time a video-oculography recording met eye position and velocity criteria. A total of 26 children met inclusion criteria. Selective averaging increased VEP amplitude and SNR in INS by 270%-420% compared to standard averaging (P<0.0001). The INS change in VEP response was greater for reversing checkerboard stimulation than horizontal-grating onset and was significantly greater than that in controls (P<0.001). Latency was not changed by selective averaging. Relative foveation was correlated with increasing VEP amplitude (P=0.02) and number of trials chosen for selective averaging (P<0.01). After selective averaging, relative foveation correlated with VEP amplitude to reversing checkerboards only (P=0.007). Nystagmus likely causes a reduced visual cortical response in children with INS. A significantly larger response can be extracted from brief periods during nystagmus eye movements, supporting the hypothesis that the INS visual system generates a larger cortical signal during brief foveation periods.

Normative values of visual evoked potential in adults.

Purpose:Visual evoked potentials (VEP) are used to determine the function of visual pathway from the optic nerve to visual cortex. Various factors may affect VEP response, viz., technical and environmental. The aim of this study is to obtain the normative value of VEP latency and amplitude parameters in adulthood in Indonesia, as well as the relationship of height, weight, body mass index (BMI), head circumference, and visual acuity with the variety of latency and amplitude values of VEP parameters.Methods:It is a cross-sectional study on 120 healthy subjects consisting of 60 males and 60 females between 18 and 65 years old. Height, weight, BMI, head circumference, and visual acuity were measured and continued with VEP examination using a 26′ checkerboard pattern on the left and right eyes alternately. All data were collected and analyzed with the Shapiro–Wilk test using statistical software R version 3.5.2.Results:Mean value of P100 latency (interocular latency) of left and right eye were 104.6 ± 3.4 ms and 104.1 ± 3.4 ms, respectively, as well as 9.8 ± 4.7 μV and 10.3 ± 5.4 μV for the amplitude. There was no significant difference between the male and female group, as well as on the age group. Female significantly exhibited a higher P100 amplitude than male. The greater the age, the lower amplitude of P100 significantly.Conclusion:Gender and age do not affect the P100 latency value but only affect P100 amplitude. Height, weight, BMI, head circumference, and visual acuity also do not affect the P100 latency and amplitude.

The relationship between aquaporin-4 antibody status and visual tract integrity in neuromyelitis optica spectrum disorders: A visual evoked potential study

BackgroundOptic neuritis (ON) is one of the hallmark symptomatic features of neuromyelitis optica spectrum disorders (NMOSD). The majority of patients with NMOSD present highly specific autoantibodies against aquaporin-4 (AQP4). A number of studies have reported poor visual acuity outcomes in individuals with AQP4 seropositive NMOSD, but no such relationship has been found with regard to visual evoked potentials (VEP) parameters such as the amplitude and latency of the P100 component. In this paper, we aimed (i) to describe VEP responses in patients with NMOSD; (ii) to analyze those results based on a scoring system; and (iii) to investigate the association between the VEPs and AQP4 antibody status. MethodsWe retrospectively analysed the VEP responses of 40 patients with a diagnosis of NMOSD (according to the 2015 IPND criteria), including 16 with AQP4-postive status (AQP4[+]) and 24 with AQP4-negative status (AQP4[-]). In the first step, we measured the P100 peak latency and P100-N2 peak-to-peak amplitude in each patient. In the second, we converted these measures to the VEP score (0–10) using the scoring proposed by Jung et al. (2008). All recordings were performed using the same VEP device and testing protocol. ResultsAbnormal VEPs were recorded in 25 of 40 patients (62.6%). Of these, 17 (42.5%) had prolonged P100 latency, and 8 (20%) had no response detected in at least one eye. The patients with ON as the initial relapse symptom had significantly higher median VEP scores than those who experienced the longitudinally extensive transverse myelitis (LETM) at the disease onset (7.0 [in­terquar­tile range (IQR), 2.0–8.0] vs. 0.0 [IQR, 0.0–4.0], p<0.001). A lack of VEP response in at least one eye was detected more frequently in the AQP4[+] group than the AQP4[-] group (7/16 vs. 1/24, p<0.005). Logistic regression model controlling for age, gender, disease duration, and the type of relapse at onset showed an independent impact of AQP4[+] status (OR=35.45, p = 0.018) on the higher rate of absent VEP responses. In the entire group of patients (n = 40), those with AQP4[+] showed a small tendency towards a higher median VEP score (4.0 [IQR, 0.0–7.8] vs. 1.0 [IQR, 0.0–4.0], p = 0.304). Among individuals with abnormal responses (n = 25), the patients with AQP4[+] had significantly higher median VEP scores (7.0 [IQR, 4.0–8.5] vs. 3.0 [IQR, 1.0–7.0], p = 0.034) and more common bilateral involvement of the optic tracts (80% vs. 40%, p = 0.048) than those who were seronegative for anti-AQP4 antibody. A median regression analysis model controlling for age, gender, disease duration, type of onset, and number of relapses in last 12 months showed an independent association between the AQP4-positive status and a higher VEP score in patients with NMOSD (t = 2.882, df=2, p = 0.007). ConclusionVEP study remains a useful tool in the assessment of NMOSD patients. Due to the high prevalence of absent VEPs in NMOSD patients, the scoring system appears to be more applicable for the precise analysis of VEP recordings. There is a positive association between the AQP-positive serostatus and the poorer outcome in VEP responses, especially in patients with severe impairment of the optic nerve(s).

The electrophysiological response to polarization-modulated patterned visual stimuli

Recent reports indicate that the subjective ability of humans to discriminate between polarization E-vector orientations approaches that of many invertebrates. Here, we show that polarization-modulated patterned stimuli generate an objectively recordable electrophysiological response in humans with normal vision. We investigated visual evoked potential (VEP) and electroretinographic (ERG) responses to checkerboard patterns defined solely by their polarization E-vector orientation alternating between ± 45°. Correcting for multiple comparisons, paired-samples t-tests were conducted to assess the significance of post-stimulus deflections from baseline measures of noise. Using standard check pattern sizes for clinical electrophysiology, and a pattern-reversal protocol, participants showed a VEP response to polarization-modulated patterns (PolVEP) with a prominent and consistent positive component near 150 ms (p < 0.01), followed by more variable negative components near 200 ms and 300 ms. The effect was unrecordable with visible wavelengths >550 nm. Further, pseudo-depolarization negated the responses, while control studies provided confirmatory evidence that the PolVEP response was not the product of luminance artefacts. Polarization-modulated patterns did not elicit a recordable ERG response. The possible origins of the PolVEP signals, and the absence of recordable ERG signals, are discussed. We conclude that evoked cortical responses to polarization-modulated patterns provide an objective measure of foveal function, suitable for both humans and non-human primates with equivalent macular anatomy.

Impact of Intermittent Hypoxia on Peripheral Nervous Systems in Obstructive Sleep Apnea Syndrome

Objectives: Intermittent hypoxia resulting in endothelial dysfunction in microvascular circulation constitutes one of the mechanisms underlying complications of obstructive sleep apnea syndrome (OSAS), such as hypertension and atherosclerosis. The role of intermittent hypoxia on peripheral nerves, however, is still debated. Here, we designed a study in patients with OSAS to investigate different levels of the central and peripheral nervous systems, in order to delineate what kind of pathologic substrate was present, if any, and at which level of the neuromuscular pathway. Methods: A total of 20 patients with OSAS and 18 sex- and age-matched healthy controls were enrolled in our study. All participants underwent nerve conduction studies (NCSs) to analyze peripheral nerves, evoked potentials for somatosensory, visual evoked potential (VEP) and brainstem auditory pathways, blink reflex studies to analyze brainstem and subcortical structures, and transcranial magnetic stimulation to analyze the motor cortex and corticospinal pathway. Results: A comparison of NCSs between the two groups showed that the motor amplitudes of the ulnar nerve (P = 0.015) and sensory amplitudes of the sural nerve (P = 0.026) were significantly smaller in the OSAS group than those in the control group. The mean P100 amplitudes of VEP responses were 7.11 ± 2.73 μV in the OSAS group and 9.75 ± 3.52 μV in the control group (P = 0.022). In correlation analysis, the amplitude of P100 responses was positively correlated with the lowest oxygen saturation (P = 0.026). Conclusion: Our results confirmed the presence of generalized axonal involvement in the peripheral nervous system in OSAS, probably secondary to chronic intermittent hypoxemia.

Deep Learning for Automatically Visual Evoked Potential Classification During Surgical Decompression of Sellar Region Tumors.

PurposeDetection of the huge amount of data generated in real-time visual evoked potential (VEP) requires labor-intensive work and experienced electrophysiologists. This study aims to build an automatic VEP classification system by using a deep learning algorithm.MethodsPatients with sellar region tumor and optic chiasm compression were enrolled. Flash VEP monitoring was applied during surgical decompression. Sequential VEP images were fed into three neural network algorithms to train VEP classification models.ResultsWe included 76 patients. During surgical decompression, we observed 68 eyes with increased VEP amplitude, 47 eyes with a transient decrease, and 37 eyes without change. We generated 2,843 sequences (39,802 images) in total (887 sequences with increasing VEP, 276 sequences with decreasing VEP, and 1680 sequences without change). The model combining convolutional and recurrent neural network had the highest accuracy (87.4%; 95% confidence interval, 84.2%–90.1%). The sensitivity of predicting no change VEP, increasing VEP, and decreasing VEP was 92.6%, 78.9%, and 83.7%, respectively. The specificity of predicting no change VEP, increasing VEP, and decreasing VEP was 80.5%, 93.3%, and 100.0%, respectively. The class activation map visualization technique showed that the P2-N3-P3 complex was important in determining the output.ConclusionsWe identified three VEP responses (no change, increase, and decrease) during transsphenoidal surgical decompression of sellar region tumors. We developed a deep learning model to classify the sequential changes of intraoperative VEP.Translational RelevanceOur model may have the potential to be applied in real-time monitoring during surgical resection of sellar region tumors.

A BCI Gaze Sensing Method Using Low Jitter Code Modulated VEP.

Visual evoked potentials (VEPs) are used in clinical applications in ophthalmology, neurology, and extensively in brain–computer interface (BCI) research. Many BCI implementations utilize steady-state VEP (SSVEP) and/or code modulated VEP (c-VEP) as inputs, in tandem with sophisticated methods to improve information transfer rates (ITR). There is a gap in knowledge regarding the adaptation dynamics and physiological generation mechanisms of the VEP response, and the relation of these factors with BCI performance. A simple, dual pattern display setup was used to evoke VEPs and to test signatures elicited by non-isochronic, non-singular, low jitter stimuli at the rates of 10, 32, 50, and 70 reversals per second (rps). Non-isochronic, low-jitter stimulation elicits quasi-steady-state VEPs (QSS-VEPs) that are utilized for the simultaneous generation of transient VEP and QSS-VEP. QSS-VEP is a special case of c-VEPs, and it is assumed that it shares similar generators of the SSVEPs. Eight subjects were recorded, and the performance of the overall system was analyzed using receiver operating characteristic (ROC) curves, accuracy plots, and ITRs. In summary, QSS-VEPs performed better than transient VEPs (TR-VEP). It was found that in general, 32 rps stimulation had the highest ROC area, accuracy, and ITRs. Moreover, QSS-VEPs were found to lead to higher accuracy by template matching compared to SSVEPs at 32 rps. To investigate the reasons behind this, adaptation dynamics of transient VEPs and QSS-VEPs at all four rates were analyzed and speculated.

Neuroenhancement and neuroprotection by oral solution citicoline in non-arteritic ischemic optic neuropathy as a model of neurodegeneration: A randomized pilot study.

PurposeTo evaluate whether treatment with Citicoline in oral solution (OS-Citicoline) would increase visual function, retinal ganglion cells (RGCs) function, and neural conduction along visual pathways (neuroenhancement), and/or induce preservation of RGCs fibers’ loss (neuroprotection) in non-arteritic ischemic optic neuropathy (NAION), a human model of neurodegeneration.MethodsThirty-six patients with NAION and 20 age-matched controls were enrolled. Nineteen NAION patients received 500 mg/day of OS-Citicoline for a 6-month period followed by 3-month of wash-out (NC Group); 17 NAION patients were not treated (NN Group) from baseline to 9 months. In all subjects at baseline, and in NC and NN eyes at 6 and 9 months of follow-up, we assessed Visual Acuity (VA), Pattern Electroretinogram (PERG), Visual Evoked Potentials (VEP), retinal nerve fiber layer thickness (RNFL-T), and Humphrey 24–2 visual field mean deviation (HFA MD). Mean differences were statistically evaluated with ANOVA between Groups, and linear correlations were analysed with Pearson’s test.ResultsAt 6 months, significant differences between groups for all parameters were observed (ANOVA, p<0.01). In NC eyes, VA increased, PERG responses increased, VEP recordings improved and were significantly correlated with increases in HFA MD (p<0.01), and RNFL-T was unmodified or improved. In contrast, in NN eyes, VA, PERG, VEP responses, RNFL-T, and HFA MD were further worsened. Significant differences were still present at 9-month follow-up in the NN Group and after 3 months of OS-Citicoline wash-out in NC eyes.ConclusionsOS-Citicoline treatment induced neuroenhancement (improvement in RGCs function and neural conduction along visual pathways related to improvement of visual field defects) and neuroprotection (unmodified or improved RNFL morphological condition) in a human model of NAION involving fast RGCs degeneration.Trial registrationClinicalTrials.gov NCT03758118.

Correlation of Visual Evoked Potentials with Duration of Diabetes in Type 2 Diabetes Mellitus Patients

&#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; Introduction&#x0D; Chronic hyperglycemia of diabetes is associated with dysfunction and failure of various organs, especially the eyes, kidneys, neves, heart and blood vessels. Visual evoked potential (VEP) test evaluates how the visual system responds to light. As it tests the function of the visual pathway from the retina to the occipital cortex, VEP is a useful clinical tool in the diagnosis and documentation of visual impairment in many ophthalmological disorders.&#x0D; Analysis of pattern reversal VEPs may provide early diagnosis of diabetic changes and determine prognosis during treatment. The visual evoked potential is suggested to be a sensitive indicator of functional changes in the visual processing pathway.&#x0D; Aims and Objectives&#x0D; The objective of this study was to establish whether duration of DM has an effect on the VEP measurements, P100 wave latency.&#x0D; Material and methods&#x0D; VEP was recorded in 60 type 2 diabetic patients and compared to 60 age and sex matched normal healthy non-diabetic controls. The patients were divided into three groups based on the duration of diabetes. VEP was recorded with a pc based, two channel, RMS EMG EP MK II machine. Comparison between two groups were done using independent Students’ ‘t’ test.. One way ANOVA (Analysis of Variance) and multiple comparisons were done using post hoc Tukey Multiple Comparison Test to compare the variables between the three study groups. To determine correlation between variables, Pearson's correlation coefficient was used. The mean difference was statistically significant at p&lt;0.05&#x0D; Result&#x0D; P100 wave latency was significantly longer in diabetic patients as compared to normal controls (P&lt;0.001); There was significant reduction in N75-P100 amplitudes in diabetic subjects(p&lt;0.01). Duration of diabetes was found to influence the VEP parameters as statistically significant increase in the mean P100 latency with the duration of the disease.(110.2+6.51 ms in group &lt;3 yrs duration of DM, 113.4 +5.00 ms in 4–6 yrs duration group, 118.2+4.23 ms in 7–10 years duration group) (p&lt; 0.01). On applying, Pearson's correlation coefficient test, significant positive correlation was observed between P100 latency and duration of diabetes. (r = 0.5803; p &lt;0.001).&#x0D; Conclusion&#x0D; It is concluded that diabetes has effect on the visual pathway and changes in VEP response in diabetic patients are correlated with duration of disease. So, VEP can be used for early diagnosis of diabetic changes of the visual pathway.&#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D;