Effects of performance feedback on cardiovascular reactivity and frontal EEG asymmetry

The process of goal-setting may be captured by psychophysiological variables, such as cardiovascular reactivity (representative of effort mobilisation) and frontal EEG asymmetry (motivational disposition). The current study exposed 32 participants to false performance feedback in order to manipulate goal-setting and mental effort investment. Participants performed five consecutive blocks of the n-back task and received false performance feedback. One group received repeated positive feedback (i.e. performance steadily improved over the five blocks) whilst a second group were exposed to repeated negative feedback (i.e. performance deterioration over five blocks). Blood pressure, power in the mid-frequency and high-frequency component of Heart Rate Variability (HRV), heart rate, frontal EEG asymmetry and subjective self-assessment data were collected. Sustained and repeated positive feedback led to increased systolic blood pressure reactivity and a suppression of the 0.1 Hz component of HRV. Increased relative left hemisphere activation was observed at F3/F4 and FC1/FC2 over successive task blocks in the presence of feedback regardless of positive or negative direction. It is argued that upward goal adjustment accounted for the psychophysiological changes observed in the positive feedback condition.     

Changes in alpha rhythm asymmetry during learning of verbal and visuospatial tasks.

Alpha activity in the two cortical hemispheres was examined during learning and overlearning of a verbal and a visuospatial task. Compared to a pretask baseline condition, the amount of alpha activity during the tasks was decreased. An increase in alpha activity was found from learning to overlearning in both tasks. A greater amount of alpha was found in the right hemisphere for both tasks. In addition, no difference in the degree of alpha asymmetry was found between the tasks. This was discussed in light of prior contrary findings. A significant positive correlation was found between change in learning rate and change in alpha asymmetry during the verbal task. An interpretation of this finding was offered in terms of the level of hemispheric activation reflecting the degree of task engagement.     

Creativity and cortical activation during creative, intellectual and EEG feedback tasks.

Thirty-two male subjects were divided into four groups based on their performance on the remote associates test and alternate uses test, two measures of creativity. Right EEG alpha presence was monitored under basal conditions, while subjects took tests of creativity and intelligence, and while they attempted to enhance and suppress the amount of alpha in a feedback situation. High scorers on the alternate uses test operated at a high percentage of basal alpha during all tests while high scorers on the remote associates test showed differential amounts of alpha presence across tests, with the highest percentage of basal alpha during tests of creativity and the lowest percentage during an intellectual test. Both high creative groups tended to show increases in amount of alpha across trials when trying to suppress alpha as well as when trying to enhance it, but did not differ in overall control from the low creative groups.     

Dysfunctional hemispheric asymmetry of theta and beta EEG activity during linguistic tasks in developmental dyslexia

The phonological deficit hypothesis of dyslexia was studied by analyzing language-related lateralization of theta (4-8 Hz) and beta rhythms (13-30 Hz) during various phases of word processing in a sample of 14 dyslexics and 28 controls. Using a word-pair paradigm, the same words were contrasted in three different tasks: Phonological, Semantic and Orthographic. Compared with controls, dyslexic children showed a delay in behavioral responses which was paralleled by sustained theta EEG peak activity. In addition, controls showed greater theta and beta activation at left frontal sites specifically during the Phonological task, whereas dyslexics showed a dysfunctional pattern, as they were right-lateralized at these sites in all tasks. At posterior locations, and reversed with respect to controls' EEG responses, dyslexics showed greater left lateralization during both Phonological and Orthographic tasks--a result which, in these children, indicates an altered and difficult phonological transcoding process during verbal working memory phases of word processing. Results point to a deficit, in phonological dyslexia, in recruitment of left hemisphere structures for encoding and integrating the phonological components of words, and suggest that the fundamental hierarchy within the linguistic network is disrupted.     

不同思维作业电信号的高准确度模式分类

本文采用独立分量(ICA)分析对不同思维作业的脑电(EEG)信号进行预处理,再用自回归(AR)参数模型提取EEG信号特征,最后利用BP网络完成对特征样本集的训练和分类.实验结果表明,所采用的方法提高了脑电思维模式作业的准确度,对两种到五种不同思维作业未经训练的数据的平均分类准确度达到79%以上,超过现有文献报道的结果.     

EEG alpha power and alpha power asymmetry in sleep and wakefulness.

Asymmetry of waking electroencephalography (EEG) alpha power in frontal regions has been correlated with waking emotional reactivity and the emotional content of dream reports. Little is known regarding alpha asymmetry during sleep. The present study was performed to compare alpha power and alpha power asymmetry in various brain regions across states of sleep and wakefulness. Waking and sleep EEG were recorded in a group of patients undergoing polysomnographic evaluation for possible sleep disorders. Alpha EEG asymmetry in frontal and temporal regions was significantly correlated in waking versus sleep, particularly during rapid eye movement (REM) sleep. These results suggest that patterns of frontal alpha asymmetry are stable across sleep and waking and may be related to emotional reactivity during dreaming. During sleep, alpha power was highest during slow-wave sleep and lowest during REM sleep. Implications of these data for understanding the functional significance of alpha power during waking and sleeping are considered.     

Effects of mental tasks on the cardiorespiratory synchronization

The cardiovascular and respiratory systems are functionally related to each other, but it is unclear if the cerebral cortex can affect their interaction. The effect of a mental task on the synchronization between cardiovascular and respiratory systems was investigated in the article. Electroencephalogram (EEG), electrocardiogram (ECG) and respiratory signal (RES) were collected from 29 healthy male subjects during the mental arithmetic (MA) task and the synchrogram was used to estimate the strength of cardiorespiratory synchronization. Our results showed that MA task significantly increased the breath rate, the heart rate and the EEG power spectral energy in theta band at FC3, FC4 and C4 electrodes (p < 0.01), decreased the duration of cardiorespiratory synchronization epochs (p < 0.05). Moreover the duration of cardiorespiratory synchronization epochs during MA task was negatively correlated with the EEG power spectral energy in theta band at FC3, FC4 and C4 electrodes and the sympathetic activity (p < 0.05). The results demonstrated that ANS and cerebral cortex are implicated in the changes of cardiorespiratory synchronization during MA task.     

脑电反馈控制系统的研制

本文介绍了基于IBM PC/XT计算机的新型双闭环脑电反馈控制系统的研制及在系统中抑制噪声干扰、使系统具有临床实用性的具体措施。该系统将脑电生物反馈和物理刺激的反馈控制加以结合,能有效地进行脑电反馈控制,并具备多种脑电指标的CRT显示和打印机输出。     

A comparison of nomothetic and individualized alpha frequency approaches to measuring frontal EEG alpha asymmetry

Frontal alpha asymmetry (FAA) is considered to be a reliable marker of affective processing and psychopathology. Traditionally, the magnitude of alpha is calculated by taking the average over a nomothetic fixed frequency window (e.g., 8 to 13 Hz). Alternatively, methods have been proposed to extract individualized alpha frequency (IAF) peaks and windows in hopes of improving the reliability and validity of signal detection. However, no study has compared the nomothetic to IAF approaches to examine the reliability and validity of resting FAA in a large well-characterized data set. In this study, we assessed the psychometric performance of the standard fixed window approach, a PZ-alpha based IAF approach and a global-alpha based IAF windows detection approach on a previously collected EEG data set (8 recordings per subject collected on four occasions across two weeks). Our results revealed that resting FAA calculated with these three different methods are highly correlated at all frontal regions (mean r = .98). The stability across the 8 recordings over the two weeks also showed no substantial difference between approaches as indicated by intraclass correlations. Moreover, internal-consistency reliability, validity with respect to measures of emotion and emotion-related psychopathology and state–trait Structure equation model (SEM) fitting were evaluated and yielded no significant differences across methods. Our results supported the overall reliability and validity of two different IAF approaches to assessing resting FAA but fail to find any incremental advantage over nomothetic approaches to defining alpha bands. Guidelines for methods selection for future research are provided.     

The specificity of intrahemispheric EEG alpha coherence asymmetry related to psychological task

Male right handed subjects performed two parallel verbal and nonverbal memory tasks, known to be associated with the anterior temporal lobe, while EEG was recorded from temporal sites referred to either FZ or to linked mastoids. Intrahemispheric coherence and power in the alpha band were calculated. Coherence effects were observed, independent of reference site, which associated the right hemisphere and nonverbal tasks with increased coherence. These effects appear to be relatively specific to more anterior temporal electrode pairs, and confirm previous findings. Power effects demonstrated the difficulty of assessing task-dependent changes independent of reference site, and suggested that specific alpha enhancement may be observed with task involvement. The contribution of coherence analysis to the study of cerebral organisation is discussed.     

Effect of evaluative observation during mental tasks on cardiovascular responses

The effect of evaluative observation on cardiovascular responses was assessed in 20 female undergraduate students. All participants performed a mental arithmetic (MA) task, and a mirror drawing (MD) task, with or without evaluative observation. Heart rate, blood pressure (BP), admittance plethysmography, and task performance were recorded for each task. Both tasks increased blood pressure, but the hemodynamic response patterns were distinct. The MA task induced enhanced cardiac response, whereas the MD task induced a vascular dominant response. Evaluative observation substantially increased BP during both tasks, but it always enhanced cardiac output and reduced total peripheral resistance. The hemodynamic responses changed significantly from vascular dominant to cardiac dominant, particularly during the MD task. The similarity of responses during evaluative and competitive situations is discussed. The significance of interpersonal factors in psychophysiological studies is emphasized.     

Topographical changes in the ongoing EEG related to the difficulty of mental tasks

Summary An experiment was carried out to investigate the hypothesis that task difficulty is reflected in changes in the topographical distribution of the ongoing EEG. Subjects had to perform three different tasks at two difficulty levels each; the Sternberg memory scanning task in an auditory and in a visual mode and a task whose performance required mainly visual scanning. Task difficulty was verified by the measurement of response times. Using a commercial Brain Electrical Activity Mapping device, EEG was recorded from 19 scalp electrodes while the subjects performed the tasks. Spectral matrices of the EEG were calculated to investigate spatial relationships in the EEG. Compared to the lower level, higher task difficulty resulted in EEG changes that led to the identification of two factors. One was the reduction of parietal and occipital alpha activity due to the amount of visual scanning and the other an increase of theta activity in the left frontal electrodes which may be associated with the amount of general mental processing.This work was done while one of the authors (A.G.) held a National Research Council-AFSC Research Associateship. This research was also supported by a grant from the Air Force Office of Scientific Research.     

EEG changes during the performance of verbal and non-verbal tasks

EEGs were recorded from 12 positions of the scalp (10-20 system) in 30 normal right-handed subjects. Powers of alpha component obtained from contralateral loci during their performance of verbal tasks (definition of nouns, tongue twisting) and non-verbal tasks (memorization of shapes, imagination of a face) were compared. At the frontal and occipital regions, the right hemisphere dominance of the alpha component was more distinctly demonstrated during the verbal tasks than the non-verbal tasks, while at the occipito-temporal region, the left hemisphere dominance was distinctly demonstrated during the non-verbal tasks than the verbal tasks. However, the alpha components were dominant at the left occipito-temporal region during the verbal tasks and at the right frontal and occipital regions during the non-verbal tasks. The latter result was discussed in relation to the findings of Moss, Davidson, & Saron (1985) and noise generated by apparatuses. Component analysis was carried out for a correlation matrix made by four task variables and 12 samples of electrode positions. Two factors were derived; the first factor was loaded on the verbal tasks whereas the second factor on non-verbal tasks. The factor scores of the first factor were high at the right temporal region and those of the second factor at the left temporal region. These results proved the utility of principal factor method onto general patterns of alpha component during the tasks.     

EEG alpha oscillations during the performance of verbal creativity tasks: differential effects of sex and verbal intelligence.

Task-related power changes in the EEG alpha band were analyzed in 31 participants (17 males and 14 females) during performance of two verbal creativity tasks. Participants were confronted with verbal problems that are in need of explanation (insight problems) and utopian situations that will actually never happen. In both tasks they were instructed to generate as many but also as unusual, unique or original ideas as possible. To assess brain responses that come along with highly original ideas, individual responses were divided into more and less original ideas (within each participant). Creative problem solving was generally accompanied by lower levels of cortical arousal (i.e., increases in alpha power from a pre-stimulus reference to an activation interval). Additionally, more original (vs. less original) responses were associated with a stronger task-related alpha synchronization in posterior (particularly centroparietal) cortices. Task-related alpha power changes during creative problem solving were also moderated by verbal IQ and sex.     

Interhemispheric asymmetry of EEG alpha activity at rest and during the Wisconsin Card Sorting Test: relations with performance

There are conflicting results regarding the functional asymmetry of the prefrontal cortex. Spectral power analysis of electroencephalographic (EEG) activity can provide important clues about the cortical mechanisms. In this study, interhemispheric EEG alpha power asymmetry of healthy individuals was investigated during the execution of the Wisconsin Card Sorting Test (WCST) and during rest. We analyzed alpha-1 (8.6-10.2 Hz) and alpha-2 (10.9-12.5 Hz) bands separately and found some evidence to indicate that lower and upper alpha bands reflect different cortical processes. On the other hand, greater alpha power during resting correlated with higher performance on the WCST. The lower left frontal alpha power during WCST correlated significantly with the higher WCST performance. However, greater bilateral parietal alpha power during WCST correlated with higher performance. Significant correlations between EEG activity and WCST performance were, in general, restricted to lower alpha power, both at rest and during the task. These findings are discussed with regard to attention processes reflected by lower alpha activity.     

Acute cortisol administration modulates EEG alpha asymmetry in volunteers: relevance to depression

The acute effects of cortisol (35mg) administration in 11 healthy male volunteers on resting frontal EEG asymmetry measured in the alpha band were investigated, using a within-subjects double-blind design. Results were indicative of a relative increase of right frontal activity with cortisol. This pattern of activity is similar to the deviant pattern that has been reported in patients suffering from depression, a condition often accompanied by elevated plasma cortisol levels. The significant effect on frontal asymmetry provides convergent support for our hypothesis, based upon previous results, that sustained (>30 minutes after stress termination) relative high levels of cortisol inhibit approach motivation.     

Interhemispheric EEG asymmetry in patients with insomnia during nocturnal sleep

Sleep EEG was recorded and analyzed in patients with neurotic insomnia. It was found that interhemispheric asymmetry in the same individual can vary during sleep from right-hemispheric to left-hemispheric. Interhemispheric EEG asymmetry is closely related to the stage of sleep. The development of left-hemisphere or right-hemisphere asymmetry is mainly determined by activity of the right hemisphere. The development of interhemispheric asymmetry during wakefulness, stages 1 and 2 sleep, and delta sleep is mediated by common mechanisms. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 141, No. 2, pp. 157–160, February, 2006