Effect of Problem Solving on Right and Left Hemisphere 40 Hertz EEG Activity

EEG activity within the alpha, beta II and 40 Hz bands was monitored during periods of problem solving and non-problem solving. Concomitant 40 Hz EMG activity was also monitored to show a dissociation between it and 40 Hz EEG activity. Twenty-four right-handed subjects were used. Results indicate that during problem solving there is a reduction in activity within the alpha and beta II bands relative to non-problem solving periods. Within the 40 Hz EEG band there was increased activity over the hemisphere assumed to be maximally engaged in the problem solving task. Activity within the 40 Hz EMG band showed bilateral increases during problem solving. It was also found that 40 Hz EMG activity made little, if any, contribution to 40 Hz EEG activity.     

Task Dependent Cerebral Lateralization of the 40 Hertz EEG Rhythm

Task dependent lateralization of the 40 Hz EEG rhythm and its relationship to 40 Hz EMG activity were investigated in 24 right-handed subjects. Each subject was administered four tests: verbal analogies, mathematical problems, facial discrimination, and geometric figure rotation. Bilateral EEG and EMG activity were recorded during each of the tests. Lateralization of the 40 Hz EEG rhythm was found during three of the four tasks. No comparable lateralization of 40 Hz EMG activity was found. Results are discussed in terms of 40 Hz EEG as resulting from a focused state of cortical arousal, and of 40 Hz EEG as differentiable from 40 Hz EMG.     

Multiple Response Comparison of Parietal EEG and Frontalis EMG Biofeedback

In Study I parietal EEG and frontalis EMG were simultaneously recorded from 20 normal subjects while half of the subjects received 45 min of eyes-closed alpha EEG enhancement feedback and the other half received a similar amount of EMG suppression feedback. EMG feedback resulted in a significant reduction in frontalis EMG activity accompanied by a reliable increase in parietal alpha density, while EEG feedback produced only an increase in alpha without corresponding EMG reduction. In Study II, each of 8 subjects underwent four separate feedback contingencies in two 40-min sessions—one session with eyes open and the other with eyes closed. The four types of feedback were: a) alpha-up (alpha enhancement), b) alpha-down (alpha suppression), c) EMG-down (frontalis tension decrease), and d) EMG-up (frontalis tension increase). EMG feedback, up and down, resulted in the more consistent pattern of generalized arousal changes reflected in heart rate and respiratory rate as well as EEG and EMG activity. Within the constraints of a limited training period, the results suggest that frontalis EMG feedback is the more efficient procedure for producing a generalized relaxation response. However, since fingertip vasoconstriction accompanied all four types of feedback, caution must be exercised to avoid the oversimplification of generalized organism effects.     

基于脑肌电融合的混合脑机接口研究

动作模式识别是脑机接口技术的核心内容之一。针对目前脑机接口动作识别模式单一、识别率低等问题,基于混合脑机接口思想,提出一种脑电和肌电特征融合策略,可实现单侧肢体不同动作模式的有效分类,进而可用于脑机接口技术。同步采集9名健康受试者单侧手腕屈/伸两种动作模式下的脑电信号和表面肌电信号,分别提取脑电信号事件相关去同步化特征和表面肌电信号的积分肌电值特征,构建基于支持向量机和粒子群优化算法的脑肌电融合及运动模式识别模型,通过调整“特征融合系数”来实现动作模式最优分类,从而提高模式识别的准确率;进一步通过递降健康人的肌电信号幅值来模拟患者和运动疲劳状态下的肌电信号,验证所提出方法对动作模式识别的有效性。实验结果表明,基于脑肌电融合特征的动作模式识别率(98%)比单纯依靠脑电特征的识别率(73%)提高25%;在运动疲劳状态下,基于脑肌电融合特征的识别率稳定在80%以上,比单纯依靠肌电特征的识别率提高14%。可见,脑肌电融合策略能提高动作模式识别的准确性和鲁棒性,为混合脑机接口技术提供条件。     

Comparative Study on Fractal Dimension Property of 40Hz Event Related Potentials Under Various Cognitive Tasks Loading Conditions

INTRODUCTION　　The application of fractal and chaotic theory to brain research and analysis hasbecome a very popular field.Modern research indicates that EEG signalsare noton-ly quasi-periodic orstochastic one,butalso presentchaotic characteristic under …     

A Multiple-Response Evaluation of EMG Biofeedback Performance During Training and Stress-Induction Conditions

The present study evaluated multiple system physiological responding which accompanied EMG biofeedback performance under two conditions—during EMG biofeedback training sessions, and during the utilization of that training in the presence of a stressor. Twelve subjects were randomly assigned to one of two groups: 1) an EMG biofeedback group, or 2) a false-EMG biofeedback group. During the training sessions, significant frontalis EMG decreases were produced by the biofeedback group. This performance was associated with a concomitant decrease in heart rate and respiration rate, but an increase in skin conductance level. The biofeedback group was also able to maintain a low level of EMG activity during a stress-induction procedure. However, this low level of activity did not generalize to other physiological responses. Heart rate and skin conductance levels both increased, which coincided with the subjects' self-report of anxiety during this phase of the study. These data clearly demonstrate that single-system arousal reduction produced by EMG biofeedback training, rather than producing cross-system arousal reduction, produces specificity of a single response change under a stress-inducing situation.     

Functional imaging of Brain responses to repetitive sensory stimulation: Sources estimated from EEG and SPECT

Summary This study examined the effect of modality of stimulation on two measures of cerebral function: (a) the scalp distribution of sensory evoked potentials and (b) the cerebral distribution of radiolabelled HMPAO. Steady-state stimulation in the auditory, somatosensory or visual modality was presented to six subjects. Scalp potentials were measured from a distribution of electrodes, and the radiopharmaceutical was injected through an indwelling intravenous catheter midway through the stimulation/ recording session. Equivalent dipole sources estimated from the spatial distribution of the scalp potentials were found to be consistent with regions of high HMPAO uptake as imaged by Single Photon Emission Computed Tomography (SPECT).This study was supported by grants from: Department of Defense Ministry of Transport, Ministry of Supply and Services, and the Natural Sciences and Engineering Research Council.     

Topographic distribution of the 40 Hz auditory evoked-Related potential in normal and aged subjects

Summary Galambos, Makeig and Talmachoff (1981) described what they called the 40 Hz event-related potential (ERP). This steady-state response is an EEG following response to repetitive auditory stimulation which becomes sinusoidal in form and maximal in amplitude at rates between 35 and 45 Hz. The present study was designed to examine the scalp topography of the 40 Hz ERP in order to complement previous magnetoencephalographic studies which implicate auditory cortex in the generation of the response. In addition, this study was designed to collect normative data on an aged sample in order to assess the effects of aging on the response. 40 Hz ERP's were recorded from a group of seven audiometrically and neurologically normal elderly subjects (mean age = 69.6 years) and a younger group of five normal adults (mean age = 38.0 years), using 1000 Hz tones presented binaurally at 40 per second. A 21 channel recording system was used to obtain a comprehensive picture of the scalp distribution of the response. Recorded ERP's were Fourier transformed to enhance the signal-to-noise ratio. No significant differences were found in phase or amplitude of the 40 Hz ERP between the two age groups, indicating that the normal aging process does not have an effect on this response. Topographic maps of the 40 Hz ERP showed reversals of electrode potential in temporal regions, supporting an interpretation of bilateral sources in temporal cortex. The data presented in this study complement previous studies of the 40 Hz event-related magnetic field and support the position that temporal cortex is involved in the generation of the response.This study was funded in part by N.S.E.R.C., D.O.D. and the Gerontology Research Centre, Simon Fraser University.