Effect of sodium tungstate on visual evoked potentials in diabetic rats

AIM： To evaluate the effect of sodium tungstate on visual evoked potentials（VEPs） in diabetic rats.· METHODS： Wistar rats were randomly divided into three groups as normal control, diabetic control and diabetic rats treated with sodium tungstate. Diabetes was induced by single intraperitoneal injection of streptozotocin（50 mg/kg）. Sodium tungstate [40 mg/（kg·d）]was administered for 12 wk and then VEPs were recorded.Additionally, thiobarbituric acid reactive substance（TBARS） levels were measured in brain tissues.·RESULTS： The latencies of P1, N1, P2, N2 and P3 waves were significantly prolonged in diabetic rats compared with control group. Diabetes mellitus caused an increase in the lipid peroxidation process that was accompanied by changes in VEPs. However, prolonged latencies of VEPs for all components returned to control levels in sodium tungstate-treated group. The treatment of sodium tungstate significantly decreased brain TBARS levels and depleted the prolonged latencies of VEP components compared with diabetic control group.· CONCLUSION： Sodium tungstate shows protective effects on visual pathway in diabetic rats, and it can be worthy of further study for potential use.

Short-duration transient visual evoked potentials and color reflectivity discretization analysis in glaucoma patients and suspects

AIM： To evaluate the use of short-duration transient visual evoked potentials（VEP） and color reflectivity discretization analysis（CORDA） in glaucomatous eyes,eyes suspected of having glaucoma,and healthy eyes.METHODS： The study included 136 eyes from 136 subjects： 49 eyes with glaucoma,45 glaucoma suspect eyes,and 42 healthy eyes.Subjects underwent Humphrey visual field（VF） testing,VEP testing,as well as peripapillary retinal nerve fiber layer optical coherence tomography imaging studies with post-acquisition CORDA applied.Statistical analysis was performed using means and ranges,ANOVA,post-hoc comparisons using Turkey＇s adjustment,Fisher＇s Exact test,area under the curve,and Spearman correlation coefficients.RESULTS： Parameters from VEP and CORDA correlated significantly with VF mean deviation（MD）（P〈0.05）.In distinguishing glaucomatous eyes from controls,VEP demonstrated area under the curve（AUC） values of 0.64-0.75 for amplitude and 0.67-0.81 for latency.The CORDA HR1 parameter was highly discriminative for glaucomatous eyes vs controls（AUC=0.94）.CONCLUSION： Significant correlations are found between MD and parameters of short-duration transient VEP and CORDA,diagnostic modalities which warrant further consideration in identifying glaucoma characteristics.

Normal values of flash visual evoked potentials in rabbits: Differences between the sexes and the eyes

BACKGROUND: The wave form, latency and wave amplitude of visual evoked potentials (VEP) are obviously affected by the stimulative parameters, physiological status of the subjects and anesthetics, thus there are greater normal variations and individual differences. The features of flash VEP (F-VEP) are to be observed. OBJECTIVE: To observe and compare the differences of F-VEP latencies and wave amplitudes between eyes in rabbits, and investigate the correlation with sex and the side of eyes. DESIGN: A comparative animal experiment. SETTING: Department of Neurosurgery, General Hospital of Chinese PLA. MATERIALS: The experiment was carried out in the neurophysiological laboratory of the Institute of Neurosciences, General Hospital of Chinese PLA from September 2004 to February 2005. Thirty big-ear rabbits of clean degree, 15 males and 15 females, weighing 2.0-2.5 kg, were provided by the animal center of the General Hospital of Chinese PLA. METHODS: Viking-IV perioperative monitor and flash stimulator for special use were applied. The rabbits were anesthetized with intramuscular injection of compound ketamine. The recording electrode was placed at 3 mm anterior to exoccipital tuberosity (onion, Oz), and the reference electrode was placed at the ear edge of the same side. The stimulative frequency was 1.9 Hz, and the amplifier was 50 μV; The range of wave filter was 5 Hz for high pass and 100 Hz for low pass; The average overlapping was 200 times, and the analytical time was 250 ms. MAIN OUTCOME MEASURES: Comparison of F-VEP wave forms; F-VEP latencies and wave amplitudes. RESULTS: All the 30 rabbits were involved in the analysis of results. ① Comparison of F-VEP wave forms in rabbits: The F-VEP waves mainly manifested as positive-negative-positive (PNP). The F-VEP manifestations to light stimulations were extremely similar between left and right eyes, and the wave amplitudes of both eyes were obviously increased. ② Determinations of F-VEP latencies and wave amplitudes: There were no significant differences in the latencies and wave amplitudes of F-VEP between the two groups (P > 0.05), the latencies of P1, N1 and P2 waves of left eye were (32.59±2.01), (43.85±4.35) and (66.20±8.13) ms, respectively, and the wave amplitudes of P1, N1 and P2 waves of left eye were (16.45±10.22), (7.93±3.56) and (17.62±8.18) μV. F-VEP latencies were stable with small changes, whereas amplitudes had greater changes. CONCLUSION: ① The latency and wave amplitudes F-VEP were stable with good repetition. ② The latencies and wave amplitudes had no significant differences between males and females, as well as between left and right eyes. Further investigation should be undertaken on the animal and clinical field.

Effect of Wei’s triple nine needling therapy on flash visual evoked potentials in rats with traumatic optic neuropathy

Objective:To investigate the effect of Wei’s triple nine needling therapy on the N2-P2 wave of the flash visual evoked potential(FVEP)in rats of the of the transverse directional pulling model.Methods:Thirty-six Wistar rats were randomly grouped,nine were in normal control group without any treatment,and the remaining 27 were surgically modelled in the right eyes.Eighteen of these rats were randomly divided into a Wei’s triple nine needling therapy group and a model group of nine rats each after the TON model was made using the transverse quantitative retraction method.The other 9 rats were sham-operated,and only the optic nerve was exposed without retraction.On the next day of modelling,the Wei’s triple nine needling therapy group was treated with Wei’s triple nine needling therapy for 20 minutes/1 time/1 day for 14 days.The model group,sham-operated group and normal control group were not intervened.Wei's triple nine acupoints were represented as follows:1st link:"Jingming"(BL1)and"Chengqi"(ST1);2nd link:"Sizhukong"(SJ23)penetrating"Taiyang"(EX-HN5);and the third:"Fengchi"(GB 20)and"Taichong"(LV3).The FVEP of each group was observed on 1d,7d and 14d.The FVEP of each group was observed on 1d,7d and 14d.Results:Compared with the model group,the N2 wave latency and P2 wave latency were shortened in the Wei’s triple nine needling therapy on 1d(P<0.05,P<0.01);on 7d,their N2 wave latency was shortened(P<0.01)and the N2-P2 wave amplitude was increased compared with the model group(P<0.05);on 14d,their P2 wave latency was shortened(P<0.05)and the N2-P2 wave amplitude was increased.There was no statistical difference in N2 wave latency,P2 wave latency and N2-P2 wave amplitude in the sham-operated group on 1d,7d and 14d(P>0.05).The delayed N2 and P2 wave latencies in the model group did not improve from 1d to 14d(P>0.05)and the amplitude decreased throughout,showing a significant difference on 14d compared to 1d(P<0.05).In contrast,the N2 wave latency in Wei’s triple nine needling therapy group was not significantly different until 7d to 14d(P<0.05);its P2 wave latency,although significantly delayed from 1d to 7d(P<0.05),recovered on 14d and reached a level that was not statistically different from 1d and 7d(P>0.05).There was also no significant decrease in N2-P2 wave amplitude between 1d and 14d in Wei’s triple nine needling therapy group(P>0.05).Conclusion:In this experiment,the TON rat model was successfully established by the transverse quantitative retraction method,and the treatment of TON rats with Wei’s triple nine needling therapy reduced the P2 wave delay of the FVEP electrophysiological signal and increased the N2-P2 amplitude,which had a certain positive effect on the repair of optic nerve injury,probably related to its effect of improving the conduction function of the optic nerve and protecting the retinal ganglion cells that had not been degenerated and necrosed.

EXPERIMENTAL AND CLINICAL STUDY ON BILIRUBIN NEUROTOXICITY DETECTED BY VISUAL EVOKED POTENTIALS TO FLASH

Objective Evaluate the sensitivity and reliability of visual evoked potential to flash (F-VEP) in detecting bilirubin neurotoxicity and approach the risk parameters of bilirubin neurotoxicity in hyper-bilirubinemia newborns. Methods Based on the successful establishment of animal models for acute bilirubin encephalopathy by intraperitoneal infusion of bilirubin with a dosage of 100～200μg/g body weight to 1-week-old guinea pigs, the F-VEP was recorded in animal models and human neonates with hyperbilirubinemia, and the sensitivity and reliability of F-VEP in detecting bilirubin neurotoxicity were evaluated. Results F-VEP features and its P1 latency significantly correlated to brain adenosine triphosphate (ATP) level, neurobeha-vioral and neuropathological changes in experimental bilirubin encephalopathy; neonates with hyperbiliru-binemia showed significant F-VEP changes characterized by absence of P1 or P1 latency prolonged in 1～7-day-old newborns, especially when the jaundice was caused by immun oincompatibility and infectious diseases. Conclusion F-VEP would be a good discriminator for bilirubin neurotoxicity, and can become a promising technique in monitoring bilirubin encephalopathy.

The Single Training Sample Extraction of Visual Evoked Potentials Based on Wavelet Transform

Based on the good localization characteristic of the wavelet transform both in time and frequency domain, a de-noising method based on wavelet transform is presented, which can make the extraction of visual evoked potentials in single training sample from the EEG background noise in favor of studying the changes between the single sample response happen. The information is probably related with the different function, appearance and pathologies of the brain. At the same time this method can also be used to remove those signal’s artifacts that do not appear with EP within the same scope of time or frequency. The traditional Fourier filter can hardly attain the similar result. This method is different from other wavelet de-noising methods in which different criteria are employed in choosing wavelet coefficient. It has a biggest virtue of noting the differences among the single training sample and making use of the characteristics of high time frequency resolution to reduce the effect of interference factors to a maximum extent within the time scope that EP appear. The experiment result proves that this method is not restricted by the signal-to-noise ratio of evoked potential and electroencephalograph (EEG) and even can recognize instantaneous event under the condition of lower signal-to-noise ratio, as well as recognize the samples which evoked evident response more easily. Therefore, more evident average evoked response could be achieved by de-nosing the signals obtained through averaging out the samples that can evoke evident responses than de-nosing the average of original signals. In addition, averaging methodology can dramatically reduce the number of record samples needed, thus avoiding the effect of behavior change during the recording process. This methodology pays attention to the differences among single training sample and also accomplishes the extraction of visual evoked potentials from single trainings sample. As a result, system speed and accuracy could be improved to a great extent if this methodology is applied to brain-computer interface system based on evoked responses.

Comparison of isolated-check visual evoked potential and standard automated perimetry in early glaucoma and high-risk ocular hypertension

AIM：To compare the diagnostic performance of isolatedcheck visual evoked potential（ic VEP） and standard automated perimetry（SAP）,for evaluating the application values of ic VEP in the detection of early glaucoma.METHODS：Totally 144 subjects（288 eyes） were enrolled in this study.ic VEP testing was performed with the Neucodia visual electrophysiological diagnostic system.A 15% positive-contrast（bright） condition pattern was used in this device to differentiate between glaucoma patients and healthy control subjects.Signal-to-noise ratios（SNR） were derived based on a multivariate statistic.The eyes were judged as abnormal if the test yielded an SNR≤1.SAP testing was performed with the Humphrey Field Analyzer II.The visual fields were deemed as abnormality if the glaucoma hemifield test results outside normal limits;or the pattern standard deviation with P〈0.05;or the cluster of three or more non-edge points on the pattern deviation plot in a single hemifield with P〈0.05,one of which must have a P〈0.01.Disc photographs were graded as either glaucomatous optic neuropathy or normal by two experts who were masked to all other patient information.Moorfields regression analysis（MRA） used as a separate diagnostic classification was performed by Heidelberg retina tomograph（HRT）.RESULTS：When the disc photograph grader was used as diagnostic standard,the sensitivity for SAP and ic VEP was 32.3% and 38.5% respectively and specificity was 82.3% and 77.8% respectively.When the MRA Classifier was used as the diagnostic standard,the sensitivity for SAP and ic VEP was 48.6% and 51.4% respectively and specificity was 84.1% and 78.0% respectively.When the combined structural assessment was used as the diagnostic standard,the sensitivity for SAP and ic VEP was 59.2%and 53.1% respectively and specificity was 84.2% and 84.6% respectivlely.There was no statistical significance between the sensitivity or specificity of SAP and ic VEP,regardless of which diagnostic standard was based on.CONCLUSION：The diagnostic performance of ic VEP is not better than that of SAP in the detection of early glaucoma.

Characteristics of Pattern Visual Evoked Potential in Two Eyes with Varying Visual Acuity in One Eye and Forensic Application

In this study, we aimed to study the pattern visual evoked potentials （P-VEPs） in two eyes with varying visual acuity in one eye and to provide an objective estimation of visual acuity by comparing P-VEPs in one and two eyes. Thirty subjects were chosen, who had one eye with an acuity of 5.0, 4.85, 4.6, 4.0, or scieropia and obstructed vision and the other eye with an acuity of 5.0, respectively. P-VEPs were detected under the large grating stimuli at 3x4 spatial frequency, moderate grating stimuli （12× 16 spatial frequency） and small grating stimuli （48×64 spatial frequency）. Under large grating stimuli, there was no significant difference in P100 peak latency between the groups, nor was there a significant difference between the amplitude of two eyes and the amplitude of one normal-vision eye. Under moderate and small grating stimuli, there was a significant difference in P100 peak latency between the group with both eyes having an acuity of 5.0 and the group with visual acuity below 4.0 in one eye. There was a significant difference in P100 amplitude between the group with visual acuity of 5.0 in both eyes and the group with one normal-vision eye. There was no significant difference in the amplitude of two eyes and the amplitude of one normal-vision eye between any other two groups. In forensic identification, characteristics and variability of P-VEPs in one and two eyes can be used to identify malingering or decline in visual acuity.

Applications of the isolated-check visual evoked potential in primary open angle glaucoma with or without high myopia

AIM:To explore the diagnostic performance of isolatedcheck visual evoked potential(ic VEP)for primary open angle glaucoma(POAG)in both highly myopic and nonhighly myopic populations and compare it with those of optical coherence tomography(OCT)and Heidelberg retinal tomography(HRT)parameters.METHODS:A total of 126 participants were recruited,including 31 highly myopic participants with POAG(HM-POAG),36 non-highly myopic participants with POAG(NHM-POAG),25 highly myopic participants without POAG(HM)and 34 controls without high myopia(Normal).All the participants underwent a complete ophthalmic examination.The signal-to-noise ratio(SNR)was used to assess the ic VEP.Both qualitative and quantitative diagnostic performances of OCT,HRT and the ic VEP were analyzed and compared.RESULTS:Based on the criterion of SNR≤1,the diagnostic performance of the ic VEP in highly myopic subjects[area under the receiver operating characteristic curve(AUC)=0.862]was better than that in non-highly myopic subjects(AUC=0.789),and the SNR had fairly good specificity.In distinguishing the HM-POAG and HM groups,the AUC of the SNR was not different from those of the OCT and HRT parameters(P>0.05)in either the qualitative or quantitative comparison.In the qualitative analysis,the ic VEP showed good consistency with damage to the central 10°of the visual field(kappa=0.695-0.747,P<0.001).CONCLUSION:The ic VEP has the potential to discriminate individuals with and without POAG,especially in populations with high myopia.

Efficacy of nerve growth factor on the treatment of optic nerve contusion Evaluation with visual evoked potential

BACKGROUND： Pattern- visual evoked potential （PVEP） can reflect the functional status of retinal ganglial cells （RGC） and visual cortex, and is an objective examination for visual pathway function. It is a unique method for objectively examining the optic nerve function of optic ganglion cells. OBJECTIVE： To observe the effects of nerve growth factor （NGF） on PVEF in the treatment of optic nerve contusion, evaluate the clinical efficacy of NGF, and make an efficacy comparison with vitamin B12. DESIGN： A randomly grouping, controlled observation. SETTING： Department of Ophthalmology, Tangshan Gongren Hospital Affiliated to Hebei Medical University. PARTICIPANTS： Forty patients with optic nerve contusion caused by eye trauma, who received the treatment in the Tangshan Worker Hospital Affiliated to Hebei Medical University between January 2006 and June 2007, were recruited in this study. The involved 40 patients, including 34 males and 6 females, were aged 14-59 years. They were confirmed to have optic nerve contusion by ophthalmologic consultation combined with history of disease and orbital CT examination. Informed consents of treatments and detected items were obtained from all the patients. The patients were randomly divided into 2 groups with 20 in each： NGF group and vitamin B12 group. METHODS： Conservative treatment was used in the two groups. In addition, patients in the NGF group were intramuscularly injected with NGF solution 18 μg /time, once a day. Those in the vitamin B12 group were injected by the same method with common vitamin B12 of 500 μg combined with vitamin B1 of 100 mg, once a day. MAIN OUTCOME MEASURES： PVEP examination was conducted in all the patients before, one and two weeks after treatment, and latency and amplitude at P100 were detected. RESULTS： Forty patients with optic nerve contusion participated in the final analysis. Before treatment, significant differences in the latency and amplitude at P100 were not found in patients between two groups （P 〉 0.05）. For each patient in the NGF group, the latency of PVEP at P100 was significantly shortened, and the amplitude was significantly increased one and two weeks after treatment as compared with vitamin B12 group（t =2.06-2.34, P 〈 0.05）. CONCLUSION： NGF treatment can obviously improve the visual function of patients with optic nerve contusion. The curative effect of NGF is superior to vitamin B12.

Appropriate stimulation in visual evoked potential to evaluate visual perception state of athletes

BACKGROUND： Several studies have demonstrated that visual evoked potentials can be influenced by sport events. To the best of our knowledge, there are no specific parameters for the most appropriate stimulation for evaluating the functional state of athletes. OBJECTIVE： To investigate the best stimulation in visual evoked potential to apply to functional evaluation of athletes. DESIGN, TIME AND SETTING： Ninety-five, healthy students from the Shandong Normal University took part in an observational, contrast study. PARTICIPANTS： All active participants were male. Sixty-five students majored in physical education, and had participated in exercise for the duration of （4.26 ± 3.08） years. An additional 30 students majored in other subjects. METHODS： The neural electricity tester, NDI-200, was adapted to examine and record visual evoked potential with varying probes using bipolar electrodes attached to the head of all the participants in a dark room. The visual evoked potential values were analyzed transversally. A chessboard pattern reversal method was applied with the following parameters： 2 Hz stimulation frequency, brightness of 90 cdp, 80% contrast, 1-100 Hz bandpass filters, and 10 μV sensitivity; 100 responses were averaged. MAIN OUTCOME MEASURES： latency, peak latencies, and inter-peak latencies were measured in N75, P100, N145 with varying probe stimulations. RESULTS： （1） Comparisons between the little check, middle check, and big check stimulation, demonstrated that the common tendencies in visual evoked potential indexes of the two groups of N75 latency were successively shorter and N145 were longer. P100-N145 peak latency was decreased and each inter-peak latency was longer. （2） Changes of N75, P100, and N145 with different check stimulations in the physical education student group： after compared with the middle check stimulation, N75 latency was significantly longer （P 〈 0.01）, and N75-P100 inter-peak latency （P 〈 0.05） and N75-N145 inter-peak latency were both shorter （P 〈 0.05）. N75-P100 inter-peak latency was shorter （P 〈 0.01） in the little check stimulation. When compared with the big check stimulation, N75 latency was significantly longer （P 〈 0.01） and N145 was shorter （P 〈 0.01）. Compared with the big check stimulation, N145 latency was significantly shorter （P 〈 0.05） （3） Changes of N75, P100, and N145 with different check stimulations in the normal students： when compared with the big check stimulation, N75 latency was significantly longer （P 〈 0.05） and N145 latency was shorter （P 〈 0.05）. Each inter-peak latency was shorter （P 〈 0.05） in the little check stimulation. When comparing the middle check stimulation, N75-N145 inter-peak latency was shorter （P 〈 0.05）. CONCLUSION： Large visual evoked potential differences were observed between students majoring in physical education and other subjects when medium probe stimulation was applied. These results suggest that the use of medium probe stimulation （25 mm×25 mm） should be adopted when evaluating the functional state of athletes.

Effect of infusion pressure during cataract surgery on ganglion cells measured using isolated-check visual evoked potential

AIM： To detect the relationship between infusion pressure and postoperative ganglion cells function.METHODS： This prospective observational cohort study included sixty-one eyes that underwent uncomplicated cataract surgery. Patients were divided into two groups according to infusion time（IT） recorded using surgery equipment [Group A： IT〉IT_（mean）（27 eyes）; Group B： IT

Visual acuity evaluation in children with hydrocephalus:An electrophysiological study with sweep visual evoked potential

The objective was to measure the visual acuity (VA) of children with the diagnosis of hydrocephalus with or without peritoneal-ventricular shunt (PVS). A total of 55 children were included in the study (34 Female), with an age range of 0 to 291 weeks. The VA was measured by the sweep visual evoked potential technique. Of those with a PVS, in 31 the ventricular valve was inserted before 15 days after the diagnosis whereas in 14 the ventricular valve was inserted after 15 days. The sweep VEP was performed in all children, 95 exams (94%) were abnormal and only 6 were normal. There was a statistical difference in the VA between children with a PVS inserted before 15 days of the diagnosis and children with a PVS after 15 days (p = 0.038) or those without a shunt (p = 0.031). Children with no complications of the PVS had a better VA as compared to those with shunt complications (p < 0.001). In the group of children with complications, again those who had a shunt inserted be-fore 15 days had better VA results in com- parison to those in whom the shunt was inserted after 15 days (p = 0.029). No statistical difference in the VA was found between children without the PVS and with those in which the shunt was inserted after 15 days of the di-agnosis of hydrocephalus (p = 0.699). We conclude that the delayed insertion of the PVS may compromise the visual development of these children.

Effect of visual stimulus locations on pattern-reversal visual evoked potential An epidural electrocorticogram study

To explore the effect of the location of a visual stimulus on neural responses in the primary visual cortex （V1）, a micro-electromechanical system-based microelectrode array with nine channels was implanted on the cerebral dura mater of V1 in adult cats. 2 Hz pattern reversal checkerboard stimul were used to stimulate the four visual quadrants （i.e., upper left, upper right, lower left, and lower right fields）. The results showed that there was a N75 component of the visual evoked potential around 50-80 ms after the onset of a checkerboard stimulus, and the onset of these N75 peaks varied with different stimulus locations. The checkerboard stimuli Jnduced shorter latencJes in the contralateral V1 than in the ipsilateral V1, while the checkerboard stimulus in the upper half visual field induced shorter latencies for N75. These results suggested that the pattern-reversal stimuli induced neural activities in V1 that can be recorded with multichannel microelectrodes, and more detailed temporal and spatial properties can be measured.

Visual evoked potential by implanted scalp electrode in rats

·AIM:To establish a new method to record visual evoked potential of rats and this method was applied to retinal cone degeneration (RCD) and congenital stationary night blindness (CSNB) rats to see whether it is feasible.·METHODS:After anesthesia,the rats scalp surface was exposed and two stainless screws were implanted at 4mm in front of and 8mm behind Bregma.The front one was reference electrode and the latter one was recording electrode.The ground electrode was joined to the tail.And we recorded VEP of scotopic adaptation and photopic adaptation (The stimulus intensity of light :0.011,0.035,0.11,0.35,1.1 and 3.5cd·s/m2.They were all overlapped for 100 times.There were 2-5minutes intervals between different intensities.The frequency of stimulation was 1Hz and time course was 300 milliseconds).A week later,we recorded the VEP again in the same conditions.·RESULTS:The rats who were implanted with electrodes could live longer.When they were recorded,there was no disturbance and the waveforms were very clear and steady.There was no difference between the waveforms recorded by conventional method and those by implanted electrodes while the amplitude of new method was larger than conventional.We could get the same conclusion in RCD and CSNB rats.·CONCLUSION:Since the electrodes can be kept on the scalp for a longer time,we can not only observe dynamic changes of VEP but also observe the long-duration patho-logical changes in the rats.Because the positions of recording and reference electrodes were fixed,the system error can be reduced and the repeatability of experiments increased.·

Functional near-infrared spectroscopy can detect low-frequency hemodynamic oscillations in the prefrontal cortex during steady-state visual evoked potentialinducing periodic facial expression stimuli presentation

Brain oscillations are vital to cognitive functions,while disrupted oscillatory activity is linked to various brain disorders.Although high-frequency neural oscillations(>1 Hz)have been extensively studied in cognition,the neural mechanisms underlying low-frequency hemodynamic oscillations(LFHO)<1 Hz have not yet been fully explored.One way to examine oscillatory neural dynamics is to use a facial expression(FE)paradigm to induce steady-state visual evoked potentials(SSVEPs),which has been used in electroencephalography studies of high-frequency brain oscillation activity.In this study,LFHO during SSVEP-inducing periodic flickering stimuli presentation were inspected using functional near-infrared spectroscopy(fNIRS),in which hemodynamic responses in the prefrontal cortex were recorded while participants were passively viewing dynamic FEs flickering at 0.2 Hz.The fast Fourier analysis results demonstrated that the power exhibited monochronic peaks at 0.2 Hz across all channels,indicating that the periodic events successfully elicited LFHO in the prefrontal cortex.More importantly,measurement of LFHO can effectively distinguish the brain activation difference between different cognitive conditions,with happy FE presentation showing greater LFHO power than neutral FE presentation.These results demonstrate that stimuli flashing at a given frequency can induce LFHO in the prefrontal cortex,which provides new insights into the cognitive mechanisms involved in slow oscillation.

A STUDY ON VISUAL EVOKED POTENTIAL TO SHOW THE RELATIONSHIP BETWEEN THE EYES AND THE TWELVE REGULAR CHANNELS

The visual electrophysiologic method was used to investigate the relationship between the eyes and the 12 regular channels. The values of the latent period and the amplitude of P100 wave were calculated and compared statistically. The results show that: 1) The eyes and the 12 regular channels are closely related, no matter whether the channels are classically associated with the eyes or not, while the control (non-channel)/ point has no such relationship; 2) the degrees of relationship between the eyes and the 12 regular channels vary significantly; and 3) acupuncture at the 12 regular channels induces different effects on the visual evoked potential that the Urinary Bladder Channel presents a facilitation effect whereas all the other channels chiefly show an inhibitory effect.

A Method of SSVEP Signal Identification Based on Improved eCAA

Brain-computer interfaces(BCI)based on steady-state visual evoked potentials(SSVEP)have attracted great interest because of their higher signal-to-noise ratio,less training,and faster information transfer.However,the existing signal recognition methods for SSVEP do not fully pay attention to the important role of signal phase characteristics in the recognition process.Therefore,an improved method based on extended Canonical Correlation Analysis(eCCA)is proposed.The phase parameters are added from the stimulus paradigm encoded by joint frequency phase modulation to the reference signal constructed from the training data of the subjects to achieve phase constraints on eCCA,thereby improving the recognition performance of the eCCA method for SSVEP signals,and transmit the collected signals to the robotic arm system to achieve control of the robotic arm.In order to verify the effectiveness and advantages of the proposed method,this paper evaluated the method using SSVEP signals from 35 subjects.The research shows that the proposed algorithm improves the average recognition rate of SSVEP signals to 82.76%,and the information transmission rate to 116.18 bits/min,which is superior to TRCA and traditional eCAA-based methods in terms of information transmission speed and accuracy,and has better stability.

A Secure Cryptographic System Based on Steady-State Visual Evoked Potential Brain-Computer Interface Technology

Addressing the vulnerability of contact-based keyboard password systems to disclosure,this paper proposes and validates the feasibility of a non-contact secure password system based on brain-computer interface(BCI)technology that detects steady-state visual evoked potential(SSVEP)signals.The system first lets a testee look at a digital stimulus source flashing at a specific frequency,and uses a wearable dry electrode sensor to collect the SSVEP signal.Secondly,a canonical correlation analysis method is applied to analyze the frequency of the stimulus source that the testee is looking at,and feeds back a code result through headphones.Finally,after all password codes are input,the system makes a judgment and provides visual feedback to the testee.Experiments were conducted to test the accuracy of the system,where twelve stimulus target frequencies between 10-16Hz were selected within the easily recognizable flicker frequency range of human brain,and each of them was tested for 12 times.The results demonstrate that this SSVEP-BCI-based system is feasible,achieving an average accuracy rate of 97.2%,and exhibits promising applications in various domains such as financial transactions and identity recognition.

Impacts of acupuncture on brainstem evoked potentials in patients with primary depression

Objective To observe the impacts of acupuncture on brainstem evoked potentials in the patients with primary depression. Methods Forty cases of primary depression were treated by acupuncture at Baihui （百会 GV 20）, Yinatng （印堂 GV 29）, DazhuT （大椎 GV 14）, bilateral Shenmen （神门 HT 7）, bilateral Taichong （太冲 LR 3）, bilateral Neiguan （内关 PC 6） and SanyTnjiao （三阴交 SP 6）. The needles were retained for 30 min. Acupuncture treatment was given once every two days, three treatments a week. The brainstem auditory evoked potential （BAEP） and visual evoked potential （VEP） were observed in 6 weeks of treatment. The change in Hamilton depression scale （HAMD） score was observed before and after treatment in the depression group. Results After treatment, VEP wave latency was shortened significantly in patients of depression （P〈0.05）, BAEPIII wave latency was shortened significantly （P〈0.05）. The score of HAMD was decreased apparently in the depression group （P〈0.05）. Conclusions The stressability of visual and auditory stimuli in the central nervous system was decreased in the patients of depression. Acupuncture shortens remarkably the brainstem evoked potentials latency in the patients of depression and achieves the effective results in the treatment of primary depression.