Cortical evoked potentials in monozygotic twins and unrelated subjects: Comparisons of exogenous and endogenous components

Cortical evoked potentials to auditory stimulation were recorded in six pairs of monozygotic twins and six pairs of unrelated subjects matched for age and sex while they performed a stimulus detection task. The cortical potentials were coherently averaged, and the peak latencies of the exogenous (P₁, N₁, and P₂) and endogenous (N₂ and P₃) components of the average evoked potential (AEP) were investigated. It was hypothesized that latency of the exogenous components of the AEP would be similar in all matched pairs since the characteristics of these components depend primarily on the physical parameters of the stimulus. As endogenous components appear to be associated with a person's intentions, expectations, and decisions, we expected them to be more alike in twins than in unrelated individuals. Findings were in accord with the hypothesis. Latencies of the exogenous components were closely similar in all pairs of subjects. By contrast, latencies of the endogenous components were significantly (P0.001) more alike in twins than in unrelated subjects.This investigation was supported by United States Public Health Service Research Grant HD 02395 from the National Institutes of Health.     

Habituation of auditory evoked potentials in intracranial and extracranial recordings

Effects of stimulus repetition are investigated in short-term habituation experiments. In these experiments, trains of stimuli are applied with longer intervals of no stimulation between the trains. In scalp recordings, an amplitude and latency decrease of the auditory N100 is usually observed at the beginning of the train. This contrasts to a recent finding with intracranial recordings, exhibiting an effect on N100 amplitude, but not on its latency. In the current study, P50 and N100 were simultaneously recorded intra- and extracranially in epilepsy patients. The amplitudes of P50 and N100 decreased in both recordings, whereas the P50 latency was not significantly affected. A latency decrease was revealed for the extracranially recorded N100, but not for the intracranial N100. This dissociation between the intracranial and scalp recordings might be explained by a different sensitivity of the two measurements for N100 generators.     

Age-related differences in recovery cycle of auditory evoked potentials

Age-related differences in cerebral responsiveness to stimuli as reflected by the recovery cycle of cortical auditory evoked potentials (EPs) were investigated in healthy young and elderly adults. Pairs of identical tones separated by a fixed 350 msec interval were presented at rates of 1.0/sec, 0.5/sec, and 0.2/sec (inter-pair-intervals of 650, 1650, or 4650 msec). No age difference in the P1-N1 or N1-P2 amplitudes to either tone of the pair was present with the two faster stimulation rates. However, age-specific amplitude effects emerged for the slowest rate. The P1-N1 and especially the N1-P2 amplitude of the EP to the first as compared to that of the second tone was greatly enhanced among the young, but not as much among the elderly adults. Similarly, group differences in baseline to N1 and P2 amplitude measures of EPs to the first tone of the pair were most pronounced at the fastest stimulation rate. These data indicate clear differences in the recovery cycle of EPs between normal young and elderly subjects and demonstrate the applicability of the two-tone stimulation procedure in the assessment of cerebral responsivity in normal and pathologic populations.     

Age-related differences in recovery cycle of auditory evoked potentials

Age-related differences in cerebral responsiveness to stimuli as reflected by the recovery cycle of cortical auditory evoked potentials (EPs) were investigated in healthy young and elderly adults. Pairs of identical tones separated by a fixed 350 msec interval were presented at rates of 1.0/sec, 0.5/sec, and 0.2/sec (inter-pair-intervals of 650, 1650, or 4650 msec). No age difference in the P1-N1 or N1-P2 amplitudes to either tone of the pair was present with the two faster stimulation rates. However, age-specific amplitude effects emerged for the slowest rate. The P1-N1 and especially the N1-P2 amplitude of the EP to the first as compared to that of the second tone was greatly enhanced among the young, but not as much among the elderly adults. Similarly, group differences in baseline to N1 and P2 amplitude measures of EPs to the first tone of the pair were most pronounced at the fastest stimulation rate. These data indicate clear differences in the recovery cycle of EPs between normal young and elderly subjects and demonstrate the applicability of the two-tone stimulation procedure in the assessment of cerebral responsivity in normal and pathologic populations.     

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。     

孤独症患者脑干听觉通路功能的评估与研究

目的：研究孤独症患者脑干听觉通路的功能状态,并探讨其可能的构建模式。方法：采用脑干听觉诱发电位（BAEP）技术对36例孤独症患者（孤独症组）与27例对照者（对照组）进行测试,分析比较BAEP成分的组问差异。结果：孤独症组BAEP中双侧Ⅲ、V波的潜伏期（PL）和各峰间期（IPL）均较对照组延长,其中右侧Ⅲ波PL和双侧V波PL延长之组间差异显著（P〈O．05）,左侧Ⅲ-V波和双侧I—V波IPL延长组间差异显著（P〈0．05）。结论：孤独症患者存在脑干听觉通路功能异常或脑干功能发育不成熟。脑干传导时间延长产生的听觉信息传递失真与中枢性听觉紊乱可能是孤独症形成的构建模式之一。     

椎基底动脉供血不足患者的脑干听觉诱发电位与经颅多普勒检查

目的 :探讨椎基底动脉供血不足 (VBI)患者的脑干听觉诱发电位 (BAEP)与经颅多普勒(TCD)的相关性。方法 :对 5 8例临床诊断VBI眩晕的患者及 30例非VBI眩晕的患者进行BAEP和TCD检测。结果 :VBI组BAEP异常率为 5 9% ,TCD异常率为 6 1% ,χ2 检验差异无显著意义 :非VBI组BAEP异常率 8% ,TCD异常率为 47% ,χ2 检验差异有显著意义。VBI组BAEP及TCD皆异常者为 6 4/116 ,皆正常者为 2 3/116 ,两者占 75 % ;非VBI皆异常者为 4/6 0 ,皆正常者为 32 /6 0 ,两者占 6 0 %。结论 :结合BAEP及TCD检查结果有助于VBI的诊断 ,而单独的TCD结果不足以作为诊断依据。     

缺氧缺血性脑损伤新生大鼠脑干听觉诱发电位的动态变化

目的：探讨缺氧缺血性脑损伤新生大鼠脑干听觉诱发电位（BAEP）的动态变化。方法：30只出生13天的新生SD大鼠随机分为对照组和缺氧缺血组,每组15只。将出生后第13天新生大鼠结扎左侧颈总动脉后,置于含氧8％的低氧环境中3h建立缺氧缺血性脑损伤动物模型。出生后第14、20、27、37、47、57、67和77天检测大鼠的BAEP。结果：缺氧缺血组新生大鼠3h缺氧复氧1h后,表现为向左侧旋转,爬行时右侧后肢呈现拖步。出生后第14～47天缺氧缺血组大鼠BAEP波峰潜伏期（PL）和波峰间潜伏期（IPL）较对照组显著延长（P〈0．05或P〈0．01）,这些鼠的BAEP的PL及IPL均随年龄的增加而缩短,并且鼠可发育成熟。结论：缺氧缺血性脑损伤新生大鼠BAEP有显著的可逆性异常变化,其PL和IPL是动态监测与客观评价新生期缺氧缺血性脑损伤和听觉障碍的灵敏指标。     

52位正常人听觉P50诱发电位结果分析

目的 :探讨正常人听觉P5 0诱发电位特征。方法 :采用条件 (C) 试验 (T)刺激模式记录5 2位正常人的听觉P5 0诱发电位 ,分别对不同性别、不同年龄组之间P5 0的差异进行组间比较分析。结果 :①P5 0波峰潜伏期为 5 7 9± 7 6ms ,C P5 0与T P5 0潜伏期差为 3 1± 2 5ms。②T P5 0波幅较C P5 0波幅显著降低 ,试验 /条件 (T/C)率为 5 8 9± 12 7%。③女性组P5 0波幅较男性组显著升高 (P <0 0 5 ) ,潜伏期和T/C率均无差异 ;年龄组比较P5 0诸成分均无显著性差异。结论 :听觉P5 0诱发电位是一种具有抑制特征的电位活动。T/C率不受性别、年龄的影响 ,其变化可以反映大脑正常感觉门控的机能状态     

K-means clustering method for auditory evoked potentials selection

Surface auditory evoked potentials are generally recorded using a headset of 32, 64 or 128 electrodes, but the quality of the responses is quite heterogeneous on the scalp surface. In some contexts, such as the analysis of auditory evoked potentials recorded in radio-frequency fields, the signal quality is essential, and it appears pertinent to consider only a limited number of electrodes. Therefore, before analysing signals influenced by radio-frequency fields, it is necessary to consider the preliminary step of selecting the channels where auditory activity is strong. This step is often realised by human visual selection and can take a considerable time. In this paper, a simple k-means clustering method is proposed, to select automatically the important channels, and the results are compared with traditional methods of selection. The method detected channels that showed a concordance rate of 86.5% with the visual selection (performed by five individuals) and gave the same final selection (only two extra electrodes in the automatic case). Moreover, the time needed for this automatic selection was 100 times less than that for the visual selection, and also human variability was avoided.     

急性脑血管病患者脑干听觉诱发电位研究

目的研究急性脑血管病患者脑干听觉诱发电位（ＢＡＥＰ）变化。方法２４３例发病７天内的急性脑血管病患者和１２２例正常人进行ＢＡＥＰ检查。结果急性脑血管病患者ＢＡＥＰ异常率为８５．６％，明显高于正常对照组２５．４％，Ｐ＜０．０１。病情严重患者ＢＡＥＰ异常率为１００％，而轻、中型患者分别为７９．２％和８３．７％，与严重患者比较，Ｐ＜０．０１。ＢＡＥＰ异常主要表现为主波潜伏期和波间期延长，主波消失或分化不良。结论脑干听觉诱发电位可作为判断急性脑血管病的预后和观察病情变化的一项客观指标。     

偏头痛患者发作期脑干听觉诱发电位和瞬目反射检测

目的：观察偏头痛患者发作期脑干听觉诱发电位(BAEP)和瞬目反射(BR)改变。方法：对45例偏头痛发作期患者进行BAEP、BR检测。结果：BR和BAEP联合检测提示脑干病变者31例，占69％；BAEP、BR检测提示听神经、三叉神经传入通路功能障碍和面神经传出通路功能障碍共26例，占58％，其中三叉神经传入通路障碍21例，占81％。结论：偏头痛发作期存在着以脑干和三叉神经为主的神经功能障碍．与血管舒缩功能障碍很可能互为因果、相互影响。     

海风藤对犬脑干缺血后BAEP的影响

目的观察海风藤对犬脑干缺血后脑干听觉诱发电位（ＢＡＥＰ）的影响。方法建立犬脑干缺血模型，给药组和对照组各２０只犬，分别于阻断基底动脉前３ｈ向十二指肠注入海风藤溶液（按０．３ｇ／ｋｇ）和等体积生理盐水，于缺血前和缺血后０．５、３、６和１２ｈ分别记录ＢＡＥＰ。结果给药组ＢＡＥＰ的Ⅰ、Ⅲ、Ⅴ波潜伏期和Ⅰ－Ⅲ、Ⅲ－Ⅴ、Ⅰ－Ⅴ波峰间期明显缩短。结论海风藤可改善犬脑干对缺血的耐受程度，减小半暗带的范围，减轻病变的程度。     

Modulation of steady-state auditory evoked potentials by cerebellar rTMS

Steady-state auditory evoked responses (SSAER) obtained via electroencephalography (EEG) co-vary in amplitude with blood flow changes in the auditory area of the cerebellum. The aim of the present EEG study was to probe the cerebellar role in the control of such SSAER. For this purpose, we investigated changes in SSAERs due to transient disruption of the cerebellar hemisphere by repetitive transcranial magnetic stimulation (rTMS). SSAERs to click-trains of three different frequencies in the gamma-band (32, 40 and 47 Hz) were recorded from 45 scalp electrodes in six healthy volunteers immediately after 1-Hz rTMS and compared to baseline SSAERs assessed prior to magnetic stimulation. Cerebellar rTMS contralateral to the stimulated ear significantly reduced the amplitude of steady-state responses to 40-Hz click-trains and showed a tendency to reduce the amplitude to 32-Hz click-trains. No effects were observed for 47-Hz click-trains, nor for magnetic stimulation of the cerebellum ipsilateral to auditory stimulation or after sham stimulation. Our results suggest that interference with cerebellar output by rTMS modifies functional activity associated with cortical auditory processing. The finding of maximum effects on 40-Hz SSAERs provides support to the notion that the cerebellum is part of a distributed network involved in the regulation of cortical oscillatory activity and points at some frequency-specificity for the control of auditory-driven neuronal oscillations.     

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.     

Multichannel electroencephalographic assessment of auditory evoked response suppression in schizophrenia

Reduced auditory evoked response (AER) suppression in a paired-stimulus paradigm (where suppression equals the difference between S1 and S2 amplitudes divided by S1 amplitude) may index genetic liability for schizophrenia. The present report is a multiple-channel electroencephalographic (EEG) study of AER suppression among 20 normal and 20 schizophrenia subjects. The typical paired-stimulus paradigm was used to evoke time-locked AERs. AER responses were scored at P50 and N100 in the time domain using both single (Cz) and multichannel data (after reduction using principal components analysis, PCA), and were scored for information in the gamma (20–50 Hz) and low-frequency (1–20 Hz) ranges using multichannel information (also after PCA). The time domain analyses demonstrated that schizophrenia patients differ from normal in amplitude of response to the first, but not to the second, stimulus for both P50 and N100. The frequency domain data demonstrated that schizophrenia patients differed from normal on amplitude of the low-frequency response (LFR) to the first, but not to the second, stimulus. The groups did not differ significantly on amplitudes of the gamma-band responses. Group separations were largest for the multichannel N100 and LFR data, with the LFR demonstrating a modestly better risk ratio for differentiating schizophrenia from normal subjects. The present results suggest two novel differences from previous AER suppression studies: (1) S1 amplitudes largely determine differences between normal and schizophrenia groups on AER suppression, and (2) frequency domain analyses may provide important complimentary information when studying AERs in schizophrenia. Electronic Publication     

Auditory and somatosensory event-related brain potentials in early blind humans

Previous event-related potential (ERP) studies have suggested a possible participation of the visual cortex of the blind in auditory processing. In the present study, somatosensory and auditory ERPs of blind and sighted subjects were recorded when subjects were instructed to attend to stimuli of one modality and to ignore those of the other. Both modalities were stimulated with frequent (standard) and infrequent (deviant) stimuli, which differed from one another in their spatial locus of origin. In the sighted, deviant stimuli of the attended modality elicited N2 type of deflections (auditory N2b and somatosensory N250) over the lateral scalp areas. In contrast, in the blind, these ERP components were centroposteriorly distributed, suggesting an involvement of posterior brain areas in auditory and somatosensory stimulus discrimination. In addition, the mismatch negativity, elicited by deviant auditory stimuli even when the somatosensory stimuli were attended, was larger in the blind than in the sighted. This appears to indicate enhanced automatic processing of auditory stimulus changes in the blind. Thus, the present data suggest several compensatory changes in both auditory and somatosensory modalities after the onset of early visual deprivation.     

体温过低对大鼠脑干听觉诱发电位和中潜伏期反应的影响

目的：探讨体温过低对大鼠脑干听觉诱发电位（BAEP）和中潜伏期反应（MLR）的影响。方法：计算机平均叠加技术颅表记录大鼠BAEP和MLR，体表物理降温法逐步降低大鼠体温，传感探头式数字体温计监测大鼠直肠温度，体温每降低1 ℃测试1次BAEP和MLR，观察波峰潜伏期（PL）和波幅的变化及各波消失的临界体温。结果：随体温逐渐降低（36 ℃-22 ℃），BAEP和MLR各波PL逐步延长；BAEP Ⅰ、Ⅱ、Ⅳ 3主波和MLR N1、P3 2主波的波幅在体温过低至26 ℃以下时方先后出现显著降低；BAEP和MLR各波在体温19 ℃-21 ℃全部消失，且两者同步消失。结论：体温过低对大鼠BAEP和MLR均有显著影响。     

Changes in auditory evoked brain potentials during ultra-low frequency whole-body vibration of man or of his visual surround

Summary Auditory evoked brain potentials (AEP) were recorded from nine healthy male subjects during three types of condition: A — subject and visual field stationary; B — subject vibrated (z-axis, 0.6 Hz, 1.85 ms^–2 rms), visual field stationary; C subject stationary, visual field vibrated (as for B). The visual surround was confined to a checkerboard pattern in front of the subject. Auditory stimuli (1000 Hz, 86 dB, inter-stimulus interval 7 s) were delivered via headphones to evoke AEP. Vibration-synchronous activity in the EEG was eliminated by a subtraction technique. In comparison with condition A, conditions B and C caused an attenuation of P2 and N1P2 components of AEP together with an increased latency of N1. Effects of conditions B and C did not differ. Direct vestibular stimulation and mechanisms specific for whole-body vibration were rejected as modes of action. The AEP-changes and the subjective evaluation of experimental conditions, arousal and performance, as well as symptoms of kinetosis (motion sickness) suggest a sensory mismatch, leading to a latent kinetosis with de-arousal, as the dominating mechanism by which the processing of information was affected. This suggestion was supported by an additional pilot study. Under real working conditions a similar effect can be expected during relative motion between the driver and his visual surround, i.e. even with perfect vibro-isolation of the driver's seat.This work was done by the Temporary Research Team on Combined Effects of Noise and Vibration of the Council of Mutual Economic Assistance of the East European Countries