The maximum length sequence (m-sequence) has been successfully used to study the linear/nonlinear components of auditory evoked potential (AEP) with rapid stimulation. However, more study is needed to evaluate the effect of the m-sequence order in terms of the noise attenuation performance. This study aimed to address this issue using response-free electroencephalogram (EEG) and EEGs with nonlinear AEPs. We examined the noise attenuation ratios to evaluate the noise variation for the calculations of superimposed averaging and cross-correlation, respectively, which constitutes the main process in the deconvolution method using the dataset of spontaneous EEGs to simulate the cases of different orders (order 5 to 12) of m-sequences. And an experiment using m-sequences of order 7 and 9 was performed in true cases with substantial linear and nonlinear AEPs. The results demonstrate that the noise attenuation ratio is well agreed with the theoretical value derived from the properties of m-sequences on the random noise condition. The comparison of waveforms for AEP components from two m-sequences showed high similarity suggesting the insensitivity of AEP to the m-sequence order. This study provides a more comprehensive solution to the selection of m-sequences which will facilitate the feasible application on the nonlinear AEP with m-sequence method.
Steady-state flsash visual evoked potentials (SFVEPs) of 30 Hz were recorded for 46 normal subjects (89 eyes )and 35 patients (51 eyes )with optic neuropathy. The visual acuities of 58.8%affected eyes were less than 0.1. The recorded waveforms were analyzed by discrete Foruier transform (DTF). The amplitudes and phases of fundamental response component and second harmonic were abstracted as characteristic values of the waveform.The total abnormal ratio was 80. 4%. The abnormal types showed the reduced amplitudes,reduced amplitude with phase change, the phases changes, and flat wave. The advantages of SFVEPs in clinical application were discussed. （Chin J Ocul Fundus Dis,1994,10:213-215）
目的 探讨躯体感觉诱发电位（SEP）在颈脊髓损伤术前、术中监测的意义。 方法 纳入2010年1月－2012年4月治疗的241例颈脊髓损伤患者，术前按美国脊柱脊髓损伤协会（ASIA）评分并分级，确定损伤平面。术前与术中SEP监测，分析不同损伤分级以及不同损伤平面术前的波幅及潜伏期的差异，术中SEP监测以波幅下降＞50%和或潜伏期延长＞10%为预警标准。 结果 各损伤分级组术前SEP监测：A级组SEP波消失，呈一直线，而B、C、D、E级组均测出SEP波形，根据是否可测出SEP波形，可将A级与B、C、D、E及组区别。B、C、D级组之间波幅和潜伏期均无统计学意义（P＞0.05）。E级组较B、C、D级组波幅增高、潜伏期缩短，差异有统计学意义（P＜0.05）；不完全性颈脊髓损伤组内不同损伤平面组之间波幅和潜伏期差异均无统计学意义（P＞0.05）。术中SEP对脊髓功能损伤监测的灵敏度83.3%、特异度98.7%。其中术中：SEP阳性8例，真阳性5例，4例术者处理后波幅及潜伏期回复至正常范围，术后无新的神经功能损伤，另1例术者采取各种处理后波幅及潜伏期无恢复，术后神经功能损伤较术前加重；假阳性3例，1例麻醉师给予升高血压后波形恢复至正常，另2例经麻醉师调整麻醉深度后波形恢复正常，此3例术后无新的神经功能损伤。SEP阴性233例，真阴性232例，术后无新的神经功能损伤；假阴性1例，患者术中、术后波形未见异常，术后运动功能损伤程度较术前加重。 结论 ① SEP能准确评估完全性和不完性颈脊髓损伤，但对不完全性颈脊髓损伤的损伤程度不能作出准确评估、也不能区分颈脊髓损伤的损伤平面；② 术中SEP监测能较好地反映颈脊髓功能完整性，对减少颈脊髓损伤术中发生医源性颈脊髓损伤风险具有重要意义。
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.
This paper is an introduction about the resultsof SEP monitoring in 36 case from 179 cases ofperipheral nerve injuries which have been followedup at least 6 months,since the beging of 1985 tothe end of 1989 in Dapin Hospital. These cases were injured by nerve overstretching 5 cases, complicated with fracture in 14patients, sharp instrument cutting in 17 patients.Of them injured in brachial plexus 3 cases ,axil-lary nerve 1 case, median nerve combined with ul-nar nerve 3 cases, ulnar nerve 12 cases, sciatic nerve, posterior tibial nerve, common peroneal nerve and femoral nerve were 1 case. All the SEP examination results showed closely coordination with clinical entities. Therefore, SEP monitoring peripheral nerve injuries manifested very importent significance in judgement of the injured nerve function.
This paper realized a portable brain-computer interface (BCI) system tailored for smart healthcare. Through the decoding of steady-state visual evoked potential (SSVEP), this system can rapidly and accurately identify the intentions of subjects, thereby meeting the practical demands of daily medical scenarios. Firstly, an SSVEP stimulation interface and an electroencephalogram (EEG) signal acquisition software were designed, which enable the system to execute multi-target and multi-task operations while also incorporating data visualization functionality. Secondly, the EEG signals recorded from the occipital region were decomposed into eight sub-frequency bands using filter bank canonical correlation analysis (FBCCA). Subsequently, the similarity between each sub-band signal and the reference signals was computed to achieve efficient SSVEP decoding. Finally, 15 subjects were recruited to participate in the online evaluation of the system. The experimental results indicated that in real-world scenarios, the system achieved an average accuracy of 85.19% in identifying the intentions of the subjects, and an information transfer rate (ITR) of 37.52 bit/min. This system was awarded third prize in the Visual BCI Innovation Application Development competition at the 2024 World Robot Contest, validating its effectiveness. In conclusion, this study has developed a portable, multifunctional SSVEP online decoding system, providing an effective approach for human-computer interaction in smart healthcare.
Objective To investigate the characteristic of the multifocal visual evoked potentials(MVEP)and the visual function across the visual field in anisometropic amblyopes and isometropic amblyopes. Methods MVEP from 32 anisometropic amblyopic eyes and 31 control eyes were tested. Results In anisometropic amblyopic eyes,the latencies of MVEP were significantly prolonged．The amplitudes of MVEP were significantly attenuated in the central region of the visual field,and these phenomena gradually reduced with the increase of the eccentricity． Conclusion The visual function of anisometropic amblyopic eyes is reduced more significantly in the central region than in the peripheral region of the visual field. (Chin J Ocul Fundus Dis,20000,16:27-29)