帕金森病人苍白球神经元放电的自适应阈值检测

自动选取合适的阈值以适应不同信噪比的信号,达到检测神经元放电的目的。依据微电极记录的信号,采用闭环方式自动递归调整阈值,逐次检测神经元放电。对合成的模拟神经放电信号及临床手术中微电极记录的112个病人的神经元放电信号处理,检测出了不同信噪比信号中的神经元放电脉冲,这些放电脉冲反映了神经核团的电生理特征。根据检测的神经元放电,可以对不同神经核团放电特征进行客观定量的分析,准确识别手术中微电极所在的神经核团,对于指导靶点定位具有重要的意义。     

电刺激腹中隔区对兔视前区前下丘脑温敏神经元放电的影响

目的和方法:采用玻璃微电极细胞外引导单位神经元放电的方法,观察电刺激兔腹中隔区(VSA)时,视前区-下丘脑前部(POAH)温度敏感神经元放电频率的变化。结果:电刺激腹中隔区可使视前区-下丘脑前部热敏神经元放电频率增加,冷敏神经元放电频率减少。结论:腹中隔区可能通过影响视前区-下丘脑前部温敏神经元放电频率而参与体温调节。     

电刺激VSA对IL-1_β作用下兔POAH温敏神经元放电的影响

目的和方法：本实验采用微电极细胞外记录,在３２只新西兰兔下丘脑视前区（ＰＯＡＨ）记录温敏神经元单位放电,观察电刺激腹中膈区（ＶＳＡ）对致热原ＩＬ－１β作用下兔ＰＯＡＨ温敏神经元放电的影响。结果：（ｌ）侧脑室注射白介素－１β（ＩＬ－１β）能使ＰＯＡＨ热敏神经元放电减少,冷敏神经元放电增加;而侧脑室注射人工脑脊液（ＡＣＳＦ）对热敏神经元和冷敏神经元的放电均无明显影响。（２）电刺激ＶＳＡ可反转ＩＬ－１β对ＰＯＡＨ热敏神经元和冷敏神经元的上述作用。结论：ＶＳＡ可能作为负调节中枢参与致热原作用下的体温调节。     

酚妥拉明阻断去甲肾上腺素对大鼠束旁核痛反应神经元电活动的影响

目的：去甲肾上腺素及其α受体阻断剂酚妥拉明对大鼠束旁核痛反应神经元电活动的影响。方法：以串刺激右侧坐骨神经为伤害性刺激，用玻璃微电极细胞外记录大鼠束旁核痛反应神经元电活动。结果：脑室去甲肾上腺素抑制旁核束旁核痛兴奋神经元放电，促进痛抑制神经元放电，此作用可被酚妥拉明阻断。结论：酚妥拉明阻断去甲肾上腺素对大鼠束旁核痛反应神经元电活动的抑制作用，提示去甲肾上腺素的镇痛作用与α肾上腺素能受体关系密切。     

电刺激POAH对IL - 1_β 作用下兔VSA温敏神经元放电的影响(英文)

目的和方法 :为了从细胞水平进一步探讨发热时体温正、负调节中枢的调节机制 ,本实验采用微电极细胞外记录技术 ,在 2 6只新西兰兔脑腹中隔区 (ventralseptalarea ,VSA)记录了温敏神经元单位放电 ,观察电刺激下丘脑视前区 (preopticanteriorhypothalamus,POAH)对致热原IL - 1β 作用下兔VSA温敏神经元放电的影响。结果 :(1)侧脑室注射的白介素 - 1β(IL - 1β)能使VSA热敏神经元放电频率增加 ,冷敏神经元放电减少 ,而侧脑室注射等量人工脑脊液 (ACSF)对热敏神经元和冷敏神经元的放电均无明显影响。 (2 )电刺激POAH可反转致热原IL- 1β 对VSA热敏神经元和冷敏神经元的上述作用。结论 :在致热原作用下的体温调节中 ,正调节中枢POAH和负调节中枢VSA具有密切的相互作用     

电刺激VSA对IL-1β作用下兔POAH温敏神经元放电的影响关

目的和方法:本实验采用微电极细胞外记录,在32只新西兰兔下丘脑视前区(POAH)记录温敏神经元单位放电,观察电刺激腹中膈区(VSA)对致热原IL-1_β作用下兔POAH温敏神经元放电的影响。结果:(1)侧脑室注射白介素-1_β(IL-1_β)能使POAH热敏神经元放电减少,冷敏神经元放电增加;而侧脑室注射人工脑脊液(ACSF)对热敏神经元和冷敏神经元的放电均无明显影响。(2)电刺激VSA可反转IL-1_β对POAH热敏神经元和冷敏神经元的上述作用。结论:VSA可能作为负调节中枢参与致热原作用下的体温调节。     

乙酰胆碱和谷氨酸对碘缺乏大鼠海马单位放电活动的影响

目的：探讨地方性克汀病智力低下与神经元电活动及神经递质的关系。方法：采用多管玻璃微电极微电泳技术，观察乙酰胆碱和谷氨酸对碘缺乏子代大鼠海马神经元单位自发放电活动的影响。结果：泳入乙酰胆碱和谷氨酸后，对照组海马神经元单位自发放电频率均显著增多，呈兴奋性反应。而碘缺乏子代大鼠均无明显变化，且抑制性反应也较对照组多。结论：碘缺乏子代大鼠学习记忆力低下与海马结构存在胆碱能和谷氨酸能系统的功能障碍有关     

苍白球损毁术中微电极的位置识别方法

在治疗帕金森病的苍白球损毁外科手术中,微电极在苍白球中的位置只能通过分析微电极测量的细胞放电特征,依靠主观经验判定。我们以临床微电极信号为基础,利用峰峰时间间隔因子,提出了客观定量的识别微电极位置的方法。该方法能有效的识别出沿微电极针道苍白球组织的变化以及针道是否偏离,识别结果与苍白球解剖结构和手术情况相吻合,此方法可用于临床手术导向。     

大鼠中缝背核神经元细胞内HRP标记的研究

<正> 直视下将玻璃微电极插入35只大鼠中缝背核外侧亚核(LDR)内,用电生理方法寻找单个5—HT能神经元,共记录到具有慢而规律的自发放电的单个神经元30个。其自发放电的频率为1.3±0.2次/秒,记录1-2分钟后,再对该神经元行细胞内HRP标记。结果表明:具有典型的5-HT能电学特性且HRP充盈较好的LDR神经元共有7个。均为大多角型神经元,胞体直径为20—25μm,从胞体发出的初级树突有4-7支,在次级树突及终支     

电刺激POAH对IL-1β作用下兔VSA温敏神经元放电的影响

目的和方法:为了从细胞水平进一步探讨发热时体温正、负调节中枢的调节机制,本实验采用微电极细胞外记录技术,在26只新西兰兔脑腹中隔区(ventralseptalarea,VSA)记录了温敏神经元单位放电,观察电刺激下丘脑视前区(preopticanteriorhypothalamus,POAH)对致热原IL-1_β作用下兔VSA温敏神经元放电的影响。结果:(1)侧脑室注射的白介素-1_β(IL-1_β)能使VSA热敏神经元放电频率增加,冷敏神经元放电减少,而侧脑室注射等量人工脑脊液(ACSF)对热敏神经元和冷敏神经元的放电均无明显影响。(2)电刺激POAH可反转致热原IL-1_β对VSA热敏神经元和冷敏神经元的上述作用。结论:在致热原作用下的体温调节中,正调节中枢POAH和负调节中枢VSA具有密切的相互作用。     

基于人工神经网络的癫痫棘波检测方法

脑电癫痫特征波的自动提取对于患者的诊断具有重要的意义。提出一种时频分析与Jensen函数相结合的方法进行棘波检测，然后提取出棘波的波形特征，并通过人工神经网络进行进一步的判决，从而降低棘波检测的误检率。在对真实的癫痫脑电信号（EEG）的仿真实验中，该方法取得了较好的结果。     

Novel Algorithm to Suppress Random Pulse Interference in Spikes

Spikes detection and sorting play an important role in study of neural information coding. Spikes were generally obtained by threshold detection after filtered in traditional detection, which failed to suppress the random pulse interference(RPI), In this paper, a novel algorithm was provided to suppress RPI using integrated feature. The raw neural signals from the primary visual cortex in rats were detected with microelectrode array. After the feature differences between spikes and RPls were compared, the features which include waveform and non-waveform features were extracted respectively, and then the integrated feature was established based on Fisher's discrimi nant ratio to separate between spikes and RPls. The test results of simulation and experiment show that the separability capability of the integrated feature is nearly two times greater than the individual feature, the average correct recognition rate of spikes and RPls is over 93%, and the detection rate of spike is effectively improved.     

基于径向基函数神经网络的多电极阵列信号脉冲电位的分类

通过径向基函数神经网络的分析,对神经元脉冲电位信号提出了新的分类方法。对原始信号进行峰电位检测,获得脉冲电位信号样本,以主成分进行预分类,选取与类中心方差小的典型脉冲电位集合作为径向基网络的训练样本,让神经网络进行自适应学习,以实现对原始信号的分类。仿真结果表明,在对模拟的脉冲电位信号进行分类时此方法的错误率比主成分聚类法和形状聚类法小。多电极细胞外记录的海马神经元细胞电活动信号应用此方法分类也取得了较好的效果。     

Spike detection in biomedical signals using midprediction filter

Spikes such as QRS complex in ECG, epileptic seizures in EEG, fine crackles in vesicular sound and glottal closure instants in voiced sound are of diagnostic importance. Various methods of spike detection use the amplitude and frequency characteristics of the spikes. Because of the high frequency content, the spikes appear in the error signal when a linear prediction filtering scheme is used. The authors use the method of midprediction filtering for the detection of the spikes. In this method, the present sample is predicted as a weighted average of p recent past and p immediate future samples. The symmetrical nature of midprediction causes the spikes to appear in the error signal with their original basewidths. This can help in improving the reliability of spike detection, as both the amplitude and the duration of the spike can be considered as decision making parameters. It is observed that the high frequency gain of the midprediction filter is higher compared to the high frequency gain of the LPC or endprediction filter. As a result, this method works better than linear prediction for the detection of spikes.     

A study on fuzzy C-means clustering-based systems in automatic spike detection

In this study, different systems based on the fuzzy C-means (FCM) clustering algorithm are utilized for the detection of epileptic spikes in electroencephalogram (EEG) records. The systems are constructed as either single or two-stages. In contrast to single-stage systems, the two-stage system comprises a pre-classifier stage realized by a neural network. The FCM based two-stage system is also compared to a similar system implemented using the K-means clustering algorithm. The results imply that an FCM based two-stage system should be preferred as the spike detection system.     

Excess synchrony in motor cortical neurons provides redundant direction information with that from coarse temporal measures

Previous studies have shown that measures of fine temporal correlation, such as synchronous spikes, across responses of motor cortical neurons carries more directional information than that predicted from statistically independent neurons. It is also known, however, that the coarse temporal measures of responses, such as spike count, are not independent. We therefore examined whether the information carried by coincident firing was related to that of coarsely defined spike counts and their correlation. Synchronous spikes were counted in the responses from 94 pairs of simultaneously recorded neurons in primary motor cortex (MI) while monkeys performed arm movement tasks. Direct measurement of the movement-related information indicated that the coincident spikes (1- to 5-ms precision) carry approximately 10% of the information carried by a code of the two spike counts. Inclusion of the numbers of synchronous spikes did not add information to that available from the spike counts and their coarse temporal correlation. To assess the significance of the numbers of coincident spikes, we extended the stochastic spike count matched (SCM) model to include correlations between spike counts of the individual neural responses and slow temporal dependencies within neural responses (approximately 30 Hz bandwidth). The extended SCM model underestimated the numbers of synchronous spikes. Therefore as with previous studies, we found that there were more synchronous spikes in the neural data than could be accounted for by this stochastic model. However, the SCM model accounts for most (R(2) = 0.93 +/- 0.05, mean +/- SE) of the differences in the observed number of synchronous spikes to different directions of arm movement, indicating that synchronous spiking is directly related to spike counts and their broad correlation. Further, this model supports the information theoretic analysis that the synchronous spikes do not provide directional information beyond that available from the firing rates of the same pool of directionally tuned MI neurons. These results show that detection of precisely timed spike patterns above chance levels does not imply that those spike patterns carry information unavailable from coarser population codes but leaves open the possibility that excess synchrony carries other forms of information or serves other roles in cortical information processing not studied here.     

脑电信号数据压缩及棘波识别的小波神经网络方法

对小波神经网络及其算法研究的基础上,提出了一种对脑电信号压缩表达和痫样脑电棘波识别的新方法。实验结果显示,小波网络在大量压缩数据的同时,能够较好的恢复原有信号。另外,在脑电信号的时频谱等高线图上,得到了易于自动识别的棘波和棘慢复合波特征说明此方法在电生理信号处理和时频分析方面有着光明的应用前景。     

DFAspike: a new computational proposition for efficient recognition of epileptic spike in EEG

An automated method has been presented for the detection of epileptic spikes in the electroencephalogram (EEG) using a deterministic finite automata (DFA) and has been named as DFAspike. EEG data (sampled, 256 Hz) files are the inputs to the DFAspike. The DFAspike was tested with different data files containing epileptic spikes. The obtained recognition rate of epileptic spike was 99.13% on an average. This system does not require any kind of prior training or human intrusion. The result shows that the designed system can be very effectively used for the detection of spikes present in the recorded EEG signals.     

Encoding of visual information by LGN bursts.

Encoding of visual information by LGN bursts. Thalamic relay cells respond to visual stimuli either in burst mode, as a result of activation of a low-threshold Ca2+ conductance, or in tonic mode, when this conductance is inactive. We investigated the role of these two response modes for the encoding of the time course of dynamic visual stimuli, based on extracellular recordings of 35 relay cells from the lateral geniculate nucleus of anesthetized cats. We presented a spatially optimized visual stimulus whose contrast fluctuated randomly in time with frequencies of up to 32 Hz. We estimated the visual information in the neural responses using a linear stimulus reconstruction method. Both burst and tonic spikes carried information about stimulus contrast, exceeding one bit per action potential for the highest variance stimuli. The "meaning" of an action potential, i.e., the optimal estimate of the stimulus at times preceding a spike, was similar for burst and tonic spikes. In within-trial comparisons, tonic spikes carried about twice as much information per action potential as bursts, but bursts as unitary events encoded about three times more information per event than tonic spikes. The coding efficiency of a neuron for a particular stimulus is defined as the fraction of the neural coding capacity that carries stimulus information. Based on a lower bound estimate of coding efficiency, bursts had approximately 1.5-fold higher efficiency than tonic spikes, or 3-fold if bursts were considered unitary events. Our main conclusion is that both bursts and tonic spikes encode stimulus information efficiently, which rules out the hypothesis that bursts are nonvisual responses.