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Purpose: To study the effect of refractive errors on pattern visual evoked potential (VEP) recordings in the pediatric population. Methods: This cross?sectional observational study assessed 240 eyes of 120 participants attending the outpatient department of a tertiary care center in North India. Participants were between 8 and 18 years of age; 30 participants each were recruited into four groups, namely emmetropia, myopia, hypermetropia, and amblyopia. They were then subjected to pattern reversal VEP, with P?100 amplitude and latency recorded for each participant. Results: The emmetropic group in this study provided normal values of P?100 parameters, namely P?100 latency and P?100 amplitude with readings of 115.78 ± 10.19 ms and 11.11 ± 4.08 ?V, respectively. P?100 amplitude was significant compared to P?100 latency in detecting the presence or absence of a specific type of refractive error. It was found that there was a significant association between severity of myopia and P?100 latency (both unaided and aided) with P < 0.05. The severity of hypermetropia showed a significant association with P?100 amplitude (unaided) (P < 0.05). Receiver operating characteristics analysis revealed P?100 amplitude to be a good predictor of refractive error and the cut?offs were calculated. Conclusion: The P?100 parameters of the pediatric Indian population were comparatively higher than conventional values. P?100 latency seemed to better correlate with myopia, while hypermetropia correlated with P?100 amplitude. P?100 amplitude appears to be the most significant predictor of the presence of refractive error in an individual.
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Background: Visual Evoked Potentials (VEPs) was studied in asymptomatic Human Immunodeficiency Virus (HIV) positive persons and corresponding controls to detect subclinical visual system involvement in the early stage of HIV. Aim and Objectives: To study VEPs in asymptomatic HIV-positive persons and corresponding controls. Materials and Methods: In this study,100 participants in the age group 25–45 years were recruited, fifty were HIV positive and asymptomatic (CD4 count >350 cells/mm3) and were not on Anti-Retroviral Treatment, and 50 were healthy age-matched individuals who were HIV negative. Results: P 100 latency was significantly prolonged in the study group than in the control group. No significant difference was observed between the control group and study group for the amplitude of VEP. Conclusion: Study of VEPs in asymptomatic HIV positive persons suggests subclinical visual nervous system involvement in early stages of HIV, as evidenced by prolonged P 100 latency. Hence, VEPs is important to detect subclinical nervous system involvement in the early stages of HIV.
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Para evaluar los procesos atencionales a estímulos visuales que no requieren repuesta motora, se llevó a cabo un estudio con potenciales evocados a 17 niños con trastornos del déficit de atención/ hiperactividad (TDAH-I) con predominio inatento y a 15 controles de edades entre 7 y 11 años. Se analizó la latencia y localización de fuentes de los potenciales evocados visuales tempranos P100 y N100 durante la realización de una tarea oddball visual (20% rayas horizontales y 80% verticales) en que las rayas verticales no exigían respuesta motora. Los resultados indican que los niños con TDAH-I procesan la información visual que no requiere respuesta motora con un mayor aumento de la actividad cerebral y mediante la vía temporal ventral mientras que el grupo control lo hace mediante la vía parietal dorsal. Este proceso neurobiológico de procesamiento de la información visual vía temporal ventral de los niños con TDAH-I podría deberse a alteraciones en los procesos emocionales que influyen directamente en el reconocimiento visual o a un déficit en el control de los procesos atencionales por parte de la vía parietal dorsal.
To evaluate attentional processes to visual stimuli that do not require motor response, a study with evoked potentials was carried out on 17 children with attention deficit disorder predominantly inattentive (ADDH-I) and 15 controls between the ages of 7 and 11 years. The latency and localization of sources of the early visual evoked potentials P100 and N100 were analyzed during the performance of a visual oddball task (20% horizontal and 80% vertical lines) where the vertical lines did not require motor response. The results indicate that ADDH-I group process visual information that does not require motor response with a greater increase in brain activity and through the ventral temporal pathway, while the control group does so by means of the dorsal parietal stream. This neurobiological process of visual information processing by ventral temporal pathway of ADDH-I group could be due to alterations in emotional processes that directly influence visual recognition or as consequence of deficit in the control of attentional processes by the dorsal parietal pathway.
Subject(s)
Humans , Male , Female , Child , Attention Deficit Disorder with Hyperactivity/physiopathology , Evoked Potentials, Visual/physiology , Parietal Lobe/physiology , Attention/physiology , Temporal Lobe/physiology , Visual Perception/physiology , Electroencephalography , Evoked Potentials/physiologyABSTRACT
Objective To research the correlation between the visual acuity ratio and pattern reversal visual evoked potential （PRVEP） P100 waveform amplitude ratio of both eyes. Methods Forty-seven volunteers were selected, and the visual chart visual acuity of both eyes was measured. The visual acuity ratio of the eye with poor vision to the eye with better vision was calculated by five grade notation method. The amplitudes of P100 waveforms of both eyes were recorded respectively by using black-and-white checkerboard PRVEP and chosing 1°, 15' stimulating visual angle, and the ratio of amplitudes between the two eyes was also calculated. SPSS 20.0 software was used to analyze the correlation between the visual acuity ratio and the ratio of P100 waveform amplitudes between the two eyes. Return test and linear regression analysis with the binocular ratio of P100 waveform amplitudes as the independent variable （x） and the binocular visual acuity ratio as the dependent variable （y） were made. Results There was a positive correlation between the binocular visual acuity ratio and the ratio of P100 waveform amplitudes under 15' stimulating visual angle （Pearson correlation coefficient was 0.62, P=0.000）. The fitting linear regression equation was y=0.090 x+0.846 （F=20.954, P=0.000）. There was no significant correlation between the binocular ratio of visual acuity and the binocular ratio of P100 waveform amplitudes under 1° stimulating visual angle （P>0.05）. Results of return test showed that there was no statistical significance in the difference between visual acuity estimated by equation and actual detected visual acuity. Conclusion In forensic appraisal of monocular injury, fitting linear regression equation of binocular visual acuity ratio and the binocular ratio of P100 waveform amplitudes under 15' stimulating visual angle, is helpful for visual acuity level estimation of the injured eye to some extent.
Subject(s)
Humans , Evoked Potentials, Visual , Eye/physiopathology , Regression Analysis , Vision, Ocular , Visual AcuityABSTRACT
The complex multidimensional visual patterns of facial expression is particularly well sui ted for studying perception and the processes underlying perceptual integration of component parts into a meaningful whole.With the high resolution in milliseconds,event-related potential (ERP) may be an excellent technique to track the time course of cognitive processing for facial emotions.Facial affective stimuli elicit particular ERP components involved in early processing of facial expressions,including:early sensory processing of visual stimuli:the P100;early structural encoding of facial features:the N170;second-order sustained activities necessary for consequent deeper processing:the posterior P2 and decoding of facial features to identify emotional content:the N250.We reviewed above mentioned ERP components respectively,in order to add the knowledge about ERP components as indicators of neural dynamics of facial emotion processing,and to provide a point of reference for further exploration on facial emotion processing that may be useful for understanding human cognition development and pathology.
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Glaucoma is a chronic, progressive bilateral optic neuropathy which disturbs the structural or functional integrity of the optic nerve that causes characteristic atrophic changes in it, which leads to specific visual field defects over time with loss of visual function. Primary open angle glaucoma (POAG) is the most common form of glaucoma in India and is fast emerging as a major cause of bilateral blindness. This rural hospital based study was conducted to evaluate whether glaucomatous visual field defects particularly the mean defect of Humphrey visual field could be related to VEP parameters of patients having POAG. Visual field by Humphrey perimeter and simultaneous recordings of pattern reversal visual evoked potential (PRVEP) were assessed in 100 patients with POAG. There was a significant (P<0.05) negative correlation of P100 latency, N155 latency and P100 duration and a highly significant (P<0.001) positive correlation of P100 amplitude with mean deviation (index of global visual field damage, MD) of Humphrey visual field in the subjects of POAG in various age groups. N70 latency showed a non-significant positive correlation with MD. The VEP changes observed by us in POAG patients were consistent with the progressing mean defect quantitatively. Therefore, it can be concluded that the VEP parameters can be useful quantitative indices in the evaluation of glaucomatous visual function damage.
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This study explored the accuracy of using visual evoked potentials (VEP) technology for visual acuity estimation. The enrolled 726 patients with post-traumatic unilateral decrease in visual acuity included the injured eyes served as the experimental group, and the healthy eyes as the control group. The least signal visual angle (LSVA), and amplitude and latency of P100 were chosen as test indexes. The results under different experimental conditions were recorded by PRVEP technology. All data collected were processed and analyzed by SPSS software. The results showed that the coincidence between subjective and VEP visual acuity was 96.7% in control group, but there was very significant difference in experimental group. It was concluded that with the regression formulation for the amplitude of P100 and vision under LSVA, visual acuity can be estimated more accurately and impartially.
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PURPOSE: This study was conducted to investigate the role of the pattern visual evoked potential (pVEP) as a predictor of occlusion therapy for patients with strabismic, anisometropic, and isometropic amblyopia. The secondary aim was to compare the characteristics of pVEP between strabismic and anisometropic amblyopia. METHODS: This retrospective comparative case series included 120 patients who had received occlusion therapy or a glasses prescription for correction of strabismic, anisometropic, and isometropic amblyopia (20 patients had strabismic amblyopia, 41 patients had anisometropic amblyopia, and 59 patients had isometropic amblyopia). For each patient, the value of the P100 latency on pVEP at the time of the initial diagnosis of amblyopia was collected. Subsequently, the P100 latency was compared according to types of amblyopia. Fifty of 120 patients (7 patients with strabismic amblyopia, 21 patients with anisometropic amblyopia, and 22 patients with isometropic amblyopia) who were followed-up for longer than 6 months were divided into two groups based on the value of their P100 latency (Group 1, P100 latency 120 msec or less; Group 2, P100 latency longer than 120 msec.) The amount of visual improvement after occlusion therapy or glasses was compared between two study groups. RESULTS: The mean P100 latency was 119.7+/-25.2 msec in eyes with strabismic amblyopia and 111.9+/-17.8 msec in eyes with non-strabismic (anisometropic or isometropic) amblyopia (p=0.213). In Group 1, the mean visual improvement after occlusion therapy or glasses was 3.69+/-2.14 lines on Dr. Hahn's standard test chart; in Group 2, the mean improvement was 2.27+/-2.21 lines (p=0.023). CONCLUSIONS: The P100 latency on pVEP at the time of initial diagnosis was significantly related to the visual improvement after occlusion therapy or glasses in patients with strabismic, anisometropic, and isometropic amblyopia. Therefore, it was presumed that patients with a delayed P100 latency might have less visual improvement after occlusion therapy or glasses. In addition, there was no apparent difference in P100 latency between patients with strabismic and non-strabismic (anisometropic or isometropic) amblyopia.
Subject(s)
Adolescent , Child , Child, Preschool , Female , Humans , Male , Amblyopia/physiopathology , Anisometropia/physiopathology , Evoked Potentials, Visual/physiology , Retrospective Studies , Sensory Deprivation , Strabismus/physiopathology , Treatment Outcome , Visual AcuityABSTRACT
The early stages of visual information processing, involving the detection and perception of simple visual stimuli, have been demonstrated to be sensitive to psychotropic agents. The present study investigated the effects of an acute dose of bromazepam (3 mg), compared with placebo, on the P100 component of the visual evoked potential and reaction time. The sample, consisting of 14 healthy subjects (6 male and 8 female), was submitted to a visual discrimination task, which employed the "oddball" paradigm. Results suggest that bromazepam (3 mg) impairs the initial stage of visual information processing, as observed by an increase in P100 latency.
Os estágios iniciais do processamento da informação visual, envolvendo a percepção e detecção de um estímulo visual simples, tem demonstrado serem sensíveis a agentes psicotrópicos. O presente estudo investigou os efeitos de uma dose aguda de bromazepam (3 mg), comparado com placebo, no componente P100 do potencial evocado visual e no tempo de reação. A mostra consistiu de 14 sujeitos sadios (6 homens e 8 mulheres), submetidos a uma tarefa de discriminação visual, a qual empregou o paradigma "oddball". Os resultados sugerem que o bromazepam (3 mg) prejudica o estágio inicial do processamento da informação visual, como observado pelo aumento da latência do P100.
Subject(s)
Adult , Female , Humans , Male , Anti-Anxiety Agents/pharmacology , Bromazepam/pharmacology , Evoked Potentials, Visual/drug effects , Analysis of Variance , Electrophysiology , Evoked Potentials, Visual/physiology , Placebos , Reaction Time/drug effectsABSTRACT
OBJECTIVE: Multiple factors including age, sex, habituation, refraction, cooperation and technical variables are associated with P100 latency of Visual evoked potential (VEP). So we tried to evaluate the P100 latency of visual evoked potential according to refraction. METHOD: We studied 28 patients (12 males, 16 females) with myopia. Subjects were divided into 3 groups (mild, moderate, severe myopia) according to refraction and we evaluated the results of VEP studies. RESULTS: Mean values of refraction and latency (P100) of naked eyes were -4.27 D, 103.95 msec. and those of corrected eyes (in glasses) were -0.25 D, 100.59 msec. Respectively, in mild, moderate and severe myopia, the each P100 latency of naked eyes were 101.27 msec, 102.59 msec, 107.99 msec and those of corrected eyes were 98.33 msec, 100.58 msec, 102.19 msec respectively (p<0.05). There was significant negative correlation between refraction and P100 latency in myopia. CONCLUSION: Our results suggested that there were significant changes in VEP (P100 latency) according to refraction. In performing the VEP study, we should consider the refraction and visual acuity.
Subject(s)
Humans , Male , Evoked Potentials, Visual , Myopia , Visual AcuityABSTRACT
OBJECTIVE: Absolute or relative increase in the latency of the major surface positive component is almost invariably found in patients with demyelination optic neuropathy. Using the pattern- reversal method, our study illustrates the significant changes in the latency of the P100 component when refractive errors are introduced to defocus in normal person. METHOD: Four women and ten men aged 20 to 27 years were selected after a thorough ophthalmological assessment. Visual acuity (VA) was 6/6 or better in all subject and none had dyschromatopsia or significant astigmatism. Refractive errors were created by the combined standard lenses. RESULTS: The mean value of P100 latency were as follows: 93.74 +/- 3.30 msec, naked eyes; 98.14 +/- 7.37 msec, the +2/+x 90 lens; 96.50 +/- 3.76 msec, the +1/ +1 x90 lens; 94.55 +/- 4.20 msec, the -1/ -1x90; 96.29 +/- 2.88 msec, the -2/ -2 x90 lens. The P100 latencies showed singnificant standard lens except with -1/ -1 x90 lens. The P100 latency was prolonged according to the progression of refractive error. CONCLUSION: Because a relative or absolute prolongation of P100 latency is often found in cases of suspected multiple sclerosis, and because of their similarity to the findings of our study, we would emphasize that refractive errors should be reduced or eliminated to minimize the false-positive results.
Subject(s)
Female , Humans , Male , Astigmatism , Demyelinating Diseases , Evoked Potentials, Visual , Multiple Sclerosis , Optic Nerve Diseases , Refractive Errors , Visual AcuityABSTRACT
Objective:To setup a stable cell line which can overexpress human p100 protein,and then st udy the physiologic functions of p100 in regulation of STAT6-mediated gene tran scription.Methods:Using coimmunoprecipitation method to identify protein-protein interactions.STA T6-mediated gene transcriptional activation was detected by luciferase assay.Results:Human p100 protein interacted with both STAT6 and RNA polymerase Ⅱ,resulting in the enhancement of STAT6-mediated gene transcriptional activation.Conclusion:Human p100 protein acts as a bridging factor between STAT6 and basal transcripti onal machenary. [
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Event-related potentials (ERPs) were recorded from 9 normal subjects engaged in a somatosensory target discrimination task. Subjects were instructed (1) to keep a mental count of each target or (2) to rotate a grip in the direction of abduction after each target stimulus using the right hand. Target stimuli were electrical pulses delivered randomly through ring electrodes to the left second digit with probabilities of 0.2, and nontarget stimuli were delivered to the left fifth digit with probabilities of 0.8.<BR>P 100 was prominent in somatosensory tasks, and had a widespread distribution on the scalp without having any relation to kinds of tasks, therefore, P 100 reflects the sensation of somatosensory stimulation. N 140 was largest at Fz in both counting and movement tasks, so our result supported the hypothesis that N 140 is generated in the frontal lobes regions. Moreover, N 140 latency was shorter during movement than during counting. These results indicate that N 140 is related to carrying out movement. P 300 was largest at Cz during counting, and largest at Pz and C4' during movement. These results also indicate that P 300 may have multiple intracerebral generators since P300 origin differs based on the kind of tasks or stimuli. In addition, the appearance of P300 after nontarget stimuli indicates that P 300 reflects a non-selective postdecision closure of cognitive activity. In conclusion, each component of ERPs may have a specific origin and specific characteristics.
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The Flash Light Emitted Diode Flash Visual Evoked Potential(Flash VEP) is useful when patients are unable to cooperate sufficiently for a Pattern Reversal Visual Evoked Potential(RP-VEP). In order to evaluate the clinical utility of Flash VEP, we performed the PR-VEP and Flash VEP in 208 eyes of 104 normal persons. The average P100 latency(LaP100) was analyzed according to check size, age, sex, and the laterality of the eye. The LaP100 of PR-VEP stimulated with 8 X 8(120' X 96'), 16 X 16(60' X 48'), 32 X 32 (30' X 24') and 64 X 64(15' X 12') check size were 98.88 +/- 7.57msec(mean S.D msec) , 97.68 +/- 7.44msec, 96.31 +/- 7.21msec, 101.20 +/- 7.81msec, respectively. The LaP100 of PR-VEP stimulated with 32 X 32 check size at 3rd, 4th, 5th, 6th and 7th decades were 93.95 +/- 5.61msec, 94.70 +/- 7.71msec, 92.92 +/- 6.28msec, 97.78 +/- 6.24 msec, 102.79 +/- 5.27msec, respectively. The LaP100 of PR-VEP remained relatively stable until over 6th decade when it increased significantly (p0.05), and between male and female(p>0.05) in the LaP100 of both VEP. These results showed that LaP100 of PR-VEP changes according to the check size and patient's age. We should interprete the LaP100 of PR-VEP or Flash VEP after the processing of averaging its P100 according to the patient's.