共查询到8条相似文献,搜索用时 15 毫秒
1.
The characteristics of EEG recorded before, in the course, and after three sequential static grasp efforts developed by the
right hand were analyzed in 14 healthy volunteers of both sexes, 19 to 56 years old. The grasps were 3 min long, and intervals
between the sequential trials were 5 min long. The mean intensity was, as a rule, the greatest in the first trial and decreased,
because of fatigue, in the second and third trials. In the course of the grasp effort, significant (P ≤ 0.05) or close to significant decreases in the spectral power were observed in all trials within the alpha2 subrange in
some frontal, central, and central/temporal leads. This reaction of desynchronization of alpha2 oscillations probably reflects
activation of the sensorimotor cortical zones. Within the above period, the power of alpha2 oscillations increased in the
occipital leads. In a few leads of the frontal group, the powers of delta, theta1, theta2, and alpha1 oscillations increased
significantly (P < 0.05) in the course of the first trial. Such reaction was not observed in the second and third trials, while the powers
of delta and alpha1 ranges increased in the occipital sites (P < 0.05). The powers of delta and theta oscillations increased, as compared with the control values, after the second and
third grasps. Such specific EEG modifications in sequential trials can be related to the actions of a novelty factor in the
first trial and a fatigue factor in the subsequent trials. The coherence coefficient (CC) of alpha and beta oscillations for
symmetric leads usually increased in the course of the grasp. This effect reached a significance level (P < 0.05) for alpha2 oscillations in central, posterotemporal, parietal, and occipital pairs. The CC for beta2 oscillations
increased in both temporal lead pairs. A drop in the interhemisphere coherence was more typical of the delta and theta1 ranges.
Therefore, changes in the CC values show that the structure of interhemisphere interaction undergoes modifications with the
development of the grasp static efforts.
Neirofiziologiya/Neurophysiology, Vol. 37, No. 4, pp. 362–371, July–August, 2005. 相似文献
2.
Effect of cold stimulation of the arm fingers on the spectral/coherent EEG characteristics in humans
V. V. Garkavenko O. P. Man’kovskaya T. G. Omel’chenko A. V. Gorkovenko A. N. Shevko 《Neurophysiology》2008,40(3):228-230
Examination of modifications of EEG in humans induced by cold stimulation of the arm fingers showed that the EEG frequency
composition noticeably depended on this thermal influence (in the relaxed state with no movements or during realization of
voluntary cyclic movements by the fingers of another arm). In the resting state, cold stimulation mostly induced intensification
of the delta activity, while, when coinciding with the performance of voluntary movements, it also resulted in increases in
the powers of oscillations of the alpha1 and beta1 ranges. The structure of changes in the coefficients of coherence under
the influence of cooling also depended on the conditions of testing (in the resting state or during motor activity). Therefore,
the effect of tonic cold stimulation on the interaction between synchronizing and desynchronizing cerebral systems and interrelations
between different cortical zones was modified under conditions of realization of a motor function.
Neirofiziologiya/Neurophysiology, Vol. 40, No. 3, pp. 268–270, May–June, 2008. 相似文献
3.
目的:研究功率谱熵在痫性发作大鼠脑电检测中的应用。方法:采用青霉素在大鼠海马微注射制备急性痫性发作模型,以深部电极记录大鼠原始脑电信号,将24只SD大鼠随机分成四组,即正常组(A),对照组(B),单电极组(C),多电极组(D)。C、D组大鼠经致痫后观察未发作期、发作前期、发作期和发作后期四期脑电信号的变化,运用谱熵对四期脑电信号进行分析,并与A、B组进行对比。结果:C组和D组脑电功率谱熵显示两组发作期与未发作期、发作前期、发作后期比较有显著差异(P0.05),发作期明显低于其它各期;未发作期和发作前期相比有明显差异(P0.05),发作前期较未发作期降低;将D组大鼠海马致痫灶(a)及其同侧附近(b)、对侧(c)三点发作各期脑电功率谱熵进行对比分析,发作前期和发作期a、b、c三点比较有明显差异(P0.05),a点最低,c点的功率谱熵值最高。结论:功率谱熵可以预报痫性发作并可对癫痫病灶的定位提供一定的帮助。 相似文献
4.
In this study the distribution of estimated broad band spectral power is evaluated. Under weak assumptions it is possible to appropriate this distribution by a χ2-distribution and to construct tolerance intervals with great statistical accuracy. The theoretical results implicate a new methodical basis for statistical comparison of spectral parameters in EEG analysis. 相似文献
5.
R.J. Croft S. Leung R.J. McKenzie S.P. Loughran S. Iskra D.L. Hamblin N.R. Cooper 《Bioelectromagnetics》2010,31(6):434-444
The present study was conducted to determine whether adolescents and/or the elderly are more sensitive to mobile phone (MP)‐related bioeffects than young adults, and to determine this for both 2nd generation (2G) GSM, and 3rd generation (3G) W‐CDMA exposures. To test this, resting alpha activity (8–12 Hz band of the electroencephalogram) was assessed because numerous studies have now reported it to be enhanced by MP exposure. Forty‐one 13–15 year olds, forty‐two 19–40 year olds, and twenty 55–70 year olds were tested using a double‐blind crossover design, where each participant received Sham, 2G and 3G exposures, separated by at least 4 days. Alpha activity, during exposure relative to baseline, was recorded and compared between conditions. Consistent with previous research, the young adults' alpha was greater in the 2G compared to Sham condition, however, no effect was seen in the adolescent or the elderly groups, and no effect of 3G exposures was found in any group. The results provide further support for an effect of 2G exposures on resting alpha activity in young adults, but fail to support a similar enhancement in adolescents or the elderly, or in any age group as a function of 3G exposure. Bioelectromagnetics 31:434–444, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
6.
Zhenguo Zhu Guoyong Wu Huajiang Wei Hongqin Yang Yonghong He Shusen Xie Qingliang Zhao Xiao Guo 《Journal of biophotonics》2012,5(7):536-543
The potential of OCT applied for early breast cancer detection attracted significant efforts. The permeability coefficients and the percentages of OCT signal enhancement for normal and cancerous breast tissues have been investigated from the experiments of 20% glucose, 40% glucose, and 20% mannitol in vitro. Obtained results indicate that the permeability coefficient in breast cancer tissue is prominently larger than that in normal breast tissue, while the optical clearing effect is just the reverse to that for each agent. The results suggest that OCT has the ability to distinguish cancer tissue from different aspect. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
《Journal of electromyography and kinesiology》2014,24(4):452-464
The muscle compound action potential (M wave) recorded under monopolar configuration reflects both the propagation of the action potentials along the muscle fibres and their extinction at the tendon. M waves recorded under a bipolar configuration contain less cross talk and noise than monopolar M waves, but they do not contain the entire informative content of the propagating potential. The objective of this study was to compare the effect of changes in muscle fibre conduction velocity (MFCV) on monopolar and bipolar M waves and how this effect depends on the distance between the recording electrodes and tendon. The study was based on a simulation approach and on an experimental investigation of the characteristics of surface M waves evoked in the vastus lateralis during 4-s step-wise isometric contractions in knee extension at 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% MVC. The peak-to-peak duration (Durpp) and median frequency (Fmedian) of the M waves were calculated. For monopolar M waves, changes in Durpp and Fmedian produced by MFCV depended on the distance from the electrode to the tendon, whereas, for bipolar M waves, changes in Durpp and Fmedian were largely independent of the electrode-to-tendon distance. When the distance between the detection point and tendon lay between approximately 15 and 40 mm, changes in Durpp of bipolar M waves were more pronounced than those of distal monopolar M waves but less marked than those of proximal monopolar M waves, and the opposite occurred for Fmedian. Since, for bipolar M waves, changes in duration and power spectral features produced by alterations in MFCV are not influenced by the electrode-to-tendon distance, the bipolar electrode configuration is a preferable choice over monopolar arrangements to estimate changes in conduction velocity. 相似文献
8.
In 80 healthy humans, we studied changes in the frequency spectrum and values of the relative spectral coefficients for subsequent 1-Hz-wide frequency bands under conditions of simultaneous lateralized stimulation of the retinal zones, which form receptive fields for the right- and for the left-brain hemispheres; light of different colors was used for stimulation. We found that reactions of the right and left hemispheres to such stimulations demonstrated obvious specificity; spatial characteristics of these reactions were obtained. Changes in the values of most corresponding spectral coefficients in the hemispheres usually had similar directions and demonstrated similarity in their intensities, which is indicative of a complementary pattern of the interhemispheric interaction. Reciprocal changes in the corresponding spectral coefficients in the hemispheres were observed more rarely. Modifications of EEG upon red-green stimulations of different polarity were found to be similar, which can be a manifestation of the moderating influence of the right hemisphere on the left one. 相似文献