磁刺激运动诱发电位在腰椎间盘突出所致的腰骶神经根病变中的应用研究

在35例有L5和／或S1神经根损害表现的腰椎间盘突出患者腰椎区进行磁刺激运动诱发电位（MEP）检查，测定、记录胫前肌、展肌和小趾展肌MEP的起始潜伏期（OL）。结果显示，35例中至少有一条总侧肌肉MEP异常33例（94．3％）。在L4－5椎间盘突出中，以胫前肌的MEP异常为主；在L5－S1椎间盘突出中，以小趾展肌的MEP异常为主。表明腰椎区MEP检查对腰椎间盘突出所致的腰骶神经根病变较为敏感，可为临床诊断提供可靠依据并有助于定位诊断。     

Effects of intravenous L-acetylcarnitine on retinal oscillatory potentials

L-acetylcarnitine is a compound with cholinergic properties and putative action on the visual system and the glucose metabolism. Ten healthy, emmertropic volunteers (age range: 21 to 28 years) were studied. Each subject was administered 5, 10, and 30 mg/kg acute intravenous doses of L-acetylcarnitine and matching placebo. Retinal oscillatory potentials to full-field flash stimulation were recorded before and 30, 60, and 120 min after administration. A systematic reduction of the implicit time of the P2 and N2 oscillatory potential components was observed after administration of the 10 and 30 mg/kg doses: significant changes were not evident at the 5 mg dose or after placebo. The latency reduction was significantly correlated with the postdrug increment of the L-acetylcarnitine plasma concentration. No other systematic modification in latency of amplitude was observed.The results were presented in part at the XXV I.S.C.E.V. Symposium, Sarasota (Florida), April 26–30, 1987.     

Movement-related potential measures of different modes of movement selection in Parkinson's disease

Movement-related potentials were recorded preceding self-paced voluntary movements in patients with Parkinson's disease and in healthy subjects of the same age group. We compared the Readiness Potential preceding joystick movements in a fixed direction and preceding joystick movements in freely selected directions. In normal subjects the Readiness Potential amplitude was higher preceding freely selected movements than preceding movements in a fixed direction. The Readiness Potential in Parkinson patients failed to be modified by the different modes of movement selection. The modulation of the Readiness Potential by different ways of preparing for movement might be due to the supplementary motor area (SMA) being more strongly engaged by tasks requiring internal control of movements than by tasks that are externally structured. The results suggest that this task-dependent variation of SMA activity is reduced in Parkinson's disease. A failing capacity to adapt SMA activity to different task demands has previously been suggested by evidence from positron emission tomography studies using similar tasks.     

The composite N1 component to gaps in noise.

OBJECTIVE: To indicate whether the double peaked N(1) to gaps in continuous white noise is a composite of onset and offset responses to transients or whether it reflects higher processing such as change or mismatch detection and to assess the role of attention in this process. METHODS: Evoked potentials were recorded to two binaural stimulus types: (1) gaps of different durations randomly distributed in continuous white noise; and (2) click pairs at intervals identical to those between gap onsets and offsets in the continuous noise stimulus. Potentials to these stimuli were recorded while subjects read a text and while detecting gaps in noise or click pairs. RESULTS: Potentials were detected to all click pairs and to gaps of 5 ms or longer, corresponding to the subjects' psychoacoustic gap detection threshold. With long gap durations of 200-800 ms, distinct potentials to gap onset and gap offset were observed. The waveforms to all click pairs and to offsets of long gaps were similar and single-peaked, while potentials to gaps of 10 ms and longer, and potentials to onsets of long gaps were double-peaked, consisting of two N(1) negativities, 60 ms apart, irrespective of gap duration. The first (N(1a)), was more frontal in its distribution and similar to that of clicks. The second (N(1b)) peak's distribution was more central/temporal and its source locations and time course of activity were distinct. No effects of attention on any of the varieties and constituents of N(1) were observed. CONCLUSIONS: Comparing potentials to gap onsets, to click pairs and to gap offsets, suggests that potentials to gap onsets involve not only sound onset/offset responses (N(1), N(1a)) but also the subsequent pre-attentive perception of the cessation of an ongoing sound (N(1b)). We propose that N(1b) is distinct from change or mismatch detection and is associated with termination of an ongoing continuous stimulus. We propose to call it the N(egation)-process. SIGNIFICANCE: A constituent of the N(1) complex is shown to be associated with the pre-attentive perception of termination of an ongoing stimulus and to have distinct scalp distribution and intracranial sources.     

Differential modulation of the short- and long-latency somatosensory evoked potentials in a forewarned reaction time task.

OBJECTIVE: We investigated modulation of the short- and long-latency somatosensory evoked potentials (SEPs) in a forewarned reaction time task. METHODS: A pair of warning (auditory) and imperative stimuli (somatosensory) was presented with a 2 s interstimulus interval. In movement condition, subjects responded by grip movement with the ipsilateral hand to the somatosensory stimulation when the imperative stimulus was presented. In counting condition, they silently counted the number of imperative stimuli. The SEPs in response to the imperative stimuli were recorded. RESULTS: Frontal N30 and central N60 amplitudes were significantly smaller in the movement than in the counting or rest conditions. None of the short-latency components differed between the counting and rest conditions. In contrast to the short-latency components, P80 was significantly larger in the counting than in the rest condition, and showed a further increase from the counting to the movement condition. The N140 amplitude was significantly larger in the movement than the rest condition, but was not changed between the counting and the rest conditions. CONCLUSIONS: The attenuation of the frontal N30 and central N60, and the enhancement of the P80 and possibly the N140 resulted from the centrifugal mechanism. The present findings may show the different effects of voluntary movement on the early and subsequent cortical processing of the relevant somatosensory information requiring a behavioral response. SIGNIFICANCE: The present study demonstrated the differential modulation of short- and long-latency components of SEPs in a forewarned reaction time task.     

Correlation with age and sex of flash-evoked electroretinogram and retinal oscillatory potentials recorded with skin electrodes

Electroretinograms and retinal oscillatory potentials to full-field flash stimulation were recorded by dermal electrodes in a population of subjects (1 to 84 yrs) balanced for age and sex (119 females, 133 males), without evidence or history of ocular and/or relevant systemic diseases. The electroretinogram latencies and b-wave amplitude increased, while the a-wave amplitude decreased linearly with age. The oscillatory potential amplitude initially increased, to decrease approximately at the age of 50, with an inverted U-shaped distribution.Presented in part at the XXV ISCEV Symposium, Sarasota (Florida), April 26–30, 1987.     

碘杂环化合物对离体豚鼠心乳头肌动作电位和收缩力的作用

采用细胞内微电极记录技术,同步观察了3,6-[二甲氨基]-二苯并碘因甲酸盐(IHC-64)对豚鼠心乳头肌细胞动作电位和收缩力的作用。50μmol/L IHC-64抑制心肌收缩力,而不影响快反应动作电位。增加IHC-64浓度,动作电位0相最大峰值(APA)、除极速率(dp/dt_(max))和复极50％和90％时程(APD_(50)、APD_(90))被明显抑制。IHC-64抑制慢反应动作电位,提高细胞外钙浓度可拮抗这种抑制。结果提示,IHC-64主要抑制慢Ca~(2+)内流,同时也部分抑制快Na~+内流,它可能是一种新型B类钙通道阻滞剂。     

兔坐骨神经挤压伤的MRI与SEP对比研究

目的:探讨磁共振成像和体感诱发电位以及两者结合在坐骨神经急性挤压伤中的诊断价值。方法:24只兔按钳夹力的不同随机分为A、B两组,左后肢为损伤侧,右后肢为对照侧,建立坐骨神经急性挤压伤模型,于伤后1、2、4、8周行MR扫描,同时行双侧体感诱发电位检查。结果:损伤侧24条神经,有23条MR显示异常,诊断正确率95.8%,假阴性率4.17%(1/24);24条损伤侧坐骨神经,有22条SEP显示异常,诊断正确率91.6%,假阴性率8.3%(2/24)。MRI与SEP对神经损伤的正确诊断率无统计学差异(P>0.05)。MRI与SEP结合起来,24条损伤神经均显示异常,诊断正确率100%。结论:MR与SEP检查可无创、准确地判断神经损伤,两者结合可明显提高神经损伤的正确诊断率,重复性好,可作为神经损伤的较好诊断手段。     

65例多发性硬化患者的临床分析

目的总结多发性硬化(MS)患者的临床特点(精神情感障碍)以及脑脊液、诱发电位、影像学改变进行分析。方法回顾分析65例MS患者的有关临床和实验室资料。结果65例中,男17例,女48例;年龄16~68岁,平均(36.5±14.1)岁,男女比为1∶2.8。MS首发及常见症状为感觉异常、肢体无力、视力减退及括约肌功能障碍,病变部位以脊髓受累最多见,部分患者存在精神情感障碍。结论出现感觉异常有助于MS早期诊断,诱发电位及MRI有助于发现亚临床病变;括约肌功能异常多见,可能与脊髓受累较多有关;MS患者的精神情感应受人们关注。