Role of visual evoked potential as a window to detect functional changes that occur without signs of diabetic retinopathy in fundoscopy: Case series involving symptomatic overt diabetic pregnant women

Diabetic retinopathy (DR) is a microvascular complication associated with diabetes mellitus. Pregnancy is a major risk factor for DR in diabetic women. Recent evidenced suggests that in course of DR functional changes including damage of pre-ganglionic and ganglionic cells in retina precede structural microvascular changes. A number of studies in the past have highlighted the role of pattern visual evoked potential (VEP) in detecting such functional changes. However, the study of VEP changes in diabetic pregnancies remains unexplored. This case series has the objective of exploring VEP changes in symptomatic OVD cases, who had no signs of DR on fundoscopy. We present two cases of overt diabetic women who complaint of straining of eyes, headache, and difficulty in reading during pregnancy. Complete ophthalmic examination was done in both the cases followed by a VEP test. VEP test was done as a part of a research project. The ethical clearance for the project was obtained from the Institute’s Ethics Committee before the commencement of the study. Fundoscopic examination in both cases revealed that the retina was within normal limits with no signs of retinopathy. In Case 1, P100 latency was increased for the left eye and was normal for the right eye during the first visit. While P100 latency was increased for both left and right eye during the second visit. There was a substantial increase in P100 latency for both eyes in second visit as compared to first visit. In Case 2, P100 latency was increased for both left and right eye and amplitude decreased for the left eye. This is a case series consisting of symptomatic overt diabetic pregnant women who had increased P100 latency despite no signs of retinopathy in fundoscopy. The previous studies have reported that multiple follow-ups with ophthalmoscopy may not be cost-effective in diabetic pregnant women. VEP provides a window for detection of early functional changes that may help identify at risk patients for follow-up and early intervention.

Advances in brain-computer interface based on high-frequency steady-state visual evoked potential / 生物医学工程学杂志

Steady-state visual evoked potential (SSVEP) has been widely used in the research of brain-computer interface (BCI) system in recent years. The advantages of SSVEP-BCI system include high classification accuracy, fast information transform rate and strong anti-interference ability. Most of the traditional researches induce SSVEP responses in low and middle frequency bands as control signals. However, SSVEP in this frequency band may cause visual fatigue and even induce epilepsy in subjects. In contrast, high-frequency SSVEP-BCI provides a more comfortable and natural interaction despite its lower amplitude and weaker response. Therefore, it has been widely concerned by researchers in recent years. This paper summarized and analyzed the related research of high-frequency SSVEP-BCI in the past ten years from the aspects of paradigm and algorithm. Finally, the application prospect and development direction of high-frequency SSVEP were discussed and prospected.

The Value of VR-PVEP in Objective Evaluation of Monocular Refractive Visual Impairment / 法医学杂志

OBJECTIVES@#To study the virtual reality-pattern visual evoked potential (VR-PVEP) P100 waveform characteristics of monocular visual impairment with different impaired degrees under simultaneous binocular perception and monocular stimulations.@*METHODS@#A total of 55 young volunteers with normal vision (using decimal recording method, far vision ≥0.8 and near vision ≥0.5) were selected to simulate three groups of monocular refractive visual impairment by interpolation method. The sum of near and far vision ≤0.2 was Group A, the severe visual impairment group; the sum of near and far vision <0.8 was Group B, the moderate visual impairment group; and the sum of near and far vision ≥0.8 was Group C, the mild visual impairment group. The volunteers' binocular normal visions were set as the control group. The VR-PVEP P100 peak times measured by simultaneous binocular perception and monocular stimulation were compared at four spatial frequencies 16×16, 24×24, 32×32 and 64×64.@*RESULTS@#In Group A, the differences between P100 peak times of simulant visual impairment eyes and simultaneous binocular perception at 24×24, 32×32 and 64×64 spatial frequencies were statistically significant (P<0.05); and the P100 peak time of normal vision eyes at 64×64 spatial frequency was significantly different from the simulant visual impairment eyes (P<0.05). In Group B, the differences between P100 peak times of simulant visual impairment eyes and simultaneous binocular perception at 16×16, 24×24 and 64×64 spatial frequencies were statistically significant (P<0.05); and the P100 peak time of normal vision eyes at 64×64 spatial frequency was significantly different from the simulant visual impairment eyes (P<0.05). In Group C, there was no significant difference between P100 peak times of simulant visual impairment eyes and simultaneous binocular perception at all spatial frequencies (P>0.05). There was no significant difference in the P100 peak times measured at all spatial frequencies between simulant visual impairment eyes and simultaneous binocular perception in the control group (P>0.05).@*CONCLUSIONS@#VR-PVEP can be used for visual acuity evaluation of patients with severe and moderate monocular visual impairment, which can reflect the visual impairment degree caused by ametropia. VR-PVEP has application value in the objective evaluation of visual function and forensic clinical identification.

Objective Assessment of Visual Field Defects Caused by Optic Chiasm and Its Posterior Visual Pathway Injury / 法医学杂志

OBJECTIVES@#To investigate the characteristics and objective assessment method of visual field defects caused by optic chiasm and its posterior visual pathway injury.@*METHODS@#Typical cases of visual field defects caused by injuries to the optic chiasm, optic tracts, optic radiations, and visual cortex were selected. Visual field examinations, visual evoked potential (VEP) and multifocal visual evolved potential (mfVEP) measurements, craniocerebral CT/MRI, and retinal optical coherence tomography (OCT) were performed, respectively, and the aforementioned visual electrophysiological and neuroimaging indicators were analyzed comprehensively.@*RESULTS@#The electrophysiological manifestations of visual field defects caused by optic chiasm injuries were bitemporal hemianopsia mfVEP abnormalities. The visual field defects caused by optic tract, optic radiation, and visual cortex injuries were all manifested homonymous hemianopsia mfVEP abnormalities contralateral to the lesion. Mild relative afferent pupil disorder (RAPD) and characteristic optic nerve atrophy were observed in hemianopsia patients with optic tract injuries, but not in patients with optic radiation or visual cortex injuries. Neuroimaging could provide morphological evidence of damages to the optic chiasm and its posterior visual pathway.@*CONCLUSIONS@#Visual field defects caused by optic chiasm, optic tract, optic radiation, and visual cortex injuries have their respective characteristics. The combined application of mfVEP and static visual field measurements, in combination with neuroimaging, can maximize the assessment of the location and degree of visual pathway damage, providing an effective scheme for the identification of such injuries.

Recognition of high-frequency steady-state visual evoked potential for brain-computer interface / 生物医学工程学杂志

Coding with high-frequency stimuli could alleviate the visual fatigue of users generated by the brain-computer interface (BCI) based on steady-state visual evoked potential (SSVEP). It would improve the comfort and safety of the system and has promising applications. However, most of the current advanced SSVEP decoding algorithms were compared and verified on low-frequency SSVEP datasets, and their recognition performance on high-frequency SSVEPs was still unknown. To address the aforementioned issue, electroencephalogram (EEG) data from 20 subjects were collected utilizing a high-frequency SSVEP paradigm. Then, the state-of-the-art SSVEP algorithms were compared, including 2 canonical correlation analysis algorithms, 3 task-related component analysis algorithms, and 1 task discriminant component analysis algorithm. The results indicated that they all could effectively decode high-frequency SSVEPs. Besides, there were differences in the classification performance and algorithms' speed under different conditions. This paper provides a basis for the selection of algorithms for high-frequency SSVEP-BCI, demonstrating its potential utility in developing user-friendly BCI.

Brain-computer interface coding method based on high-frequency dual-frequency SSVEP / 国际生物医学工程杂志

Objective:To improve the users’ comfort of steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) through high-frequency stimulation and overcome the problem of accuracy decline caused by high frequency by combining dual-frequency encoding.Methods:Two dual-frequency high-frequency 60-instruction paradigms based on left and right visual fields and checkerboard stimuli were designed based on the 25.5 - 39.6 Hz frequency. Thirteen subjects participated in the experiment, and spectrum and spatial characteristics analyses were performed on SSVEP signals. The filter bank parameters were optimized based on the spectrum characteristics. Extended canonical correlation analysis (eCCA), ensemble task-related component analysis (eTRCA), and task-discriminant component analysis (TDCA) were used for SSVEP recognition.Results:Stable SSVEP was successfully induced in both the left and right visual fields and the checkerboard grid paradigm. The left and right visual fields had high signal-to-noise ratios for the fundamental frequency and its harmonics and weak signal-to-noise ratios for intermodulation components, whereas the intermodulation components of the 2 stimulus frequencies of the checkerboard grid, f1 + f2, had significantly higher signal-to-noise ratios than the second harmonic components above 30 Hz, and there was also a f2 ? f1 component and a 2 f1 ? f2 component. Combined with brain topography, it can be seen that the f1 and f2 response components of the left and right visual fields are located on opposite sides of the visual field, while the checkerboard grids are both concentrated in the center of the occipital region. Regarding the lateralization of brain topography amplitude and signal-to-noise ratio, the mean values of the PO3 and PO4 signal-to-noise ratios at the stimulation frequency of the left and right visual fields are consistent with the contralateral response characteristics. The 5 fb ? 1 method is the optimal filter set setting method, and the recognition correctness rate of TDCA for the left and right visual fields is the highest. However, the comparison of the recognition correctness rate of tessellated lattice eTRCA and TDCA is not statistically significant ( P > 0.05). The information transmission rates of the three algorithms all increase and then decrease with the increase in data length. Conclusions:The designed dual-frequency, high-frequency SSVEP-BCI paradigm is able to better balance performance and comfort and provides a basis for practical large instruction set BCI design methods.

Visual function changes of dysthyroid optic neuropathy and ROC curve analysis for early diagnostic indicators / 中南大学学报(医学版)

OBJECTIVES@#Dysthyroid optic neuropathy (DON) is a class of diseases that makes seriously endanger to the vision of patients with thyroid-associated ophthalmopathy. This study aims to observe the visual function changes in patients with DON, and to evaluate the diagnostic value of indicators diagnosing DON.@*METHODS@#A retrospective study was conducted on 98 eyes of 49 patients with dysthyroid optic neuropathy (DON) who were treated in Xiangya Hospital of Central South University from January 2017 to December 2019. All patients were received the examination of best corrected visual acuity (BCVA), Humphrey visual field, visual evoked potential (VEP), and contrast sensitivity. Ninety-eight eyes were divided into a DON group (45 eyes) and a non-DON group (53 eyes). T-test was used to compare the related indicators between the 2 groups. The sensitivity and specificity of each indicator were analyzed by receiver operating characteristic (ROC) curve.@*RESULTS@#The BCVA and visual field index (VFI) of the DON group were significantly lower than those of the non-DON group (all P<0.05). The mean deviation (MD) and pattern standard deviation (PSD) of the DON group were significantly higher than those of the non-DON group (all P<0.05). The low frequency contrast sensitivity (CSL), medium frequency contrast sensitivity (CSM), and high frequency contrast sensitivity (CSH) of the DON group were significantly lower than those of the non-DON group (all P<0.05), with CSH being particularly prominent. Compared with the non-DON group, at spatial frequencies of 15°, 30°, and 60°, the amplitude of N135 wave was significantly reduced, and the latency of N75 wave, P100 wave, and N135 wave was significantly prolonged in the DON group (all P<0.05); at spatial frequencies of 15° and 30°, the amplitude of P100 wave was significantly reduced in the DON group (P<0.05). The ROC curve analysis results showed that the area under the curve (AUC) of VFI, CSL, CSM, CSH and 15° P100 amplitude diagnosing DON were 0.812, 0.841, 0.880, 0.784, and 0.791, respectively, with CSM possessing the highest sensitivity and specificity.@*CONCLUSIONS@#The visual function of patients with DON is decreased. VFI, contrast sensitivity of low, medium, and high frequency, and 15° P100 wave amplitude might be effective indicators for early diagnosis of DON.

Dysthyroid optic neuropathy: Demographics, risk factors, investigations, and management outcomes

Purpose: To analyze the clinical presentations, risk factors, and management outcomes in patients presenting with dysthyroid optic neuropathy (DON). Methods: This is a retrospective, single?center study carried out on consecutive patients presenting with DON over a period of 4 years (2013–2016). The VISA classification was used at the first visit and subsequent follow?ups. The diagnosis was based on optic nerve function tests and imaging features. Demographic profiles, clinical features, risk factors, and management outcomes were analyzed. Results: Thirty?seven eyes of 26 patients diagnosed with DON were included in the study. A significant male preponderance was noted (20, 76.92%). Twenty patients (76.9%, P = 0.011) had hyperthyroidism, and 15 (57.69%, P = 0.02) were smokers. Decreased visual acuity was noted in 28 eyes (75.6%). Abnormal color vision and relative afferent pupillary defects were seen in 24 (64.86%) eyes, and visual field defects were seen in 30 (81.01%) eyes. The visual evoked potential (VEP) showed a reduced amplitude in 30 (96.77%, P = 0.001) of 31 eyes and delayed latency in 20 (64.51%, P = 0.0289) eyes. Twenty?six (70.27%) patients were treated with intravenous methyl prednisolone (IVMP) alone, whereas 11 (29.72%) needed surgical decompression. The overall best?corrected visual acuity improved by 0.2 l logMARunits. There was no statistically significant difference in outcome between medically and surgically treated groups. Four patients developed recurrent DON, and all of them were diabetics. Conclusion: Male gender, hyperthyroid state, and smoking are risk factors for developing DON. VEP, apical crowding, and optic nerve compression are sensitive indicators for diagnosing DON. Diabetics may have a more defiant course and are prone to develop recurrent DON.

Evaluation of the effect of myopia on visual evoked potential in medical students

Background: Visual evoked potentials (VEPs) are electrical potential differences recorded from the occipital lobe in response to different visual stimulus. In myopic individuals, there is blurring of the stimuli, causing defocusing which tends to affect the VEP parameters. Aim and Objective: The study was designed and done to evaluate the effect of various degrees of myopia on VEP in medical students of age 18–24 years. Materials and Methods: A total of 120 subjects were included in this study, consist of 60 individuals without having any refractive disorders and 60 individuals having various degree of myopia, that is, 22 subjects with mild myopia of <?3D, 26 subjects with moderate myopia of ?3 to ?6D, and 12 subjects with severe myopia of > ?6D. The study was approved by Ethical and Research Committee, Govt. Medical College, Patiala. Results: In the present study, mean values for P100 latency were significantly high in myopic group as than in control group. Furthermore, mean values for N75 latency were significantly high in the myopic group as compared to the control group and mean values for N145 latency were significantly high in the myopic group as compared to the control group for both the right and left eyes. Mean values for amplitude (N75-P100) was significantly lower for the myopic group as compared to the control group for both the left and right eyes. There is prolongation of latencies in myopic individuals as compared to the control and latencies increase with the increase in degree of myopia. Furthermore, there is decrease in the amplitude in myopic individuals and it decreases with the increase in degree of myopia. Conclusion: The mean values for latencies were found to be comparable and the mean values of latencies were found to be increasing with increase of degree of myopia. Probably, the reason behind this result may be the optical blurring of the stimulus which lead to defocusing, therefore causes the prolongation of latency. The mean values for amplitude were found to be comparable and the mean values of amplitude were found to be decreasing with increase of degree of myopia. Probably, the reason for our finding is that in a pattern reversal VEP, the amplitude relies on the visual system’s ability to determine the pattern and on the degree of retinal image focus.

Alteration in pattern reversal visual evoked potential in pediatric population with amblyopia and spherical refractive errors

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.

Relationship between optical coherence tomography angiography and visual evoked potential in patients with multiple sclerosis

Purpose: This study aimed to identify an easy?to?apply biomarker by correlating visual evoked potential (VEP) with optical coherence tomography angiography (OCTA) results in multiple sclerosis (MS). Methods: Our study was planned prospectively. Patients with MS were divided into two groups, VEP prolonged group 1 and VEP normal group 2. Age?matched and gender?matched healthy individuals (group 3) were included as the control group. Vascular density (VD) of the optic nerve head (ONH) and radial peripapillary capillaries (RPCs) were measured and recorded by OCTA. The optic nerve damage of patients was measured and recorded with a VEP device. Results: Thirty?two eyes were included in group 1, 50 eyes were included in group 2, and 51 healthy eyes were included in group 3. In terms of visual acuity, group 1 was significantly lower than the other groups (P < 0.001). Regardless of the prolongation of p100 latency in patients with MS, whole image, inside disc ONH VD and in the same sectors in RPC VD were found to be significantly lower than the control group (P < 0.05). Retinal nerve fiber layer thickness was found to be significantly lower in group 1 than in group 2 and group 3 (P < 0.05). There was a significant correlation between low ONH VD and RPC VD and prolonged VEP P100 (P < 0.05). Conclusion: VEP measurements can be correlated with OCTA measurements in patients with MS and can be used as a biomarker to determine the degree of optic nerve damage

Study of visual evoked potentials in asymptomatic HIV-positive persons

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.

Therapeutic potential of human umbilical cord–derived mesenchymal stem cells transplantation in rats with optic nerve injury

Purpose: There are no effective treatments currently available for optic nerve transection injuries. Stem cell therapy represents a feasible future treatment option. This study investigated the therapeutic potential of human umbilical cord–derived mesenchymal stem cell (hUC?MSC) transplantation in rats with optic nerve injury. Methods: Sprague–Dawley (SD) rats were divided into three groups: a no?treatment control group (n = 6), balanced salt solution (BSS) treatment group (n = 6), and hUC?MSCs treatment group (n = 6). Visual functions were assessed by flash visual evoked potential (fVEP) at baseline, Week 3, and Week 6 after optic nerve crush injury. Right eyes were enucleated after 6 weeks for histology. Results: The fVEP showed shortened latency delay and increased amplitude in the hUC?MSCs treated group compared with control and BSS groups. Higher cellular density was detected in the hUC?MSC treated group compared with the BSS and control groups. Co?localized expression of STEM 121 and anti?S100B antibody was observed in areas of higher nuclear density, both in the central and peripheral regions. Conclusion: Peribulbar transplantation of hUC?MSCs demonstrated cellular integration that can potentially preserve the optic nerve function with a significant shorter latency delay in fVEP and higher nuclear density on histology, and immunohistochemical studies observed cell migration particularly to the peripheral regions of the optic nerve.

Progresses and prospects on frequency recognition methods for steady-state visual evoked potential / 生物医学工程学杂志

Steady-state visual evoked potential (SSVEP) is one of the commonly used control signals in brain-computer interface (BCI) systems. The SSVEP-based BCI has the advantages of high information transmission rate and short training time, which has become an important branch of BCI research field. In this review paper, the main progress on frequency recognition algorithm for SSVEP in past five years are summarized from three aspects, i.e., unsupervised learning algorithms, supervised learning algorithms and deep learning algorithms. Finally, some frontier topics and potential directions are explored.

Characteristics of Visual Evoked Potential in Different Parts of Visual Impairment / 法医学杂志

OBJECTIVES@#To study the quantitative and qualitative differences of visual evoked potential (VEP) in monocular visual impairment after different parts of visual pathway injury.@*METHODS@#A total of 91 subjects with monocular visual impairment caused by trauma were selected and divided into intraocular refractive media-injury group (eyeball injury group for short), optic nerve injury group, central nervous system injury and intracranial combined injury group according to the injury cause and anatomical segment. Pattern Reversal visual evoked potential (PR-VEP) P100 peak time and amplitude, Flash visual evoked potential (F-VEP) P2 peak time and amplitude were recorded respectively. SPSS 26.0 software was used to analyze the differences of quantitative (peak time and amplitude) and qualitative indexes (spatial frequency sweep-VEP acuity threshold, and abnormal waveform category and frequency) of the four groups.@*RESULTS@#Compared with healthy eyes, the PR-VEP P100 waveforms of the intraocular eyeball injury group and the F-VEP P2 waveforms of the optic nerve group showed significant differences in prolonged peak time and decreased amplitude in injured eyes (P<0.05). The PR-VEP amplitudes of healthy eyes were lower than those of injured eyes at multiple spatial frequencies in central nervous system injury group and intracranial combined injury group (P<0.05).The amplitude of PR-VEP in patients with visual impairment involving central injury was lower than that in patients with eye injury at multiple spatial frequencies. The frequency of VEP P waveforms reaching the threshold of the intraocular injury group and the optic nerve injury group were siginificantly different from the intracranial combined injury group, respectively(P<0.008 3), and the frequency of abnormal reduction of VEP amplitude of threshold were significantly different from the central nervous system injury group, respectively(P<0.008 3).@*CONCLUSIONS@#VEP can distinguish central injury from peripheral injury, eyeball injury from nerve injury in peripheral injury, but cannot distinguish simple intracranial injury from complex injury, which provides basic data and basis for further research on the location of visual impairment injury.

Diagnostic performance of isolated-check visual evoked potential versus perimetry with blue-yellow in patients with open angle glaucoma / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To evaluate the diagnostic performance of the isolated-checked visual evoked potential(IC-VEP)in the detection of open angle glaucoma and compared it to the blue-yellow perimetry(B/YP)and optical coherent tomography(OCT).<p>METHODS: In a retrospective analysis, IC-VEP, perimetry and OCT were performed on 101 subjects(<i>n</i>=35, normal; <i>n</i>=30, early glaucoma; <i>n</i>=36, moderate and advanced glaucoma)from China. The sensitivity of IC-VEP, perimetry and OCT for detection of glaucoma, as well as the agreement within these 3 methods, were calculated to evaluate their clinic performance.<p>RESULTS: In the early primary open angle glaucoma(POAG)group the sensitivity of IC-VEP, blue-yellow perimetry and OCT were 70.00%, 70.00% and 63.33%, respectively. In the moderate advanced POAG group, the sensitivity of IC-VEP, OCT and blue-yellow perimetry were 86.11%, 88.89% and 91.67%, respectively. The specificity of IC-VEP was 91.43%. The results of IC-VEP were highly consistent with OCT and blue-yellow visual field tests(kappa: 0.721-1.000, <i>P</i><0.05).<p>CONCLUSION:As an objective examination of visual function, IC-VEP can be used for early diagnosis of glaucoma. It may be a useful tool for monitoring the function of RGCs in suspected glaucoma patients.

Characteristics of visual conduction under Top-down perceptual processing / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To study the visual efficiency and characteristics of Top-down perceptual pathway in children.<p>METHODS: Totally 26 children volunteers in the outpatient department from January to June 2020 were selected. We adopted the photos of children's self-face as the Top-down perceptive fixation point pictures. The N75 time, P100 peak time, P100 amplitude and P100 repolarization time were recorded by graphic visual evoked potential(PVEP)examination.<p>RESULTS: Different visual perception pathway had no significant effect on the latency of N75, while different spatial frequencies have a significant effect on the N75 time. The latency of N75 was prolonged under high frequency spatial stimulation. The interaction between visual perceptual processing path and spatial frequency has a significant effect on the peak time of P100.Under Top-down condition, the peak time of P100 was significantly shortened under high-frequency spatial stimulus. Different visual perception paths and spatial frequencies had significant effects on P100 amplitude, and Top-down perceptual processing and spatial frequencies had significant effects on the time of P100 wave repolarization, while the interaction between processing paths and spatial frequencies had no significant effects.<p>CONCLUSION:Under Top-down visual perceptual, the visual conduction velocity and visual condition efficiency are improved in children's visual process.

Research on flash visual evoked potential and dynamic changes of Tau and its phosphorylation in rat model of traumatic optic neuropathy / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To detect the visual dysfunction, and investigate the changes of Tau and its phosphorylated Ser396/Ser404 forms in retinas and optic nerves in traumatic optic neuropathy(TON)model rats by using FVEP technique.<p>METHODS: Totally 30 SD rats were conducted FVEP electrode implantation. One week later, all rates were implemented TON operation with the optic nerve of left eye crushed and the optic nerve of right eye exposed(sham-operated). FVEP detections were performed respectively in these TON model rats at 1, 3, 7, 14, and 28d post crush, with 5 rats tested at each time point. After FVEP tests were taken, rats were sacrificed and then retinas and optic nerves of left eyes were separated for detecting the expression levels of Tau and pTau-Ser396/404 by Western Blot.<p>RESULTS: Typical FVEP waves were observed in the sham-operated eyes. Compared to the sham group, the N2 waves were significantly delayed and the amplitude of N2-P2 were greatly reduced at each time point in the operation eyes. However, the differences of N2 wave and the amplitude reduction of N2-P2 were not significant at each time point after crush. The contents of total Tau protein in retinas of TON rats sharply decreased at 1d post crush, briefly recovered at 7d post crush, and remained a slightly lower level than normal condition till 28d. The changes of pTau-Ser396/404 were consistent with the changes of total Tau in retains and the Ser396 was the main phosphorylation site. However, the total Tau contents in optic nerves of TON rats increased gradually, and peaked at the 14d post crush and remained till 28d. The changes of pTau-Ser396/404 were similar to the changes of total Tau in optic nerves, which peaked at 7d post crush. However, Ser404 was the main phosphorylation site of Tau in optic nerves.<p>CONCLUSION: The related indexes of N2 and P2 waves in FVEP can be used to detect the visual dysfunction in TON rats. After TON, the content changes of total Tau in retinas and optic nerves were much different while the changes of pTau-Ser396/404 followed the alterations of total Tau in the two locations. However, the main phosphorylation site of Tau was differnet according to the locations.

Robotic arm control system based on augmented reality brain-computer interface and computer vision / 生物医学工程学杂志

Brain-computer interface (BCI) has great potential to replace lost upper limb function. Thus, there has been great interest in the development of BCI-controlled robotic arm. However, few studies have attempted to use noninvasive electroencephalography (EEG)-based BCI to achieve high-level control of a robotic arm. In this paper, a high-level control architecture combining augmented reality (AR) BCI and computer vision was designed to control a robotic arm for performing a pick and place task. A steady-state visual evoked potential (SSVEP)-based BCI paradigm was adopted to realize the BCI system. Microsoft's HoloLens was used to build an AR environment and served as the visual stimulator for eliciting SSVEPs. The proposed AR-BCI was used to select the objects that need to be operated by the robotic arm. The computer vision was responsible for providing the location, color and shape information of the objects. According to the outputs of the AR-BCI and computer vision, the robotic arm could autonomously pick the object and place it to specific location. Online results of 11 healthy subjects showed that the average classification accuracy of the proposed system was 91.41%. These results verified the feasibility of combing AR, BCI and computer vision to control a robotic arm, and are expected to provide new ideas for innovative robotic arm control approaches.

Effect of acupuncture on pattern visual evoked potential of cerebral visual impairment in children aged 3-10 years / 中国针灸

OBJECTIVE@#To observe clinical effect of acupuncture combined with conventional visual stimulation on cerebral visual impairment (CVI) in children aged 3-10 years and influence on the pattern visual evoked potential (P-VEP).@*METHODS@#A total of 60 cases of children aged 3-10 years with CVI were randomly divided into an observation group and a control group, 30 cases in each group. The children in the control group received conventional visual stimulation therapy, 1 month as a course of treatment. On the basis of the control group, the children in the observation group was treated with acupuncture at Baihui (GV 20), Jingming (BL 1), Taiyang (EX-HN 5), Sibai (ST 2), etc. 3 times a week, and the treatment was given 4 weeks continuously as a course. Both groups received 3 courses of treatment. The visual acuity and P-VEP improvement were compared between the two groups before and after treatment.@*RESULTS@#After treatment, the incubation period (P100-L) of the two groups was shorter than before treatment, and the amplitude (P100-A) was higher than before treatment (@*CONCLUSION@#Acupuncture combined with conventional visual stimulation can improve the incubation period (P100-L) and amplitude (P100-A) of P-VEP in children with CVI, and improve the best corrected visual acuity in children, the clinical effect is better than the conventional visual stimulation alone.