Study Of Visual Evoked Potentials Research Articles

Cortical excitability in patients with migraine with aura and depressive symptoms: a visual evoked potentials study

Background: Migraine is a brain disorder characterized by recurring headache attacks, and emotional comorbidities, such as anxiety and depression, may influence the repetition of these attacks. The lack of sensory habituation is a common neurophysiological abnormality in migraine, and research suggests that it is under the influence of serotonin and other monoamines that are also involved in mood disorders. This study aimed to investigate the influence of emotional symptoms on cortical information processing in patients with migraine with aura by correlating cortical activity with self-perceived emotional distress. Methods: Visual evoked potentials from monocular stimulation were recorded in 16 patients with migraine with aura (MA) and 22 healthy volunteers (HV). The visual stimulus consisted of a full-screen black-and-white checkerboard pattern with a reversal rate of 1.55 Hz. 600 consecutive traces were collected and divided into six sequential blocks of 100 sweeps. Before the recording session, both MA patients and HV completed the Beck Depression Inventory (BDI) and State-Trait Anxiety Inventory (STAI). Pearson's correlation test was used to find correlations between electrophysiological and psychometric variables in HV and MA patients. Results: Compared to HV, MA patients showed a significant difference in the degree of habituation to repeated visual stimulation between the two groups, resulting in a habitation deficit. Psychometric test results showed that trait STAI and BDI values were significantly higher in MA patients. In the MA group, BDI correlated negatively with the amplitude of the first block and positively with the degree of habituation. Conclusions: These results highlight a link between the level of brain responsiveness and depressive symptoms in patients with MA. Further research is required to confirm whether the same correlations exist in patients with other headache disorders.

Visual evoked potential in generalized joint hypermobility: A case-control study.

Generalized joint hypermobility (GJH) can be the result of several hereditary connective tissue disorders, especially Ehlers-Danlos syndrome. Cerebrovascular manifestations are among the most common complications in this disorder, and understanding their extent can help better diagnosis and prevention of hazardous events. We investigated visual evoked potential (VEP) changes in patients with GJH and compared them with healthy individuals. Our case-control study included 90 patients who fulfilled the Beighton score (B score) for joint hypermobility and other 90 healthy participants. All of them went under VEP study, and the amplitude and latency of the evoked potential (P100) were compared to each other. The Case group had significantly higher B score (7.18±0.967 vs. 1.18±0.712), P100 latency (110.23±6.64ms vs. 100.18±4.273ms), and amplitude (6.54±1.26mv vs. 6.50±1.29mv) compared with the Control group, but the difference was only significant regarding B score, and P100 latency (p-value <.0001). Moreover, both latency and amplitude of P100 had significantly positive correlations with the B score in the Case group (p-value <.0001), but such correlations were not found in the Control group (p-value=.059). Our study could reveal VEP changes, especially significant P100 latency in GJH patients without previous neurologic or musculoskeletal disorders. Whether these changes are due to GJH itself or are predictive of inevitable neurologic disease or visual pathway involvement, particularly Multiple Sclerosis needs further investigation with longer follow-up periods.

Chronic Inflammatory Demyelinating Polyneuropathy and Evaluation of the Visual Evoked Potentials: A Review of the Literature.

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare autoimmune disorder characterised by the progressive demyelination of peripheral nerves, resulting in motor and sensory deficits. While much research has focused on clinical and electrophysiological aspects of CIDP, there is an emerging interest in exploring its impact on the visual system through visual evoked potentials (VEPs). This comprehensive review synthesises existing literature on VEP findings in CIDP patients, shedding light on their potential diagnostic and prognostic value. The review thoroughly examines studies spanning the last two decades, exploring VEP abnormalities in CIDP patients. Notably, VEP studies have consistently revealed prolonged latencies and reduced amplitudes in CIDP patients compared to healthy controls. These alterations in VEP parameters suggest that the demyelinating process extends beyond the peripheral nervous system to affect the central nervous system, particularly the optic nerve and its connections. The correlation between VEP abnormalities and clinical manifestations of CIDP, such as visual impairment and sensory deficits, underscores the clinical relevance of VEP assessment in CIDP management. Furthermore, this review addresses the potential utility of VEPs in aiding CIDP diagnosis and monitoring disease progression. VEP abnormalities may serve as valuable biomarkers for disease activity, helping clinicians make timely therapeutic decisions. Moreover, this review discusses the limitations and challenges associated with VEP assessment in CIDP, including variability in recording techniques and the need for standardised protocols. In conclusion, this review highlights the evolving role of VEPs as a non-invasive tool in CIDP evaluation. The consistent VEP abnormalities observed in CIDP patients suggest the involvement of the central nervous system in this demyelinating disorder. As our understanding of CIDP and its pathophysiology continues to evolve, further research in this area may lead to improved diagnostic accuracy and monitoring strategies, ultimately enhancing the clinical management of CIDP patients.

Characteristics and dynamics of pathological changes in visual evoked potentials in multiple sclerosis

Clarification of the characteristics and dynamics of changes in the main indicators of visual evoked potentials (VEP) for a reverse chess pattern in patients with multiple sclerosis (MS) at various stages of the disease and severity of disability. The study of VEP was carried out on 477 subjects, 120 of which were healthy volunteers and 357 patients with MS, including those with clinically isolated syndrome (CIS; 22.7%), remitting course (RT; 55.7%), primary progressive course (PPT; 8.4%), secondary progressive course (VPT; 13.2%). Disability was assessed using the Expanded Disability Status Scale (EDSS). A high sensitivity of VEP in the detection of demyelinating damage to the visual pathways, including subclinical, was noted already at the initial stages of MS, which increases with the progression of the disease from 77.8 to 97.8%. There was a significant increase in latency (r=0.42, p<0.05) and a decrease in amplitude (r= -0.26, p<0.05) of the P100 peak as the EDSS score increased. In patients with MS, 5 patterns of VEP were identified depending on the level and severity of damage to the visual pathways, where pattern 1 is normative VEP, pattern 5 is the absence of VEP recording in case of a pronounced axonal-demyelinating lesion of the visual pathways (prechiasmal/postchiasmal levels). Patterns 1 and 2 are most typical for CIS (22.2 and 53.1%) or RT (20.1 and 26.6%). Patterns 3 and 4 are typical for APT (70 and 20%) and VPT (48.9 and 21.3%), pattern 5 - for VPT (19.1%). Patterns 3-5 predominated in patients with higher EDSS (r=0.54, p<0.05). The classification of VEP changes into patterns makes it possible to identify the dissemination of a focal lesion in the projections of the visual pathways, which increases the diagnostic efficiency of the study and makes it possible to assess the severity of MS.

Different check sizes pattern-reversal visual evoked potentials study in patients with compensated hepatic cirrhosis

Background: Cirrhosis is a dynamic process starts after sustained inflammation, followed by necrosis of liver cells and fibrosis that occur as a normal wound healing response then nodular formation that eventually lead to hepatic dysfunction. Aim and objectives: Study the effect of hepatic cirrhosis on cerebral cortex and subcortical pathways using VEP, and Comparison between different VEP check sizes in detection of early encephalopathy among cirrhotics. Subjects and methods: This was a case/control study carried out on 45 cirrhotic patients, and 45 matched normal controls. All subjects underwent full opthalmological assesment prio to the conduction of the PVEP, after the approval of the ethical committee. Results: the studied cases had significantly more delayed latency and lower amplitude than the studied controls on both sides at both 1 degree and 15 minutes check sizes (P-value&lt;0.05), however 13 patiebts were detected by the 15 min check size to be abnormal on he contrary of the 1 degree chech size that detected changes only in 6 patients. Conclusion: Vep 15 min is more sensitive in detecting early changes in cirrhotic patients. denoting that most of the hepatic encephalopathy changes are affecting the central visual field.

Altered Processing of Visual Stimuli in Vestibular Migraine Patients Between Attacks: A Combined VEP and sLORETA Study.

Objective: Vestibular migraine (VM) is one of the most common causes of recurrent vertigo, but the neural mechanisms that mediate such symptoms remain unknown. Since visual symptoms and photophobia are common clinical features of VM patients, we hypothesized that VM patients have abnormally sensitive low-level visual processing capabilities. This study aimed to investigate cortex abnormalities in VM patients using visual evoked potential (VEP) and standardized low-resolution brain electromagnetic tomography (sLORETA) analysis.Methods: We employed visual stimuli consisting of reversing displays of circular checkerboard patterns to examine “low-level” visual processes. Thirty-three females with VM and 20 healthy control (HC) females underwent VEP testing. VEP components and sLORETA were analyzed.Results: Patients with VM showed significantly lower amplitude and decreased latency of P1 activation compared with HC subjects. Further topographic mapping analysis revealed a group difference in the occipital area around P1 latency. sLORETA analysis was performed in the time frame of the P1 component and showed significantly less activity (deactivation) in VM patients in the frontal, parietal, temporal, limbic, and occipital lobes, as well as sub-lobar regions. The maximum current density difference was in the postcentral gyrus of the parietal lobe. P1 source density differences between HC subjects and VM patients overlapped with the vestibular cortical fields.Conclusion: The significantly abnormal response to visual stimuli indicates altered processing in VM patients. These findings suggest that abnormalities in vestibular cortical fields might be a pathophysiological mechanism of VM.

Editors' note: Longitudinal optic neuritis-unrelated visual evoked potential changes in NMO spectrum disorders

In the article “Longitudinal optic neuritis-unrelated visual evoked potential changes in NMO spectrum disorders,” Drs. Ringelstein et al. observed progressive delays in visual evoked potential (VEP) latency, occurring independently of acute optic neuritis, in 167 patients with neuromyelitis optica spectrum disorders (NMOSD) using 548 longitudinally assessed full-field VEP studies over the course of ≥3 months. In response, Dr. Chen seeks clarification about the authors' finding of a reduction in VEP amplitude with ≥3 months of follow-up but not among those with ≥12 months of follow-up. Dr. Chen wonders whether there may be similar correlations between VEP amplitude and disease activity as seen with optical coherence tomography (OCT) measurements of the peripapillary retinal nerve fiber layer thickness—which seem to decrease in NMOSD patients with non-ocular relapses vs those with stable disease—and calls for prospective longitudinal studies with VEP, OCT, and MRI to further explore this topic. Responding to these comments, the authors note that whereas their more restricted analysis of patients with ≥12 months of follow-up was intended to address the potential amplification of measurement variability that may have occurred with their interpolation of shorter-interval data—i.e., for patients with <12 months follow-up—their sample size may have been insufficient to achieve significance for analyses of amplitude changes. Nonetheless, they note that latency findings showed consistent and reliable increases in both the main and sub-analyses. This exchange highlights the ongoing evolution of our understanding about progressive tissue damage in NMOSD, previously thought to occur only in the context of relapses. We agree with Dr. Chen that longitudinal correlation of visual tests of structure, physiology, and function will be necessary to understand how frequently subclinical progressive disease might occur in NMOSD. In the article “Longitudinal optic neuritis-unrelated visual evoked potential changes in NMO spectrum disorders,” Drs. Ringelstein et al. observed progressive delays in visual evoked potential (VEP) latency, occurring independently of acute optic neuritis, in 167 patients with neuromyelitis optica spectrum disorders (NMOSD) using 548 longitudinally assessed full-field VEP studies over the course of ≥3 months. In response, Dr. Chen seeks clarification about the authors' finding of a reduction in VEP amplitude with ≥3 months of follow-up but not among those with ≥12 months of follow-up. Dr. Chen wonders whether there may be similar correlations between VEP amplitude and disease activity as seen with optical coherence tomography (OCT) measurements of the peripapillary retinal nerve fiber layer thickness—which seem to decrease in NMOSD patients with non-ocular relapses vs those with stable disease—and calls for prospective longitudinal studies with VEP, OCT, and MRI to further explore this topic. Responding to these comments, the authors note that whereas their more restricted analysis of patients with ≥12 months of follow-up was intended to address the potential amplification of measurement variability that may have occurred with their interpolation of shorter-interval data—i.e., for patients with <12 months follow-up—their sample size may have been insufficient to achieve significance for analyses of amplitude changes. Nonetheless, they note that latency findings showed consistent and reliable increases in both the main and sub-analyses. This exchange highlights the ongoing evolution of our understanding about progressive tissue damage in NMOSD, previously thought to occur only in the context of relapses. We agree with Dr. Chen that longitudinal correlation of visual tests of structure, physiology, and function will be necessary to understand how frequently subclinical progressive disease might occur in NMOSD.

Use of VEPs as electrodiagnostic biomarkers of mild cognitive impairment

AbstractAlzheimer's disease (AD) and its precursor, mild cognitive impairment (MCI), are characterized by early onset of visuospatial impairment along with memory impairment and disorientation. Based on these clinical features, I hypothesized that visual impairment might be a candidate biomarker for early electrodiagnosis of MCI. Therefore, I have been focusing on the application of visual evoked potentials (VEPs) as a non‐invasive, simple, and objective method for evaluating visual impairment in MCI patients. In this review, I first outline the concept of the human visual system. Second, I briefly mention the basic technology of VEPs. Then, I describe the previous VEP studies on AD and MCI. These VEP studies have reported that the lower‐level visual pathways are less likely to be involved in AD and MCI, whereas the higher‐level visual streams frequently show VEP abnormalities. Finally, I introduce my new VEP techniques for examining visual impairment in MCI. VEPs with multimodal visual stimuli (especially, optic flow motion) are useful for distinguishing MCI patients from non‐impaired individuals. It may also be feasible to discriminate the type of dementia responsible for MCI. From this review, I stress that VEPs are plausible biomarkers for the early electrodiagnosis of MCI.

Evaluation of visual pathways using visual evoked potential in patients with diabetic retinopathy

Visual evoked potential (VEP) is an electrophysiological exploration to detect the response to light stimulus and reveal visual pathways. Aim: VEP study in patients with diabetes mellitus (DM), assessment of cortical and retinal activity, and identifying the role of this investigation in the diagnosis of diabetic retinopathy. Methods: A case-control study conducted to investigate two groups: the first group (G1) included 78 patients (156 eyes) with different stages of diabetic retinopathy, and the second group (G0) included 78 healthy subjects (156 eyes). All subjects have been ophthalmologically and neurologically tested, also using visual evoked potentials. The patients have been exposed to mono-ocular, non-patterned stimuli, using LED-goggles glasses. Results: A serious increase in P100 and N75 wavelength latency in diabetic patients has been observed when compared to healthy subjects (p<0.05), and a N135 value increase in patients with diabetes mellitus (p=0.06). In addition, the amplitude of the P100 wave has changed in diabetic patients in comparison to healthy subjects. Conclusions: Changes in latency of waves registered on the VEP pathway and the amplitude of the P100 wave have been observed in patients with diabetic retinopathy (89.7%), which proved the importance of this study in the diagnosis of diabetic retinopathy and the possibility to examine the prognosis of this disabling disease.

Longitudinal optic neuritis-unrelated visual evoked potential changes in NMO spectrum disorders.

To investigate if patients with neuromyelitis optica spectrum disorder (NMOSD) develop subclinical visual pathway impairment independent of acute attacks. A total of 548 longitudinally assessed full-field visual evoked potentials (VEP) of 167 patients with NMOSD from 16 centers were retrospectively evaluated for changes of P100 latencies and P100-N140 amplitudes. Rates of change in latencies (RCL) and amplitudes (RCA) over time were analyzed for each individual eye using linear regression and compared using generalized estimating equation models. The rates of change in the absence of optic neuritis (ON) for minimal VEP intervals of ≥3 months between baseline and last follow-up were +1.951 ms/y (n = 101 eyes; SD = 6.274; p = 0.012) for the P100 latencies and -2.149 µV/y (n = 64 eyes; SD = 5.013; p = 0.005) for the P100-N140 amplitudes. For minimal VEP intervals of ≥12 months, the RCL was +1.768 ms/y (n = 59 eyes; SD = 4.558; p = 0.024) and the RCA was -0.527 µV/y (n = 44 eyes; SD = 2.123; p = 0.111). The history of a previous ON >6 months before baseline VEP had no influence on RCL and RCA. ONs during the observational period led to mean RCL and RCA of +11.689 ms/y (n = 16 eyes; SD = 17.593; p = 0.003) and -1.238 µV/y (n = 11 eyes; SD = 3.708; p = 0.308), respectively. This first longitudinal VEP study of patients with NMOSD provides evidence of progressive VEP latency delay occurring independently of acute ON. Prospective longitudinal studies are needed to corroborate these findings and help to interpret the clinical relevance.

Evaluation of optic nerve functions in subacute combined degeneration using visual evoked potential and diffusion tensor imaging-a pilot study.

To evaluate optic nerve involvement in subacute combined degeneration (SACD) using diffusion tensor imaging (DTI) and visual evoked potential (VEP) studies, and their changes following cobalamine treatment. Six patients with SACD and six healthy matched controls were included. Visual acuity, fieldof vision, and color vision were tested. Pattern shift VEP was done, and P100 latency and amplitude were measured. Optic nerve MRI, and DTI of optic nerve to muscle ratio were measured, and fractional anisotropy ratio (FAR), axial diffusivity ratio (ADR), radial diffusivity ratio (RDR), and mean diffusivity ratio (MDR) were calculated. The patients received hydroxyl cobalamine 1000 µg intramuscularly and their clinical examination, VEP and DTI studies were repeated at 3 months. The age of the patients ranged between 16 and 60 years and two were females. Their visual acuity, fieldof vision, and color vision were normal. P100 latency was prolonged in five patients (10 eyes) and amplitude was reduced in one (1 eye). The SACD patients had reduced FAR (1.94 ± 0.55 vs 2.81 ± 0.42; p = 0.01) and increased MDR (1.00 ± 0.04 vs 0.95 ± 0.01; p = 0.01) and RDR (0.96 ± 0.03 vs 0.89 ± 0.01; p = 0.002) compared to the controls. The FAR value correlated with P100 latency (r = -0.88). At 3 months, FAR value increased which was associated with improvement in P100 latency. In SACD patients, optic nerve FAR is reduced and correlates with P100 latency. Both these parameters improve on cobalamine treatment. Subclinical VEP abnormalities are common in SACD but conventional MRI sequence of optic nerve is normal. DTI of optic nerve reveals reduced fractional anisotropy (FA) values which improve after cobalamine treatment. FA values correlate with prolongation of P100 latency. DTI and VEP abnormalities suggest subclinical optic nerve myelin dysfunction.

S105. Effect of change in pattern stimulation on the response latencies and amplitude of visual evoked potential in migraneurs and normal healthy adults

Visual Evoked Potentials (VEPs) are non- invasive studies which measure the electrophysiological activity at visual cortex. It represents the functional activity of optic pathway. It represents the functional activity of the optic pathway including anterior segment, retina, optic nerve, optic chiasm, lateral geniculate nucleus and visual cortex. The visual function in migraneurs differs from normal subjects and studies of VEP in migraneurs have yielded varied results. Several investigators did not find differences between migraneurs and healthy controls. while others reported changes of VEP amplitudes, latencies and habituation response. Thus present study is being conducted to see the variations in VEP latencies and amplitude with different spatial stimulation on pattern reversal VEP in migraineurs and healthy adults. A case control study is being conducted enrolling 250 migraine patients and 250 controls of either gender after having a written informed consent. VEP recording on a 6 channel EMG/EP measuring system of Nihon kohden is being done on all participants. Responses are recorded from scalp by electrodes placed according to the International 10/20 system. Visual stimulation is done with checkerboard pattern generated on the monitor consisting of black and white checks whose phase reverse with spatial frequency rates 0.5, 1, 2 and 4 cycles per degree and pattern size 16 × 16, 32 × 32, 64 × 64, 128 × 128, 256 × 256. 100 stimuli are given for each combination of pattern and frequency and an interval of at least 3 min is allowed between two patterns of stimulations. Preliminary analysis of data of 60 patients and 60 controls collected till now was analysed by clubbing the waveforms having the similar frequencies but different checkerboard size. It was seen that the onset latency, N75 was significantly different with smaller check size, i.e. 64 × 64 and 128 × 128 at all the frequencies 0.5,Hz,1 Hz, 2 Hz and 4 Hz. N75 latency was significantly different also at 4 Hz frequency and checkerboard 32 × 32. P100 latency showed significant differences only with smallest check size (128 × 128) at extremes of frequencies used i.e. 0.5 Hz and 4 Hz. While N145 latencies did not show any difference with any combinations of frequencies and checkerboard size. In the light of initial observations and preliminary analysis, it is prudent to include more participants in the study for increasing the power especially for the results which are showing borderline significance. This will assign more objectivity to finding. Probably migraineurs have different response to extreme visual stimuli than non-migraineurs thus we plan to summarize the data with mean as measure of central tendency and standard deviation as measure of dispersion. The clubbed data will be compared for specified latency and amplitude by applying the repeated measure ANOVA (RANOVA). In the next step we intend to do a linkage analysis for two groups for identifying the pattern (if any).

Does Rifaximin Improve EEG and VEP in Egyptian Cirrhotic Patients with Minimal Hepatic Encephalopathy?

Background: Minimal hepatic Encephalopathy (MHE) is defined as HE without symptoms on clinical/neurological examination, but with deficits in some cognitive areas that can only be measured by neuropsychometric testing. However, numerous studies have shown that, although the neurological symptoms are slight, affected patients are markedly impaired in their quality of life and ability to work. Various treatment modalities that have been shown to reverse MHE include lactulose/lactitol, probiotics/synbiotics, L-carnitine but rifaximin has shown a general trend toward better efficacy and better tolerability in patients with overt hepatic encephalopathy (OHE). Objective: Our objective is to assess the diagnostic role of minimental state examination (MMSE), electroencephalography (EEG) and visual evoked potential (VEP) in detection of MHE and to evaluate the efficacy of rifaximin in improving EEG and VEP in patients with MHE. Patients and Methods: Sixty cirrhotic patients were enrolled in the study depending on clinical evidence of stigmata of chronic liver disease, laboratory investigations including liver function tests, ultrasonographic features of liver cirrhosis and with no evidence of overt hepatic encephalopathy. Diagnois of MHE was made depending on minimental state examination (MMSE) and neurophysiological tools including EEG and VEP. A control group of sixty healthy volunteers with age and sex matched were included. The patient group received Rifaximin 550 mg twice daily for 8 weeks then follow up EEG and VEP studies were done. Results: MHE was detected in 36.7%, 48.3%, 51.7% of our series based on MMSE, EEG and VEP respectively. Child Pouph A, B, C was found in 51.7%, 35%, 13.3% respectively. Rifaximin was well tolerated. At the end of treatment, EEG and VEP studies were done which showed signficant changes between pre and post treatment results (P value = 0.03, 0.001, Conclusion: MMSE as well as EEG and VEP were reasonable diagnostic tools for early detection of MHE particularly in countries with low level of education. Rifaximin significantly improves both EEG and VEP in cirrhotic patients with MHE.

Visual Evoked Potential in Children With Developmental Disorders: Correlation With Neurodevelopmental Outcomes.

ObjectiveTo investigate the neurodevelopmental outcomes in children with developmental disorder according to visual evoked potential (VEP) results.MethodsWe retrospectively analyzed children who visited our Department of Pediatric Rehabilitation Medicine with a chief complaint of developmental disability from January 2001 to July 2015. Of the 549 medical records reviewed, 322 children younger than 42 months who underwent both Bayley Scales of Infant and Toddler Development second edition (BSID-II) and VEP studies were enrolled. We compared the development of 182 children with normal VEP latency and 140 children with delayed VEP latency results using the BSID-II results. The Mann-Whitney U-test was used to analyze the differences between the two groups.ResultsThere were no significant differences in baseline characteristics between the two groups. The delayed VEP latency group showed a significant delay in BSID-II index scores and developmental quotients compared with the normal VEP latency group. In addition, a comparative analysis of developmental quotients of mental and psychomotor domains according to age (younger than 12 months, 12–23 months, and 24–42 months) revealed significantly lower values in children with delayed VEP latency compared to children with normal VEP latency, younger than 12 months and from 12 to 23 months.ConclusionChildren with delayed VEP latency showed more developmental delay than children with normal VEP latency. It is suggested that VEP can be easily applied to children with suspected developmental delay when physicians have concerns about visual impairment. Furthermore, it is proposed that VEP results could provide an insight into children's development and serve as early indicators for consultation with an ophthalmologist for the existing problem.

The abnormal bifid W-waveform visual evoked potential early indicated of demyelination optic neuritis is a primary sign of multiple sclerosis disease

Objective: Multiple sclerosis (MS) is the inflammatory demyelinating process resulting in the episodic neurological dysfunction, involvement of the retinal pathway in the form of optic neuritis. These are clinical causes of ophthalmic symptoms, such as the blurring of vision, impaired of vision, and some cases are silent and the visual evoked potential (VEP) may be beneficial if there is abnormality along the optic tract.Methods: A total of 20 elected patients with MS compared with 15 healthy control groups. All groups in the present study conducted by the reversal pattern of VEP test for both eyes identify the N75-P100-N145 parameters and the percentage of the bifid W-waveform recorded in VEP.Results: The VEPs study recorded the highly significant difference in comparing between the patients and the control group; we found the significant difference (<0.005) in latency of N75, P100, N145 and N75/P100 amplitude in both eyes. The bifid W-waveform of abnormal VEP recorded in 65% of patients, 45% of the patients had bifid changes in both eyes and 20% of patients had changes in the left eye. These changes of waveform ship had a significant relationship to loss of amplitude but not related to prolong of P100 latency.Conclusion: The bifid W-shape waveform in abnormal VEP indication in early diagnosis the demyelination lesions of the optic pathway in patients with clinical and subclinical ophthalmic manifestation, a primary sign of MS diseases.

Connectopathy in Autism Spectrum Disorders: A Review of Evidence from Visual Evoked Potentials and Diffusion Magnetic Resonance Imaging.

Individuals with autism spectrum disorder (ASD) show superior performance in processing fine details; however, they often exhibit impairments of gestalt face, global motion perception, and visual attention as well as core social deficits. Increasing evidence has suggested that social deficits in ASD arise from abnormal functional and structural connectivities between and within distributed cortical networks that are recruited during social information processing. Because the human visual system is characterized by a set of parallel, hierarchical, multistage network systems, we hypothesized that the altered connectivity of visual networks contributes to social cognition impairment in ASD. In the present review, we focused on studies of altered connectivity of visual and attention networks in ASD using visual evoked potentials (VEPs), event-related potentials (ERPs), and diffusion tensor imaging (DTI). A series of VEP, ERP, and DTI studies conducted in our laboratory have demonstrated complex alterations (impairment and enhancement) of visual and attention networks in ASD. Recent data have suggested that the atypical visual perception observed in ASD is caused by altered connectivity within parallel visual pathways and attention networks, thereby contributing to the impaired social communication observed in ASD. Therefore, we conclude that the underlying pathophysiological mechanism of ASD constitutes a “connectopathy.”

The Development and Aging of the Magnocellular and Parvocellular Visual Pathways as Indicated by VEP Recordings between 5 and 84 Years of Age.

It is well known that pattern reversal visual evoked potentials (VEPs) are age-sensitive. Through the use of this technique, it is possible to assess both of the major visual pathways (i.e., the magnocellular and parvocellular ones) in terms of function and development. What developmental path these pathways follow, and if they develop/age in parallel across the human lifespan is a matter of ongoing debate, yet, only a few VEP studies have dealt with this issue. This cross-sectional study examined a sample of 115 healthy volunteers aged 5 to 84 years. Beyond the standard checkerboard pattern reversal stimulation at 97% contrast, we recorded pattern-reversal VEPs at 6% contrast to selectively stimulate the M pathway and isoluminant red and green checkerboard stimulation was also used to selectively stimulate the P pathway. Our results do not support the developmental advantage of any of the pathways. The development of both pathways appear to take a remarkably long time (well into the 30s), and the signs of aging become marked over 50 years of age, especially in the case of the magnocellular pathway.

Reliability of VEP Recordings Using Chronically Implanted Screw Electrodes in Mice.

Visual evoked potentials (VEPs) are widely used to objectively assess visual system function in animal models of ophthalmological diseases. Although use of chronically implanted electrodes is common in longitudinal VEP studies using rodent models, reliability of recordings over time has not been assessed. We compared VEPs 1 and 7 days after electrode implantation in the adult mouse. We also examined stimulus-independent changes over time, by assessing electroencephalogram (EEG) power and approximate entropy of the EEG signal. Stainless steel screws (600-μm diameter) were implanted into the skull overlying the right visual cortex and the orbitofrontal cortex of adult mice (C57Bl/6J, n = 7). Animals were reanesthetized 1 and 7 days after implantation to record VEP responses (flashed gratings) and EEG activity. Brain sections were stained for glial activation (GFAP) and cell death (TUNEL). Reliability analysis, using intraclass correlation coefficients, showed VEP recordings had high reliability within the same session, regardless of time after electrode implantation and peak latencies and approximate entropy of the EEG did not change significantly with time. However, there was poorer reliability between recordings obtained on different days, and a significant decrease in VEP amplitudes and EEG power. This amplitude decrease could be normalized by scaling to EEG power (within-subjects). Furthermore, glial activation was present at both time points but there was no evidence of cell death. These results indicate that VEP responses can be reliably recorded even after a relatively short recovery period but decrease response peak amplitude over time. Although scaling the VEP trace to EEG power normalized this decrease, our results highlight that time-dependent cortical excitability changes are an important consideration in longitudinal VEP studies. This study shows changes in VEP characteristics over time in chronically implanted mice. Thus, future preclinical longitudinal studies should consider time in addition to amplitude and latency when designing and interpreting research.

A VEP study in sleeping and awake one-month-old infants and its relation with social behavior

With the present study we aimed to analyze the relationship between infants’ behavior and their visual evoked-potential (VEPs) response. Specifically, we want to verify differences regarding the VEP response in sleeping and awake infants and if an association between VEP components, in both groups, with neurobehavioral outcome could be identified. To do so, thirty-two full-term and healthy infants, approximately 1-month of age, were assessed through a VEP unpatterned flashlight stimuli paradigm, offered in two different intensities, and were assessed using a neurobehavioral scale. However, only 18 infants have both assessments, and therefore, these is the total included in both analysis. Infants displayed a mature neurobehavioral outcome, expected for their age. We observed that P2 and N3 components were present in both sleeping and awake infants. Differences between intensities were found regarding the P2 amplitude, but only in awake infants. Regression analysis showed that N3 amplitude predicted an adequate social interactive and internal regulatory behavior in infants who were awake during the stimuli presentation. Taking into account that social orientation and regulatory behaviors are fundamental keys for social-like behavior in 1-month-old infants, this study provides an important approach for assessing physiological biomarkers (VEPs) and its relation with social behavior, very early in postnatal development. Moreover, we evidence the importance of the infant’s state when studying differences regarding visual threshold processing and its association with behavioral outcome.

Steady-state visual-evoked response to upright and inverted geometrical faces: A magnetoencephalography study

The face is one of the most important visual stimuli in human life, and inverted faces are known to elicit different brain responses than upright faces. This study analyzed steady-state visual-evoked magnetic fields (SSVEFs) in eleven healthy participants when they viewed upright and inverted geometrical faces presented at 6Hz. Steady-state visual-evoked responses are useful measurements and have the advantages of robustness and a high signal-to-noise ratio. Spectrum analysis revealed clear responses to both upright and inverted faces at the fundamental stimulation frequency (6Hz) and harmonics, i.e. SSVEFs. No significant difference was observed in the SSVEF amplitude at 6Hz between upright and inverted faces, which was different from the transient visual-evoked response, N170. On the other hand, SSVEFs were delayed with the inverted face in the right temporal area, which was similar to N170 and the results of previous steady-state visual-evoked potentials studies. These results suggest that different mechanisms underlie the larger amplitude and delayed latency observed with face inversion, though further studies are needed to fully elucidate these mechanisms. Our study revealed that SSVEFs, which have practical advantages for measurements, could provide novel findings in human face processing.