闭环植入式神经刺激器的现状与发展趋势

闭环植入式神经刺激器能根据患者生理信号的变化自适应地调整刺激参数的特性,使其成为研究的热点,患者的临床需求推动其设计开发的进展。介绍3种闭环植入式神经刺激器的作用机制和刺激参数评估的理论研究以及临床应用现状,这3种闭环植入式神经刺激器分别为代表中枢神经、外周神经及脊髓神经的脑刺激器,迷走神经刺激器以及脊髓神经刺激器。概括分析闭环植入式神经刺激器研究应用中未解决的问题和发展趋势,即闭环植入式神经刺激器的作用机制仍需要深入研究,刺激参数评估的有效性需要进一步提高,应用于临床的系统有待继续完善。     

ZEP系列诱发电位／肌电图仪体感刺激器

作者介绍了ＺＥＰ系列诱发电位／肌电图仪体感刺激器的工作原理。该刺激器精确地实现了计算机对刺激频率、脉宽和强度的数字化控制，并对消除刺激器的交流干扰、实现安全隔离提供了很好的解决方法。     

ZEP系列诱发电位／肌慢图仪体感刺激器

作者介绍了ＸＥＰ系列诱发电位／肌电图仪体感刺激器的工作原理。该刺激器精确地实现了计算机对刺激频率、脉宽和强度的数字化控制，并对消除刺激器的交流干扰、实现安全隔离提供了很好的解决方法。     

自制用于麻醉药品实验的电脉冲刺激器

自制用于麻醉药品实验的电脉冲刺激器江苏省人民医院高敬文，殷雷我院麻醉科为了研究麻醉药物对气道平滑肌张力的影响，需要一台电脉冲刺激器，输出电脉冲，刺激肌肉组织收缩。脉冲刺激器输出要求：频率１０～７０Ｈｚ，脉宽０．３～３ｍｓ，输出峰－峰值１０～６０Ｖ，且...     

盆神经刺激器的研制

本文介绍了一种部分植入式盆神经刺激器，它主要由体外脉冲发射装置与体内感应接收器和刺激电极组成。文中描述该刺激器的电路设计原理及动物实验结果。     

用于磁刺激的圆形线圈的优化研究

以华科公司研发产品HKYJ-1型磁场刺激器为基础,建立磁刺激线圈的RLC模型,根据线圈峰值磁能指标对HKYJ-1型磁场刺激器磁头线圈的优化性进行讨论和评估.仿真结果证明HKYJ-1型磁场刺激器的磁刺激用圆形线圈所产生的峰值磁能与磁刺激治疗所需阈值磁能未能形成最优,线圈峰值磁能过大,其后果使线圈能耗过大,至使磁头发热过大,(与设备实际使用情况相符)最终导致刺激器工作有效性降低.根据研究结果本文提出了HKYJ-1型磁场刺激器的改进建议,提出了优化磁刺激用圆形线圈制作参数和结构参数的途径和方法,这样有效地提高华科HKYJ-1型磁场刺激器的医疗效率.     

用于动物实验的植入式神经刺激器

很多科学研究和临床应用的植入式刺激器,如心脏起搏器、骨骼肌肉刺激器等近年来得到了很大的发展。在神经科学研究中,对象通常为小型实验室动物,故对植入式刺激器的设计有特殊的要求。用于实验的植入式神经刺激器的设计要求刺激源在最大程度上满足植入式装置的需要,如尺寸小、可靠性高、安全和易于使用。笔者考虑了上述基本问题并提出了两种类型的刺激装置。由于电刺激仅能通过小电极和     

脉冲电刺激对植物生长的影响研究

本文通过分析植物电刺激的现状及存在的问题，采用脉冲电刺激植物的方法，消除了直流电刺激引起的电极极化现象。脉刺激器经电阻给每一电极提供刺激电流对植物进行刺激。实验结果表明：脉冲电刺激能够促进植物生长。     

电子耳蜗在医学中的应用

一、电刺激的种类 电刺激可分为三类:①功能性电刺激:指借电刺激恢复人体的某些收缩功能,如心脏起搏器,步态矫正器,瘫痪肢体刺激器等。1997年美国FDA批准了一种叫“自由臂”的手臂刺激器,将刺激电极植入瘫痪的手臂中,利用异侧肩部传感器控制臂和手指运动。又如美国研制一种“VOCARE”刺激器,将电极植入在骶骨下的神经节,可使脊柱损伤后大、小便失禁患者     

用于外周神经的干涉电流刺激器设计

设计了一种用于外周神经电刺激的干涉电流刺激器。该刺激器为两路电流输出,可以产生4种波形,每种波形的频率、幅度等参数可在上位机进行设置,频率分辨率为0.2 Hz,幅度分辨率为0.01 mA,时间分辨率为0.1 μs。该刺激器的特点在于可在刺激强度一定的条件下连续改变电流比,或在电流比一定的情况下连续改变刺激强度。上位机采用LabVIEW开发,下位机采用FPGA对3片DAC进行控制,DAC产生的波形信号经过隔离恒流源电路后施加到负载。经过测试,刺激器能够准确产生4种波形,电流偏差在2.6%以内,恒流效果良好。该刺激器体积小,操作简单,产生波形稳定,可以用于无损选择电刺激研究。     

Influence of a low-frequency tone on the sensitivity of primary auditory neurons: Two fiber populations

Summary The influence of a biasing low-frequency tone on the sensitivity of primary auditory nerve fibers to tone bursts at the characteristic frequency is determined. In 7% of the investigated fibers the sensitivity varied systematically with the position of the tone burst within the low-frequency tone period. In the remaining 93% of fibers this dependence was not observed.A comparison of the ratio of these numbers with the ratio of fibers from inner and outer hair cells leads to the suggestion that different responses stem from fibers innervating different types of hair cells.     

Comparison of sensory gating to mismatch negativity and self-reported perceptual phenomena in healthy adults

To better understand the possible functional significance of electrophysiological sensory gating measures, response suppression of midlatency auditory event related potential (ERP) components was compared to the mismatch negativity (MMN) and to self-rated indices of stimulus filtering and passive attention-switching phenomena in an age-restricted sample of healthy adults. P1 sensory gating, measured during a paired-click paradigm, was correlated with MMN amplitude, measured during an acoustic oddball paradigm (intensity deviation). Also, individuals that exhibited less robust P1 suppression endorsed higher rates of "perceptual modulation" difficulties, whereas component N1 suppression was more closely related to "over-inclusion" of irrelevant sounds into the focus of attention. These findings suggest that the ERP components investigated are not redundant, but correspond to distinct-possibly related-pre-attentive processing systems.     

Effects of sound intensity on a midlatency evoked response to repeated auditory stimuli in schizophrenic and normal subjects

Inhibitory gating of response to repeated stimuli is demonstrated by several event-related potentials, including the auditory P50 wave. The present study examined the effects of variation in sound intensity on this phenomenon in schizophrenics and normal subjects. Paired clicks, 500 ms apart, were presented 50 dB above threshold to 10 normal subjects and 10 schizophrenics. The normal subjects demonstrated significantly more decrement of response to the second stimulus than did the schizophrenics. When the sounds were noticeably louder(70 dB above threshold), no such difference was observed. Rather, both groups had similarly diminished gating of response. A significant difference between schizophrenics and normal subjects was also observed when the sounds were 30 dB above threshold, but the difference was smaller than that at 50 dB. At any stimulus intensity, concomitant eye movements led to loss of gating of P50 in the normal subjects.     

Early APV chronic blocked alters experience-dependent plasticity of auditory spatial representation in rat auditory cortical neurons

Development of auditory function can be affected by environment and experience. In this study, we investigated whether the NMDA receptor mediates the plasticity of auditory spatial representation during development of the rat auditory cortex. We found that early auditory experience significantly increased the auditory spatial sensitivity of A1 neurons and induced training-dependent plasticity. Implantation of Elvax-APV in the auditory cortex gradually reduced the auditory spatial sensitivity of A1 neurons and blocked the auditory spatial plasticity induced by early auditory experience. These results indicate that the NMDA receptor has a key role in experience-dependent plasticity of auditory cortical circuits immediately after birth.     

Distortions of auditory space during rapid head turns

Auditory localisation was examined using brief broadband sounds presented during rapid head turns to visual targets in the peripheral field. Presenting sounds during a rapid head movement will “smear” the acoustic cues to the sound’s location. During the early stages of a head turn, sound localisation accuracy was comparable to a no-turn control condition. However, significant localisation errors occurred when the probe sound was presented during the later part of a head turn. After correcting for head position, the estimate of lateral angle (horizontal position) in the front hemisphere was generally accurate. However, lateral angle estimates for positions in the rear hemisphere exhibited systematic errors that were especially large around the midline. Polar angle (elevation) perception remained robust, being comparable to no-turn controls whether tested early or late in the head turn. The results are interpreted in terms of a ‘multiple look’ strategy for calculating sound location, and the allocation of attention to the hemisphere containing the head-turn target.     

Stimulus duration influences the dipole location shift within the auditory evoked field component N100m

The equivalent source of the neuromagnetic auditory evoked field (AEF) component N100m shifts systematically within its latency range. In the current study, possible effects of stimulus duration on this shift were analysed. 15 subjects were stimulated monaurally with tones of different duration (50, 100, 200 ms) and AEFs were recorded successively over both hemispheres. Dipoles were calculated in 5-ms-steps from 15 ms before to 15 ms after the N100m peak maximum. A dipole location shift within the N100m latency from posterior to anterior and from superior to inferior was observed. The shift in anterior-posterior direction was found to be larger in the right compared to the left hemisphere. Stimulus duration significantly affected the degree of dipole shift in this direction. It was found to be shorter the shorter the stimulus.     

Noise-induced tinnitus: auditory evoked potential in symptomatic and asymptomatic patients

OBJECTIVES:

We evaluated the central auditory pathways in workers with noise-induced tinnitus with normal hearing thresholds, compared the auditory brainstem response results in groups with and without tinnitus and correlated the tinnitus location to the auditory brainstem response findings in individuals with a history of occupational noise exposure.

METHOD:

Sixty individuals participated in the study and the following procedures were performed: anamnesis, immittance measures, pure-tone air conduction thresholds at all frequencies between 0.25–8 kHz and auditory brainstem response.

RESULTS:

The mean auditory brainstem response latencies were lower in the Control group than in the Tinnitus group, but no significant differences between the groups were observed. Qualitative analysis showed more alterations in the lower brainstem in the Tinnitus group. The strongest relationship between tinnitus location and auditory brainstem response alterations was detected in individuals with bilateral tinnitus and bilateral auditory brainstem response alterations compared with patients with unilateral alterations.

CONCLUSION:

Our findings suggest the occurrence of a possible dysfunction in the central auditory nervous system (brainstem) in individuals with noise-induced tinnitus and a normal hearing threshold.     

Auditory memory for backward masking signals in children with language impairment

This study was designed to investigate early auditory memory and its possible contribution to an auditory processing deficit shown by some children with language impairment. Ten children with language impairment and 10 age-matched controls participated in a series of simultaneous and backward masking tasks. The same backward masking stimulus was then used to elicit a mismatch negativity response. In the behavioral conditions, children in the language impairment group had significantly higher (poorer) signal thresholds than their nonimpaired controls in backward masking, but their thresholds in simultaneous masking were not significantly different. In the mismatch-negativity conditions, latency was prolonged and the amplitude was diminished in the children with language impairment. Taken together, these psychoacoustic and electrophysiological data suggest that in a group of children with language impairment, underlying the nonsensory language disorder, there is a neurophysiological impairment in auditory memory for complex, nonlinguistic sounds.     

精神运动性癫痫患者脑诱发电位初步观察

目的研究脑诱发电位在精神运动性癫痫病人的应用。方法应用诱发电位仪对１６例精神运动性癫痫的听觉诱发电位（ＡＥＰ）、视觉诱发电位（ＶＥＰ）和听觉事件相关电位（听觉Ｐ３００）作了检测，并与正常对照组进行了比较。结果患者组波形变异大，潜伏期ＡＥＰ的Ｐ２、Ｐ３，ＶＥＰ的Ｎ１、Ｐ２以及Ｐ３００靶刺激的Ｐ２、Ｎ２均延迟，非靶刺激的Ｎ１前移。波幅ＡＥＰ的Ｐ２、ＶＥＰ的Ｐ２、Ｐ３降低，与正常对照组有显著性差异。结论ＢＥＰ技术可作为脑电图检查的一种补充手段，以便临床参考诊断此类病征。     

Sensitivity of human auditory evoked potentials to the harmonicity of complex tones: evidence for dissociated cortical processes of spectral and periodicity analysis

A strong subjective tendency exists for simultaneous sound frequencies forming an harmonic series (integer multiples of the fundamental) to "group" together into a unified auditory percept whose pitch is similar to that of the fundamental. The aim of the study was to determine whether cortical auditory evoked potentials (AEPs) to complex tones differ according to whether the component frequencies of the stimuli are harmonically related or not. AEPs were recorded to continuous complex tones comprising four or more sinusoids. The vertex-maximal "change-potentials" (CP1, CN1, CP2), recorded to a stimulus cycle comprising one harmonic and five inharmonic complexes changing every second, showed no sensitivity to harmonicity, although an additional mismatch negativity was possibly present to the harmonic complex. In a second study the CP2 was significantly attenuated when an harmonic complex changed to a new one in the presence of an unchanging sinusoidal background tone, harmonically related to the first complex but not to the second, and thus becoming perceptually distinct. This, however, might be caused by lateral inhibitory effects not related to harmonicity. In a third experiment, when four concurrent sinusoidal tones came to rest on steady frequencies after a 5-s period of 16/s pseudo-random frequency changes, fronto-centrally maximal "mismatch-potentials" (MN1, MP2), were recorded. Both the MN1 and the MP2 were significantly shorter in latency when the steady frequencies formed an harmonic complex. Since the harmonic complex had a short overall periodicity, equal to that of the fundamental, while that of the inharmonic complex was much longer, the effect might be explained if the latencies of the mismatch-potential are related to periodicity. The perceptual grouping of harmonically related frequencies appears not to be a function of spectral domain analysis, reflected in the change-potentials, but of periodicity analysis, reflected in the mismatch-potentials Electronic Publication