Stability of Late Event-Related Potentials: Topographical Descriptors of Motor Control Compared with the P300 Amplitude

The P300-amplitude evoked with an acoustic oddball-paradigm is considered the most stable late event-related potential (ERP). This amplitude-index has become a standard parameter in electrophysiology. Recently, a robust ERP-parameter (NoGo-anteriorization, NGA) has been introduced, which reflects spatial brain electrical changes in relation to execution and inhibition of a motor response elicited with a Continuous Performance Test (CPT). The current study refers to the stability of this new topographical ERP-parameter compared to the stability of the classical P300-amplitude. For that purpose, 12 healthy subjects were investigated with both paradigms during recording of a 21-channel EEG. Analysis of the resulting ERPs revealed a very high stability for both, topographical and amplitude index: In every single subject, the brain electrical fields were characterized by a more anterior location in the NoGo- compared to the Go-condition (=NGA) and by higher amplitudes after target compared to distractor condition. T-tests, analyses of the effect size and of the power revealed equivalent differences between the two contrasting conditions for the topographical compared to the amplitude index. These results indicate that the stability of the topographical ERP-parameters elicited with the CPT is sufficient for an electrophysiological standard-index. The possibility to elicit a robust and specific spatial brain activation with the CPT is an ideal completion to the classical P300 amplitude effect and, therefore, hopefully will be a useful expansion of the standard paradigms in electrophysiological laboratories.     

Electrophysiological Response to Ethanol in P and NP Rats

Event-related potentials (ERPs) have been successfully used in human subjects to evaluate alcoholics as well as those at risk for the future development of alcoholism. In the present study, two lines of rats, those with a preference for ethanol consumption (P) and those not preferring (NP) to drink ethanol were studied using ERP-producing stimuli. Rats were implanted with electrodes in the frontal cortex and dorsal hippocampus (DHPC). A passive auditory "oddball" paradigm was used to record ERP responses following saline and two doses (0.5, 1.0 g/kg) of ethanol. P and NP rats differed under the saline condition in that P rats had smaller N1-like ERP components and larger P2 waves in both cortex and hippocampus. P and NP rats were also found to differ in response to ethanol administration. NP rats evidenced dose-dependent reductions in ERP component amplitudes such as the N1 recorded from cortical sites. P rats did not have such reductions in N1 amplitudes and in fact, displayed increased N1 amplitudes in hippocampal sites. These studies provide further electrophysiological evidence that rats with a genetically influenced preference for ethanol consumption differ from nonpreferring rats at baseline and have a less intense depressant or more stimulating response to ethanol challenge.     

针刺不同穴组对胫后神经SEPs痛成分的影响

目的 :比较不同穴组的镇痛作用。方法 :采用电刺激正常人下肢胫后神经获得痛相关成分P2 50 -N350 复合波作为反映疼痛的客观指标 ,观察针刺秩边、次穴与合谷、三阴交穴对痛相关成分P2 50 -N350 波幅、潜伏时的变化影响。结果 :两组配穴都具有镇痛作用 ,但镇痛程度差异明显 ,分别为P <0 0 0 1,P <0 0 5。结论 :对于产妇产程缓慢、子宫收缩无力者 ,应优先选择合谷、三阴交配穴 ;对于产程中以疼痛为主的产妇 ,应优先选择秩边、次配穴以有效地抑制疼痛 ,减轻产妇痛苦 ,保证产妇的顺利分娩。     

不同穴位针刺对暂时性局部脑缺血大鼠皮层体感诱发电位和脑梗塞体积的影响

观察不同穴位针刺对暂时性局部脑缺血的作用，采用皮层体感诱发电位测定和ＴＴＣ染色法，结果表明，电针能促进皮层体感诱发电位的恢复，可使脑缺血后脑梗塞体积减小，且督脉穴位针刺在促使脑缺血后皮层体感诱发电位恢复上可能具有相对较强的作用。     

孤独症儿童脑干听觉诱发电位及耳声发射研究

目的探讨孤独症对听觉系统功能的影响,为临床诊治提供理论依据。方法对20例孤独症患儿进行听觉脑干诱发电位（auditory brainstem response,ABR）及畸变产物耳声发射（distortion Product otoacoustic emission,DPOAE）测试,设立同年龄段正常组进行对照研究。结果①孤独症组ABR双耳Ⅴ波潜伏期、右耳Ⅰ～Ⅴ波间期、Ⅲ～Ⅴ波间期延长,与对照组比较有显著性差异（P〈0．05）;②孤独症组DPOAE异常率增高,1kHz及1．5kHz平均幅值及1kHz引出率降低,与对照组比较有显著性差异（P〈0．05）。结论孤独症儿童ABR潜伏期延长,DPOAE测试异常率增高,提示脑干听觉通路传导异常,可能是引起孤独症儿童广泛感觉系统发育障碍,使言语、认知、社会等方面异常发育的原因之一。     

Neurophysiological adaptations to spaceflight and simulated microgravity

Changes in physiological functions after spaceflight and simulated spaceflight involve several mechanisms. Microgravity is one of them and it can be partially reproduced with models, such as head down bed rest (HDBR). Yet, only a few studies have investigated in detail the complexity of neurophysiological systems and their integration to maintain homeostasis. Central nervous system changes have been studied both in their structural and functional component with advanced techniques, such as functional magnetic resonance (fMRI), showing the main involvement of the cerebellum, cortical sensorimotor, and somatosensory areas, as well as vestibular-related pathways. Analysis of electroencephalography (EEG) led to contrasting results, mainly due to the different factors affecting brain activity. The study of corticospinal excitability may enable a deeper understanding of countermeasures' effect, since greater excitability has been shown being correlated with better preservation of functions. Less is known about somatosensory evoked potentials and peripheral nerve function, yet they may be involved in a homeostatic mechanism fundamental to thermoregulation. Extending the knowledge of such alterations during simulated microgravity may be useful not only for space exploration, but for its application in clinical conditions and for life on Earth, as well.     

听性脑干反应与40Hz听觉相关电位综合评估听觉阈值

目的 探索应用听性脑干反应(auditory brain stem response,ABR)和40Hz听觉相关电位(40Hz auditory event related potential,40Hz AERP)来客观评估听阈的最佳方法.方法 对120例受试者分别测出其平均听阈和ABR阈值、40Hz AERP阈值,共获得资料可靠完整的86耳用于实验分析.将86耳根据听力曲线的类型分为下降型29耳、上升型20耳和水平型37耳三种.用SPSS软件分别对3组数据进行统计学处理,并进行多元回归分析,建立三种数学模型,并进行简化和检验.最后另选10例新的受试者对得到的公式进行均方差可靠性检验.结果 3组平均听阈与ABR阈值和40Hz AERP阈值具有显著线性相关性(r2=0.932,0.944,0.934).建立的三种模型分别为:水平型,平均听阈=ABR阈值;下降型,平均听阈=1/3(40HzAERP) 2/3ABR;上升型,平均听阈=2/3(40HzAERP) 1/3ABR.均方差检验显示公式法优于ABR法.结论 利用ABR阈值和40Hz AERP阈值通过三种回归方程较单纯应用ABR阈值能够更准确的估计受试者的平均听阈,可以尝试用于评估婴幼儿及不能主动配合的受试者的听阈.     

听神经瘤的耳声发射观察

目的 观察和分析听神经瘤的耳声发射特点,为评估听神经瘤患者的耳蜗功能和选择保护听力的术式提供参考依据.方法 对20例（22耳）听神经瘤患者行纯音听阈、阻抗、听性脑干反应（auditory brainstem response,ABR）、诱发性耳声发射（evoked otoacoustic emissions,EOAE）测试及CT和（或）MRI扫描,能引出EOAE的瘤耳检测其自发性耳声发射（spontaneous otoacoustic emissions,SOAE）和传出抑制功能.结果 28.57%听神经瘤耳能引出EOAE,按其畸变产物耳声发射（distortion product otoacoustic emissions,DPOAE）特点分为三型：①“耳蜗型”3耳;②“非耳蜗型”2耳;③“混合型”1耳;“非耳蜗型”耳能引出强大的SOAE;能引出EOAE的6耳均有内侧橄榄耳蜗传出系统功能障碍.结论 EOAE可精确分析听神经瘤患者的耳蜗（外毛细胞）功能,部分听神经瘤病人存在“离断耳”现象.耳声发射（otoacousticemissions,OAE）在诊断重度感音神经性聋（包括听神经瘤病人）方面有一定潜能.     

Effects of methylprednisolone on the neural conduction of the motor evoked potentials in spinal cord injured rats

Methylprednisolone(MP), a glucocorticoid steroid, has an anti-inflammatory action and seems to inhibit the formation of oxygen free radicals produced during lipid peroxidation in a spinal cord injury(SCI). However, the effects of MP on the functional recovery after a SCI is controversial. The present study was conducted to determine the effects of MP on the recovery of neural conduction following a SCI. A SCI was produced using the NYU spinal cord impactor. A behavioral test was conducted to measure neurological disorders, and motor evoked potentials (MEPs) were recorded. According to the behavioral test, using BBB locomotor scaling, MP-treated animals showed improved functional recoveries when compared to saline-treated animals. MEP latencies in the MP-treated group were shortened when compared to those in the control group. Peak amplitudes of MEPs were larger in the MP-treated group than those in the control group. The thresholds of MEPs tended to be lower in the MP-treated group than those in the control group. These results suggest that MP may improve functional recovery after a SCI.     

Cerebral Response to Electric Stimulation of the Colon and Abdominal Skin in Healthy Subjects and Patients with Irritable Bowel Syndrome

Background: Visceral hyperalgesia may play an important part in the pathophysiology of the irritable bowel syndrome (IBS). We investigated the neuronal afferent pathways in healthy volunteers and IBS patients by recording evoked potentials (EPs) elicited by electrical stimulation of the colon and abdominal skin inside and outside the referred pain area. Methods: Six healthy subjects and nine IBS patients met the inclusion criteria. Morphology and topography of EPs to painful electrical stimuli were estimated in the rectosigmoid junction and on the skin inside/outside the referred pain areas. Results: The EPs to painful stimuli of the gut showed a shorter latency and a smaller amplitude of the first positive peak (P1) in the IBS group. The controls had a mid-latency frontal positive component after 100 ms, whereas no reliable early activation was seen in the IBS patients. In controls, a single late (> 150 ms) positive component was seen, whereas the late component was biphasic in the IBS group. The EPs to painful stimuli of the two skin areas differed in IBS patients, but not in controls. Conclusion: Differences in the EPs to electrical painful stimulation of the sigmoid colon and skin inside/outside the experimentally evoked referred pain area were seen comparing healthy subjects and IBS patients. The results indicate altered central nervous system responses.