We have utilized the binocular flat and stereoscopic pattern to record visual evoked potentials (VEP) in normal and strabismic subjects. The aim was to find an electrophysiological correlation with the degree of binocular interaction in these subjects.The perception as tridimensional or flat derived from the disparity obtained with polaroid filters placed in front of the eyes. In normal subjects, the results demonstrated a significant increase of VEP amplitude during tridimensional perception of the pattern. In strabismic subjects the electrophysiological response were not correlated with the binocular conditions. The findings in the present study suggest that the binocular disparity in VEP examination is a useful technique and a better objective index for evaluating stereoscopic function than the psychophysical technique. （Chin J Ocul Fundus Dis,1992,8:10-13）
Brain-computer interface (BCI) has high application value in the field of healthcare. However, in practical clinical applications, convenience and system performance should be considered in the use of BCI. Wearable BCIs are generally with high convenience, but their performance in real-life scenario needs to be evaluated. This study proposed a wearable steady-state visual evoked potential (SSVEP)-based BCI system equipped with a small-sized electroencephalogram (EEG) collector and a high-performance training-free decoding algorithm. Ten healthy subjects participated in the test of BCI system under simplified experimental preparation. The results showed that the average classification accuracy of this BCI was 94.10% for 40 targets, and there was no significant difference compared to the dataset collected under the laboratory condition. The system achieved a maximum information transfer rate (ITR) of 115.25 bit/min with 8-channel signal and 98.49 bit/min with 4-channel signal, indicating that the 4-channel solution can be used as an option for the few-channel BCI. Overall, this wearable SSVEP-BCI can achieve good performance in real-life scenario, which helps to promote BCI technology in clinical practice.
Motor imaging therapy is of great significance to the rehabilitation of patients with stroke or motor dysfunction, but there are few studies on lower limb motor imagination. When electrical stimulation is applied to the posterior tibial nerve of the ankle, the steady-state somatosensory evoked potentials (SSSEP) can be induced at the electrical stimulation frequency. In order to better realize the classification of lower extremity motor imagination, improve the classification effect, and enrich the instruction set of lower extremity motor imagination, this paper designs two experimental paradigms: Motor imaging (MI) paradigm and Hybrid paradigm. The Hybrid paradigm contains electrical stimulation assistance. Ten healthy college students were recruited to complete the unilateral movement imagination task of left and right foot in two paradigms. Through time-frequency analysis and classification accuracy analysis, it is found that compared with MI paradigm, Hybrid paradigm could get obvious SSSEP and ERD features. The average classification accuracy of subjects in the Hybrid paradigm was 78.61%, which was obviously higher than the MI paradigm. It proves that electrical stimulation has a positive role in promoting the classification training of lower limb motor imagination.
Objective To investigate the relationship between graded spinal cord ischemia/reperfusion injury and somatosensory evoked potentials(SEP),neurologic function score（NFS）and the histopathological changes of spinal cord. Methods Forty rabbits were randomized and equally divided into 4 groups: shamoperation group, ischemia for 30min, 45min and 60min groups. The spinal cord ischemiareperfusion injury model was created by occlusion of the abdominal aorta in rabbits. SEP was monitored before ischemia,5,10minutes after ischemia, 15, 30 minutes, 1,2, 24 and 48 hours after reperfusion. NFS was evaluated at 6,12,24 and 48 hours after reperfusion.The pathological changes of spinal cord were observed after reperfusion 48 hours. Results The pathological characters with mild,moderate and severe spinal cord ischemia/reperfusion injury could be simulated by declamping after 30， 45 and 60 minutes infrarenal aorta crossclamping. SEP amplitude returned to normal after reperfusion 15 minutes（Pgt;0.05）and SEP latency returned to normal after reperfusion 30 minutes（Pgt;0.05）during mild spinal cord ischemia/reperfusion injury.SEP amplitude returned to normal after reperfusion 30 minutes（Pgt;0.05）and SEP latency returned to normal after reperfusion 60 minutes（Pgt;0.05）during moderate spinal cord ischemia/reperfusion injury. SEP latency increased and SEP amplitude decreased during severe spinal cord ischemia/reperfusion injury,compared with other groups, there were significant differences in SEP latency and SEP amplitude by clamping the infrarenal aorta for 60min（Plt;0.01）. With graded spinal cord ischemia/reperfusion injury, compared with shamoperation group, spinal cord ischemiareperfusion groups had significant differences in NFS（Plt;0.01）. Conclusion SEP is much quicker in the recovery of amplitude than latency during spinal cord ischemia/reperfusion. SEP is a sensitive and accurate index for spinal cord function during ischemia/reperfusion injury. SEP monitoring spinal cord ischemia/reperfusion injury during operation provides experimental basis for clinical application.
ObjectiveTo study the relationship between brain white matter fiber occult lesions and P100 wave latency of visual evoked potential (VEP) in neuromyelitis optica (NMO) patients by diffusion tensor imaging (DTI). MethodsTwenty patients with NMO who were treated between July 2008 and April 2009 were selected as the trial group. According to the VEP test, the latency of P100 wave was prolonged, the NMO patients were divided into VEP abnormal group (trial group 1) and VEP normal group (trial group 2). Twenty healthy adult volunteers served as the control group. The DTI examination in brain was done to measure the fractional anisotropy (FA) value of optic nerve (FAn), optic tract (FAt), and optic radiation (FAr);and the mean diffusivity (MD) value of optic nerve (MDn), optic tract (MDt), and optic radiation (MDr). The FA, MD, and P100 wave latency were compared between groups, and the correlation between MD, FA, and P100 wave latency of NMO were analyzed. ResultsIn the 20 NMO patients, 13 patients with VEP had prolonged bilateral P100 wave latency prolongation or no wave (trial group 1), and 7 patients had normal bilateral P100 wave latency (trial group 2). Compared with the trial group 2 and the control group, the FA values were significantly decreased, and the MD values were significantly increased in the trial group 1 (P<0.05). There was no significant difference in the FA and MD values between the trial group 2 and the control group (P>0.05). All FA (FAn, FAt, and FAr) values of each part of NMO patients were negatively correlated with the latency of P100 wave (P<0.05), all MD (MDn, MDt, and MDr) values were positively correlated with the latency of P100 wave (P<0.05). ConclusionDTI could show small pathylogical changes in the white matter fibers of visual pathway, and there is a correlation between DTI and VEP in NMO, suggesting that a more comprehensive assessment to the condition and prognosis can be made through the VEP in the clinical indicators.
Attention can concentrate our mental resources on processing certain interesting objects, which is an important mental behavior and cognitive process. Recognizing attentional states have great significance in improving human’s performance and reducing errors. However, it still lacks a direct and standardized way to monitor a person’s attentional states. Based on the fact that visual attention can modulate the steady-state visual evoked potential (SSVEP), we designed a go/no-go experimental paradigm with 10 Hz steady state visual stimulation in background to investigate the separability of SSVEP features modulated by different visual attentional states. The experiment recorded the EEG signals of 15 postgraduate volunteers under high and low visual attentional states. High and low visual attentional states are determined by behavioral responses. We analyzed the differences of SSVEP signals between the high and low attentional levels, and applied classification algorithms to recognize such differences. Results showed that the discriminant canonical pattern matching (DCPM) algorithm performed better compared with the linear discrimination analysis (LDA) algorithm and the canonical correlation analysis (CCA) algorithm, which achieved up to 76% in accuracy. Our results show that the SSVEP features modulated by different visual attentional states are separable, which provides a new way to monitor visual attentional states.
Objective To study the regulations of visual evoked potential(VEP) changes in 30 patients with multiple sclerosis (MS). Methods VEP were performed in 30 MS patients,and the results were compared with normal subjects. Results The abnormality rate of VEP were 76.7%. 82.6% of patients with abnormal VEP showed clinical visual symptoms; 17.4% among those patients have no clinical visual symptoms. Conclusion The rate of VEP abnormal in MS patients is more high. It may help more in the diagnosis of MS.
Visual evoked potential (VEP) is a commonly used technique in neurology and ophthalmology in the process of disease diagnosis and treatment, which refers to the electrical signal transmitted by the visual pathway and recorded in the skull or cortex after stimulating the retina. The effect of monitoring and protection of vision in surgery near the visual pathway has attracted more and more attention recently. This article summarizes the experience and problems of intraoperative monitoring of VEP in terms of anesthesiology and instrument development, monitoring technology, and application innovation, and proposes future research directions. The purpose is to provide a reference for clinical application and research of intraoperative VEP monitoring.
ObjectiveTo study whether the pattern visual evoked potential (P-VEP) under different spatial frequency in patients with multiple sclerosis (MS) is different from normal people. MethodsP-VEP examination under high (15') and low (60') spatial frequency was performed on 18 MS patients (36 eyes) treated in our department from September 2011 to April 2012 and 20 normal volunteers (40 eyes). Then, we analyzed the difference between the two groups under the above-mentioned two kinds of spatial frequency. ResultsThe latency of P100 of P-VEP under high spatial frequency in MS patients was (120.50±13.04) ms which was significantly different from (109.21±5.38) ms of normal volunteers (P < 0.05). The latency of P100 of P-VEP under low spatial frequency in MS patients was (109.57±12.87) ms, which was also significantly different from (103.31±5.45) ms of normal volunteers (P < 0.05). The amplitude of P100 of P-VEP under high spatial frequency in MS patients was (9.17±5.69)μV and it was significantly lower than that[(15.69±8.45)μv] of normal volunteers (P < 0.05). The amplitude of P100 of P-VEP under low spatial frequency in MS patients was (11.93±16.75)μV and it was not significantly different from normal volunteers[(13.47±9.24μV)]. Based on different corrected vision, the MS patients were divided into two groups (vision≥1.0 and vision < 1.0). For patients with vision≥1.0, the latency of P100 and the amplitude of P100 of P-VEP under high spatial frequency was (113.43±8.28) ms and (12.94±5.46)μV; the latency of P100 and the amplitude of P100 of P-VEP under low spatial frequency was (111.13±11.50) ms and (11.57±5.60)μV. For patients with vision < 1.0, the latency of P100 and the amplitude of P100 of P-VEP under high spatial frequency was (126.69±13.49) ms and (5.87±3.43)μV; the latency of P100 and the amplitude of P100 of P-VEP under low spatial frequency was (108.26±14.11) ms and (12.24±5.82)μV. There was no significant difference in the latency and amplitude of P100 under low spatial frequency between the two groups with different corrected vision (P > 0.05), but the latency and amplitude of P100 under high spatial frequency were both significantly different between those two groups (P < 0.05). ConclusionsCompared with normal people, MS patients feature latency delay and amplitude reduction of the P-VEP, which was more severe under high spatial frequency. P-VEP under high spatial frequency may become an important evidence to evaluate visual function of MS patients.
Injury of dorsal root ganglia (DRG) may cause sensory and motor dysfunction. In order to investigate the changes of somato-sensory evoked potential (SEP) and histological characteristics of DRG in different causes and different periods of injury, fifty-two rabbits were chosed to build the models. The rabbits were divided into 4 groups: Control group (n = 4); mechanical compressing group (n = 16); inflammatory injury group (n = 16); and treatment group (2% lidocaine with hydroprednisone was administered locally, n = 16). After one to eight weeks, SEP was determined and samples of DRG were obtained to observe the histological and ultrastructural changes every week. The result showed that the gap junction of microvascular endothelium in DRG had been destroyed by the mechanical compression was the major cause of the vessel permeability increasing. The increasing of endothelial pinocytic vesicles transportation and widening of endothelial gap junction were the main causes of inflammatory irritation of DRG. The local infiltration with 2% lidocaine and hydroprednisone could obviously ameliorate inflammatory injury in DRG.