The relation between conduction velocity and axonal length

Motor evoked potentials (MEPs) obtained by electrical root stimulation and F waves were used to examine the proximal nerve conduction velocity (CV) to tibialis anterior (TA), extensor digitorum brevis (EDB), flexor carpi radialis (FCR), and abductor pollicis brevis (APB) muscles in 40 humans. By subtracting motor latencies obtained by stimulating the peripheral nerve at the same point from the F-wave and MEP latencies, we could measure the CV over identical proximal segments. It was found that proximal CV to TA and FCR was significantly higher than to EDB and APB, respectively. Combining the data of the proximal CV to all four muscles in relation with axonal length resulted in a highly significant inverse relationship (r² = 0.77). Thus the axonal length explained to a large extent the higher CV of the arm nerves and also the inverse relation between body height and CV. The distal CV was always lower than proximal CV; however, there was no support for an additional effect of this gradient in explaining the relationship between CV and height since it was constant for all body heights. © John Wiley & Sons, Inc.     

Human slow-wave sleep and the cerebral cortex

SUMMARY  Recent hypotheses about the roles of human slow-wave sleep (hSWS—delta EEG activity) are appraised. The possible linkage between hSWS and the functions of the prefrontal cortex (PFC) are explored with respect to normal subjects and to disorders involving PFC deficits.     

基于线性调频信号的高帧率超声成像系统

基于有限衍射波束的高帧率超声成像系统能实现快速成像，但由于仅通过一次发射事件成像，信噪比较低，本研究针对该问题提出一种改进方案。它采用合成孔径雷达中所使用的线性调频信号作为激励信号，在接收端则利用线性调频信号的脉冲压缩比等于信号的时间带宽积的特征，将接收信号通过匹配滤波器处理。结果表明该方案不仅能显著提高成像系统的信噪比，改善重构图像的质量，增加成像深度，而且不损失分辨率。     

Changes of the beat amplitude power after partial left ventriculectomy and coronary artery bypass grafting

Partial left ventriculectomy (PLV) was originally introduced as a new surgical approach by patients with an end stage of cardiac disease. Coronary artery bypass grafting (CABG) is a standard procedures used in cardiac surgery. Multichannel ECG (MECG) measurements and body surface mapping (BSM) were used to analyse the normalised beat amplitude power maps (BAM) that reflect an overall cardiac activity. The resulting BAMs show that the amplitude of cardiac signals decrease for approximately 30% after the PLV and stay in the same level during the postoperative monitoring interval while after CABG no significant changes in BAM have been observed. In addition the electrodes from the body surface area above the left ventricle, where surgery was performed, show significant changes in beat amplitudes.     

The relationship between women's subjective and physiological sexual arousal

Previous literature presents discordant results on the relationship between physiological and subjective sexual arousal in women. In this study, the use of hierarchical linear modeling (HLM) revealed a significant concordance between continuous measures of physiological and subjective sexual arousal as assessed during exposure to erotic stimuli in a laboratory setting. We propose that past studies that have found little or no association between the two measures may have been in part limited by the methodology and statistical analyses employed.     

THE INTERACTION OF RESPONSES IN THE BRAIN TO SEMANTIC STIMULI

Long time-constant EEG recording during paired stimuli has led to the discovery of the contingent negative variation or expectancy wave (Walter, 1964). This effect is produced when a conditional stimulus signals that an imperative stimulus demanding action, decision, or attention will follow at a short, constant time interval. Symbolic and meaningful stimuli were presented to subjects tachistoscopically, and the evoked responses in the brain were electronically averaged. The cerebral evoked responses to such psychological stimuli are more complex than to flashes. A slow negative DC potential shift (CNV) was seen during the interval between an auditory ready signal and the visual exposure if recognition of the stimulus was required, or if it was interesting. Following the visual exposure, a slow positive DC shift occurred. The method has been developed to study the brain responses to psychological stimuli. The amplitude of the responses relates to the information content and subjective factors rather than to the physical strength of the stimulus.     

冲击伤肺肋面的平行出血条纹

本文采用部分肋骨切除术,切除15只家兔双侧5、6、7、8肋中任一肋距脊柱约2cm处一段长约1cm的肋骨。一周后对受冲击波致伤的肺肋面的出血情况进行解剖观察,发现肺肋面的出血条纹呈“工”字形,从而为冲击伤肺肋面的平行出血条纹是肋间压痕这一观点找到了直接的实验证据。     

Two Measures of Auditory Evoked Response Amplitude and Their Relationship to Background EEG

All-night sleep EEG and auditory evoked responses (AERs) were recorded in 8 children whose ages ranged from 27 to 60 months. EEG intensity was measured by means of a Drohocki-type integrator. Two measures of evoked response amplitude were calculated: the peak-to-peak amplitude of the P₂N₂ component, and a multiple-component amplitude measure of the first 500 msec of the response. Both amplitude measurements were found to correlate well with each other. Changes in EEG intensity between subjects were not correlated with changes in AER amplitude, but a number of correlations between AER amplitude and EEG intensity were found within individual subjects. Further analysis suggested the latter finding might be a result of the presence of “unaveraged’EEG in individual AER plots. It is concluded that little correlation exists between AER amplitude and EEG intensity in children during sleep.     

Pulse wave reflection at the collapsed segment of an artery in Riva-Rocci's method

Summary The contours of pressure and flow of a pulse wave arriving at the entrance of a collapsed segment of an elastic tube can be described by application of the basic laws of reflection. The collapsed segment acts like a valve. It is opened by the pressure of the pulse wave when the pressure within the tube becomes higher than the collapse pressure, i.e. the pressure exerted on the segment from outside. This opening of the collapsed segment suddenly changes the sign of the pulse wave reflection from positive to negative; thus a typical contour change of the pulse proximal to the segment is observed. The most obvious effect is a reduction of the pulse pressure. The extent of this reduction is a function of the collapse pressure.A typical example of this phenomenon can be observed in an artery proximal to the segment which is collapsed due to the pressure exerted by an inflated Riva-Rocci cuff. The effect is explained by the assumption that the sign of reflection changes when the pressure of the pulse wave crosses the level of the cuff pressure. This explanation is supported by the results of model experiments.     

人体胆结石高能震波碎石的动物实验

目的　研究人体 3种胆结石在一定能量下 ,冲击次数和能量的关系 ,确定不损伤胆囊和小肠内膜的能量安全阈值 .方法　犬胆囊和小肠内放入固醇石、混合石和色素石 ,在不同的输出电压下 ,放电碎石 .结果　固醇石、混合石和色素石破碎所需的能量不同 ,在同样电压下 ,固醇石所需的次数最少 ,混合石次之 ,色素石最多 ;病理检查表明 ,在电压 <15 k V时 ,胆囊和小肠粘膜处 ,细胞膜轻度充血 ,出现小出血点 .当电压 >15 k V后 ,粘膜有脱落 ,膜下组织水肿 .结论　电压具有依赖性 ;该仪器临床应用的冲击电压应小于 15 k V