穴位磁刺激对汽车驾驶员心率变异性的影响分析

汽车驾驶员在长期驾驶情况下，尤其振动条件下，常表现不同的生理，心理功能障碍或紊乱，影响驾驶员身心健康并诱发交通事故，。本文应用心率变异性及主观评估。分析了竖直振动条件下穴位磁刺激对心率变异性的影响。持续应激条件下，实验者心率变异性（HRV）表现出明显的变化，如交感神经张力增加，迷走神经张力降低，施加穴位磁刺激后，实验者迷走神经兴奋性提高，精神紧张及疲劳程度降低。因此穴位磁刺激可缓解驾驶疲劳，减少持续应激的不利影响，有利于保护驾驶员身心健康及提高汽车驾驶安全性。     

汽车驾驶员模拟精神负荷与心率变异性的相关性分析

汽车驾驶员精神负荷状态下的心率变异性分析对于揭示驾驶员职业应激特点,预防驾驶员职业疾病,保护驾驶员身体健康及提高行驶安全性有重要意义.本文在实验室条件下采用警惕任务代替驾驶员实际精神负荷,应用功率谱分析研究了模拟应激状态下心率变异性(TP,LF,HF,LF/HF)的变化趋势.本实验中,心率变异性频域主要指标如LF、HF、LF/HF表现出显著的线性趋势.结果表明,健康人在持续应激状态下,交感神经张力显著增加,迷走神经张力显著降低.实验结果表明HRV与精神疲劳具有较好的相关性.     

磁刺激神门穴脑电信号的样本熵分析与诱发电位的研究

研究用经颅磁刺激仪在不同频率下刺激肢体神门穴,在安静、磁刺激、假刺激、假穴4种不同状态下脑电信号的样本熵值以及脑电信号诱发电位的特征。对8名被试者进行实验,实验分为4组即安静、磁刺激、假刺激、假穴,测量3种不同频率(0.5、1、3 Hz)刺激下的脑电信号并计算样本熵值,对刺激后的脑电信号诱发电位进行了分析。结果显示,1 Hz与0.5 Hz磁刺激脑电信号样本熵没有明显变化(P0.05);3 Hz时4种状态下的脑电信号样本熵变化较明显(P0.05),磁刺激组和假穴组明显高于安静组和假刺激组,且磁刺激组略低于假穴组;3 Hz磁刺激无诱发电位;而假穴组产生明显体感诱发电位等其他诱发电位。实验表明,对人体神门穴进行磁刺激对脑电信号有明显抑制,与进行针刺或电刺激同样具有调节神经机能的作用。     

汽车驾驶员驾驶过程中的心率变异性功率谱分析

驾驶疲劳是影响汽车乘坐舒适性及交通安全的重要因素。汽车驾驶员在长期驾驶情况下，尤其振动条件下，常表现出不同的生理、心理功能障碍或紊乱，影响驾驶员身心健康并诱发交通事故。本研究应用心率变异性功率谱分析并结合主观评估，分析了模拟实际驾驶条件下实验者的心脏自主神经功能状态。持续应激条件下，实验者心率变异性(HRV)表现出明显的变化，如交感神经活动性增加，迷走神经活动性降低。实验结果表明心率变异性(HRV)是精神负荷敏感的指标，可用于定量评估驾驶疲劳。     

子宫收缩对胎儿心率变异性非线性的影响

目的 对不同子宫收缩状态下.分析胎儿心率变异性的非线性混沌强度.方法 采用非线性滴定方法,计算胎儿心率变异性的噪声极限,即非线性混沌强度;另用近似熵方法计算宫缩状态下胎儿心率变异性的复杂性.结果 统计结果表明宫缩频率越高,计算所得到的噪声极限越大.说明随着外加刺激的增强,胎儿心率变异性的非线性混沌强度是增大的.但是近似熵方法不能反映相似的结果,宫缩反而使胎儿心率变异性的复杂性降低.     

磁刺激光明穴的脑电响应的脑功能网络构建与分析

经颅磁刺激技术与中医穴位刺激相结合的研究和应用,近年来已经取得一定进展,图论理论在脑科学研究领域中也进行一些探索,这些理论和技术的交叉与结合将为神经磁刺激技术的应用和脑科学的研究开启新的方向。利用互相关方法对磁刺激光明穴和假穴的脑电信号进行了两两通道间的线性时域关联特性分析,得出各通道间脑电数据的相关数量关系,并且以相关矩阵的形式表示,通过阈值大小的设定获取邻接矩阵,分别构建磁刺激光明穴与磁刺激假穴实验状态下脑电信号的脑功能网络图。结果发现,磁刺激光明穴的脑功能连接相比于磁刺激假穴的脑功能连接在枕叶(视觉联络区)、额叶区显著增多。利用基于图论的复杂网络理论,对所构建的脑功能网络特性参数进行参数比较和统计学分析。磁刺激光明穴使得脑功能网络发生变化,主要包括网络平均度增大、聚类系数增大、特征路径长度减小、全局效率和局部效率提高、小世界属性增强,并且这些差异经过统计学检验在均值差值上都有量化体现,通过统计检验发现磁刺激光明穴引起的脑功能网络参数的改变具有显著性差异(P<0.05)。研究提示,磁刺激光明穴相比磁刺激假穴,可以提高脑功能网络的全局效率和局部效率,缩短信息传播路径,使各个脑区之间的信息传递更加高效,为磁刺激技术施加于穴位改善神经功能提供一定的理论依据。     

基于心率变异性的精神疲劳的研究

以心率变异性指标对精神疲劳程度进行客观评估。对主动疲劳与被动疲劳进行区分,指出负荷、应激与疲劳之间的联系。在此基础上,设计读书和笔算两种精神疲劳实验。比较读书阶段和音乐放松阶段的心率变异性(HRV)指标,将笔算过程的HRV指标和工效指标结合起来进行分析。结果表明:以工作绩效检测精神疲劳有局限性;读书阶段的疲劳累积效应强于笔算过程引发的疲劳;随着读书或笔算过程中疲劳程度的增加,HRV增加而HR降低,说明精神疲劳促使应激能力降低。HRV直接反映的是应激水平,在严格的约束条件下,HRV可以反映被动疲劳程度;随着被动疲劳程度的增加,通常HRV升高,HR降低,这可能是生理抑制性保护作用。     

磁刺激神门穴脑电信号诱发电位分析及源定位

背景:磁刺激技术是一种新型生物刺激技术,鉴于其使用方便且无痛无创,所以可以采用磁刺激技术刺激穴位替代针刺或电刺穴位。脑电信号可以反映大脑皮质神经的兴奋状态,所以磁刺激与神经相关的神门穴并测量与分析其脑电信号可以研究磁刺激穴位的作用与效果。目的:以不同频率磁刺激刺激肢体神门穴,观察在4种不同状态下脑电信号的诱发电位及其偶极子源定位。方法:选择健康右利手男性6名,女性4名,年龄20～30岁,既往无神经、精神系统病史,实验期间被试保持闭眼静息。用3,1,0.5Hz3种不同频率的磁刺激刺激被试右手神门穴。每种频率的刺激实验分4组,第1组为静息实验,第2组为磁刺激实验,第3组为假刺激实验,第4组为假穴实验。观察4种状态下诱发电位的幅值与潜伏期,诱发电位偶极子源定位冠状面、矢状面和轴状面图。结果与结论:0.5,1Hz磁刺激实验4组状态的脑电信号均无明显诱发电位。3Hz磁刺激安静状态与假刺激状态无诱发电位,磁刺激状态主要诱发产生P300成分,体感诱发电位和其他诱发电位得到抑制;假穴状态除产生P300,另外产生明显体感诱发电位和其他诱发电位。对刺激状态和假穴状态的脑电信号进行脑源定位,经过主成分分析确定有两个偶极子源,磁刺激状态偶极子源定位于额颞区,假穴状态偶极子分布较分散。说明采用磁刺激人体神门穴对脑电信号有明显抑制,与进行针刺或电刺激同样具有调节神经功能的作用。     

基于心率变异性的脑力疲劳检测

目的:研究基于心率变异性(HRV)的脑力疲劳状态的发展变化趋势及评测指标。方法:采用睡眠剥夺的方式诱导脑力疲劳,提取受试者在不同时间安静放松状态下的心电信号的HRV指标,并结合主观疲劳程度与注意力网络任务(ANT)结果研究脑力疲劳的发展变化趋势和评测指标。结果:随着睡眠剥夺时长的增加,受试者的主观疲劳程度逐渐加重,ANT的正确率下降且平均反应时间显著增加,但心率与HRV指标受昼夜节律影响呈现出与主观疲劳程度和ANT结果不同的变化趋势;人体处于脑力疲劳状态时心率下降,HRV指标显著上升。结论:在考虑昼夜节律的情况下,综合心率、HRV指标与ANT结果等多维度信息,可能对昼夜节律规律人群由睡眠剥夺引起的脑力疲劳状态实现更有效的评测。     

低体温与心率变异性和血压变异性的关系

目的: 研究低体温与自主神经功能变化的关系。方法: 采用体表物理降温法逐步降低直肠温度,直肠温度变化范围为19-37 ℃。分别记录不同直肠温度下大鼠动态心电和血压信号。应用心率变异性和血压变异性分析系统评价低体温对心率变异性和收缩压变异性的影响。结果: 心率变异分析表明，直肠温度下降到29 ℃以下,R-R间期均延长（P<0.01）,提示心率明显降低;当直肠温度下降到19-21 ℃时,心率变异归一化低频功率降低（P<0.05）和归一化高频功率增加（P<0.05），而且自主神经的平衡向心迷走神经张力增强的方向发生了转移（P<0.05）。血压变异性分析表明，体温下降到31℃时与呼吸有关的归一化高频功率开始增加（P<0.01）；直肠温度下降到29 ℃以下(除27 ℃外),与呼吸有关的归一化高频功率增加（P<0.05或P<0.01），同时自主神经的平衡也发生了改变（P<0.05）。结论： 随着体温的降低，心血管迷走神经活性增加，自主神经的平衡向迷走神经张力增强的方向转移。低体温对血压变异性的影响敏感于心率变异性。     

Time-Frequency Analysis of Heart Rate Variability During Transient Segments

The spectral characteristics of heart rate variability (HRV) are related to the modulation of the autonomic nervous system. As the physiological condition is changed by such external stimuli such as drugs, postural changes, and anesthesia, or by internal deregulation such as in syncope, adjective autonomic responses could alter HRV characteristics. Time-frequency analysis is commonly used to investigate the time-related HRV characteristics. An alteration of the autonomic regulation resulting in a change in mean heart rate induces a transient component in heart rate, which, with any analysis method based on signals from multiple beats, results in the apparent spread of the spectrum of frequencies. This obscures the spectral components related to the autonomic function. In this paper we investigated the influence of the transient component in several time-frequency methods including the short-time Fourier transform, the Choi-Williams distribution, the smoothed pseudo Wigner–Ville distribution (SPWVD), the filtering SPWVD compensation, and the discrete wavelet transform. One simulated signal and two heart rate signals during general anesthesia and postural change were used for this assessment. The result demonstrates that the filtering SPWVD compensation and the discrete wavelet transform have small spectrum interference from the transient component. © 2001 Biomedical Engineering Society. PAC01: 8719Hh, 8780-y     

基于遥测技术的大鼠24小时心率变异性分析

本研究应用遥测技术连续记录大鼠在无束缚条件下24h心电信号，并通过心率变异性（Heart rate variability，HRV）频谱分析的方法研究大鼠24h自主神经活动。大鼠24hHRV分析结果表明：自主神经活动具有明显昼夜节律，在睡眠期迷走神经活动较活跃，而在清醒期以交感神经活动为主；HRV频谱中低频和高频成分的比值（LF／HF）随着睡眠深度的变化而波动。24hHRV分析可以获得自主神经系统活动的丰富信息，并有助于研究自主神经系统在生理和病理过程中的调控作用。     

温度对心率和心率变异的影响

心率变异（heart rate variability,HRV）是判断自主神经活动最好的定量指标,有时域、频域和非线性等研究方法.频域方法适用于短时程记录,而时域法对分析长时程记录较为理想.HRV的发生基础是自主神经对心率的调节作用,反映了神经体液因素与窦房结相互作用的平衡关系.心率变异受诸多外周和中枢因素的影响,体温及环境温度的变化影响着心血管活动的调节,是HRV的重要起因.极低频（very low frequencies,VLF）功率受温度刺激（如低体温和体温调节活动）的调制,皮肤降温不会特异的影响此频带,表明功率谱中特别频带的改变依赖于体温调节激发模式,而不是体温调节本身.中枢神经系统的损伤可引起心脏自主神经的异常活动并降低HRV,低体温处理可以使HRV的降低更显著.因此研究体温及环境温度与HRV的关系具有非常重要的实用价值.     

Radial basis function neural networks for the characterization of heart rate variability dynamics

This study introduces new neural network based methods for the assessment of the dynamics of the heart rate variability (HRV) signal. The heart rate regulation is assessed as a dynamical system operating in chaotic regimes. Radial-basis function (RBF) networks are applied as a tool for learning and predicting the HRV dynamics. HRV signals are analyzed from normal subjects before and after pharmacological autonomic nervous system (ANS) blockade and from diabetic patients with dysfunctional ANS. The heart rate of normal subjects presents notable predictability. The prediction error is minimized, in fewer degrees of freedom, in the case of diabetic patients. However, for the case of pharmacological ANS blockade, although correlation dimension approaches indicate significant reduction in complexity, the RBF networks fail to reconstruct adequately the underlying dynamics. The transient attributes of the HRV dynamics under the pharmacological disturbance is elucidated as the explanation for the prediction inability.     

Reduced sympathetic responsiveness as well as plasma and tissue noradrenaline concentration in growth hormone transgenic mice

AIMS: Acromegaly [overproduction of growth hormone (GH)] and GH deficiency have both been associated with alterations in autonomic nervous system function. The aim of this study was to investigate autonomic nervous system influence on heart rate (HR) in transgenic mice overexpressing bovine GH (bGH). METHODS: HR and HR variability (HRV) were measured in conscious young (8-13 weeks) and old (5-6 months) female bGH and control mice using telemetry. HR control was studied using antagonists and an agonist of adrenergic and muscarinic receptors. Noradrenaline was measured in plasma, heart and kidney using high performance liquid chromatography. RESULTS: Average 24 h resting HR did not differ between bGH and control mice. After saline injection and after muscarinic blockade with methylscopolamine HR increase was blunted (in old) or absent (in young) bGH mice compared with control mice (P < 0.05). Phenylephrine caused a baroreflex mediated decrease in HR from around 550 to 300-350 beats min(-1), not different between bGH and control mice. Time- and frequency-domain measures of HRV were reduced in old bGH compared with control mice (P < 0.05). Noradrenaline concentrations were reduced by 25-49% in plasma and tissue of bGH compared with control mice (P < 0.05). CONCLUSION: The current study suggests reduced autonomic modulation of HR in bGH transgenic mice. Thus, GH appears to have marked effects on autonomic tone, reducing sympathetic nervous system function possibly via reduced noradrenaline stores.     

Heart rate variability in diabetic patients during orthostatic load — A spectral analytic approach

Summary Spectral analysis of heart rate variability (HRV) was used to assess the autonomic nervous control of cardiac function during orthostatic load in insulin-dependent diabetic patients and healthy subjects. The diabetic patients were divided into three groups: diabetics without neuropathy (group 1), diabetics with peripheral neuropathy (group 2), and diabetics with peripheral and autonomic neuropathy (group 3). Resting mid-frequency (MF, 0.05–0.15 Hz) and respiration-related (RF, power around respiration rate) HRV were significantly lower in group 2 and 3 diabetics than in controls, indicating a reduced parasympathetic nervous system influence on the heart. Standing MF and RF spectral power data were significantly lower in all diabetic groups than in controls, suggesting marked alterations in the autonomic cardiovascular control during a mild physical load not only in symptomatic diabetics but also in patients with no signs and symptoms of neuropathy. The difference between supine and standing MF power, an estimate of-adrenergic influence on the heart, was significantly lower in all diabetic subject groups studied than in controls. This suggests a reduced sympathetic nervous system influence on the heart in diabetic patients. Our data suggest that computerized spectral analysis of HRV during orthostatic load seems to be a very sensitive method of evaluating of the autonomie nervous systems influence on the heart in patients suffering from diabetes niellitus.Abbreviations dB decibel - HRV heart rate variability - LF low-frequency component - MF mid-frequency component - RF respiration related frequency component     

亚健康人群心率变异性特点的研究

目的 探讨亚健康状态人群自主神经功能的特点.方法 随机选取70例亚健康状态人员,75例健康状态人员分别接受短时(5分钟)心率变异性分析,以正常心动周期的标准差(SDNN)、总功率(TP)、低频功率(LF)、高频功率(HF)、低频功率与高频功率比值(LF/HF)为考察指标,记录并进行统计学分析.结果 亚健康状态人群正常心动周期的标准差和总功率都显著低于健康人群(t=-4.643,P=0.00;t=-3.492,P=0.002);同时与健康人群比较,亚健康状态人群的低频功率增高,但未达统计学意义(t=0.898,P=0.377);高频功率有所下降,亦未达到统计学水平(t=-0.899,P=0.376);亚健康状态人群的低频功率与高频功率比值(LF/HF)与健康人群没有差异(t=0.943,P=0.354).结论 亚健康状态人群心率变异性降低,自主神经系统功能减退.     

Effect of reflexological stimulation on heart rate variability

Analysis of heart rate variation (HRV) has become a popular non-invasive tool for assessing the activities of the autonomic nervous system (ANS). HRV analysis is based on the concept that fast fluctuations may specifically reflect changes of sympathetic and vagal activity. It shows that the structure generating the signal is not simply linear, but also involves non-linear contributions. These signals are essentially non-stationary and may contain indicators of cardiac health. This work is an attempt made to do a quantitative study on the effect of reflexology on the heart rate variability (HRV) during reflexologic stimulation. The non-linear parameters are evaluated for this study and the results obtained for 20 subjects are tabulated.     

Autonomic nervous function and localization of cerebral activity during lavender aromatic immersion.

Changes in the autonomic nervous activity can be induced by various sensory and emotional stimuli. The authors examined whether the power spectral analysis of heart rate variability (HRV) could detect changes in autonomic tone following a lavender aroma treatment or not. Healthy young women (n=10, 23+/-3 years old) underwent continuous electrocardiographic (ECG) monitoring before and after (10, 20, 30 minutes) the lavender fragrance stimuli. HRV was expressed by three indices: low (0.04-0.15 Hz) and high (0.15-0.40 Hz) frequency components (nLF and nHF, respectively) as well as LF/HF ratio. Increases in the parasympathetic tone were observed after the lavender fragrance stimulus as seen as increases in the HF component and decreases in the LF/HF. Additional measurement with positron emission tomography (PET) demonstrated the regional metabolic activation in the orbitofrontal, posterior cingulate gyrus, brainstem, thalamus and cerebellum, as well as the reductions in the pre/post-central gyrus and frontal eye field. These results suggested that lavender aromatic treatment induced not only relaxation but also increased arousal level in these subjects.