Evoked Synchronization/Desynchronization of Cortical Electrical Activity in Response to Facial Stimuli during Formation of a Set to an Emotionally Negative Expression

Evoked EEG theta and alpha rhythm synchronization/desynchronization responses to facial stimuli were studied in healthy subjects (n = 35) in an experiment involving formation of a set to an emotionally negative facial expression. The magnitude of the evoked theta activity synchronization response in the group of subjects with the plastic type of set was greater and the latent period was shorter than in the group with the rigid type of set. These differences were particularly clear in the temporal and parietal-occipital areas. A sufficiently high level of the phasic theta potentials synchronization response, reflecting the level of activity of the corticohippocampal feedback system during the perception of facial stimuli, was required for rapid substitution of the set to facial expressions. In subjects with plastic sets, the evoked low-frequency alpha potentials response was apparent as synchronization, while that in subjects of the “rigid” group consisted of desynchronization. These results were interpreted in terms of the concept of Klimesch (2007) that the evoked alpha potentials synchronization response is a measure of inhibition in cognitive activity. The alpha potentials synchronization response reflects the process of inhibitory control, which plays an important coordinating role in organizing the plastic properties of the set in relation to its inhibition when it ceases to correspond to new stimuli. The involvement of the tonic and phasic forms of cortical activation, mediated by the corticohippocampal and frontothalamic brain systems, in the functional organization of the cognitive set to an emotionally negative facial expression is discussed.     

Synchronization of EEG Theta and Alpha Rhythms in an Unconscious Set to the Perception of an Emotional Facial Expression

Coherence functions in cortical electrical potentials in the theta (4–7 Hz) and alpha ranges (8–13 Hz) recorded during the formation and testing stages of a visual set to facial images bearing an emotional expression (an angry face) were studied in healthy adult subjects (n = 35). Differences in the spatial synchronization between theta and alpha potentials were seen, especially in rigid forms of the set, in which cases of erroneous perception of facial expressions were seen with contrast and assimilative illusions. This group of subjects (n = 23) showed increases in theta potentials between the dorsolateral areas of the frontal cortex (the orbitofrontal cortex) and the temporal area in the right hemisphere. A mechanism is proposed for the development of visual illusions. Analysis of the coherence functions of cortical potentials in the theta and alpha ranges generates a “window” which can be used to study the operation of the two functional systems integrating brain activity, i.e., the corticohippocampal and frontothalamic, in the perception of a facial expression. The frontothalamic system is associated with more diffuse types of cortical activation, especially in its anterior areas. The theta rhythm system evidently facilitates integration of the frontal cortex with the temporal area in the right hemisphere and the connections of the latter with the parietal and central zones in both hemispheres.     

Analysis of Evoked Electrical Activity in the Cerebral Cortex Using Wavelet Transformation at Different Stages of a Set to an Emotional Facial Expression

A set to an emotionally negative facial expression was developed in 35 healthy subjects. Wavelet transformation coefficients were used to study the rhythmic components of evoked EEG activity in the alpha and theta ranges at different stages of the set. Individual differences in the perception of facial expressions on activation of the set allowed the subjects to be divided into two groups: those with rapid (plastic sets) and those with prolonged extinction of its effects (rigid sets). At the set formation stage, subjects with rigid sets showed higher maximum coefficient values in the alpha rhythm than subjects with plastic sets. That EEG responses of subjects with plastic sets showed higher mean coefficients in the theta rhythm than subjects with rigid sets. Groups of subjects were characterized by different maximum and mean wavelet transformation coefficients, depending on the stage of the experiment. It is suggested that sets to an emotional facial expression were accompanied by different ratios of cortical-subcortical interactions both in different groups of subjects and at different stages of the experiment.     

The Role of the Context of Cognitive Activity in the Recognition of Facial Emotional Expressions

The effects of the types of additional cognitive tasks (visuospatial or semantic) added to the context of experiments with a set to recognition of an emotionally negative facial expression were studied in healthy human subjects. Loading on working memory decreased the plasticity of the set: changes in the situation increased the number of erroneous recognitions of the facial expression. Differences were seen in the nature of erroneous recognitions (assimilative and contrast illusions) depending on the additional task. Analysis of coherence functions of cortical electrical potentials in the low-frequency alpha (8–10 Hz) and beta (14–20 Hz) ranges supported the hypothesis that increases in the loading on working memory lead to decreases in the involvement of the frontal mechanisms of selective attention in the formation and actualization of the set. This leads to slowing of the process of set shifting. Loading on working memory induced hemisphere asymmetry in prestimulus electrical activity: spatial synchronization of theta potentials significantly decreased in the right hemisphere and increased in the left. The functional significance of coherence connections in the theta range between the dorsolateral part of the prefrontal cortex and the temporal area in the right hemisphere for the process of set substitution is discussed.     

Pattern Recognition of Self-Reported Emotional State from Multiple-Site Facial EMG Activity During Affective Imagery

A multivariate pattern-classification system was developed for the study of facial electromy-ographic (EMG) patterning in 12 female subjects during affect-laden imagery and for posed facial expressions. A parameter-extraction procedure identified the dynamic EMG signal properties which accorded the maximal degree of self-reported emotion discrimination. Discriminant analyses on trialwise EMG vectors allowed assessment of specific EMG-site conformations typifying rated emotions of happiness, sadness, anger, and fear. The discriminability among emotion-specific EMG conformations was correlated with subjective ratings of affective-imagery vividness and duration. Evidence was obtained suggesting that the EMG patterns encoded complex, “blended” reported affective states during the imagery. Classification analyses produced point-predictions of reported emotional states in 10 of the 12 subjects, and provided the first computer pattern recognition of self-reported emotion from psychophysiological responses.     

面部表情识别的影响因素:面部特征及观察者特性

面部表情识别受到了交流双方的多种因素的影响。本文首先从表情发出者的角度,介绍了面部本身的特性(包括特定部位和整体的特征信息)对面部表情识别的影响;接着从信息接收者的角度,介绍了观察者自身的特性(如所处的情绪状态、内部思维线索、性别、年龄、文化背景等)对面部表情识别的影响;最后,对未来研究中如何改进实验设计、扩展研究问题提出了建议。     

基于ERP情绪状态对工作记忆刷新功能影响研究

近年来,情绪对工作记忆的建设作用正逐步受到关注,尤其是情绪对工作记忆中央执行系统刷新功能的影响至关重要。组织16名青年受试者参与动态工作记忆任务实验,探讨积极、中性和消极三类不同情绪状态对工作记忆刷新功能的影响。实验首先采用国际情绪图片系统(IAPS)使受试者分别进入三类情绪状态,随后执行4个数字的动态工作记忆任务。结果发现,积极情绪状态下工作记忆刷新时间显著增长(积极情绪状态:(1.016±0.338) s;中性情绪状态:(0.814±0.347) s, P<0.05);刷新ERP在额中央部N2幅值显著小于中性情绪;工作记忆刷新的后期(400～1 000 ms),在频带13～30 Hz处的能量降低显著低于中性情绪。消极情绪状态下工作记忆刷新时间与中性情绪无显著差异;工作记忆刷新的早期(0～400ms),在频带0～8Hz处的能量升高显著低于中性情绪。以上结果说明积极情绪对工作记忆刷新存在干扰作用,但未发现消极情绪对工作记忆刷新的显著影响。有关情绪状态影响工作记忆刷新机制的初步研究将为提高工作记忆刷新绩效提供实验依据。     

情绪影响工作记忆的研究现状与发展动向

情绪对知觉、注意、记忆和决策等认知功能起着重要的作用。工作记忆是对信息进行暂时加工和贮存的容量有限记忆系统,在知觉、记忆与人类认知行为之间搭起信息交流的平台。现有研究证明,情绪状态会影响正常人的工作记忆,而情绪障碍性疾病患者的工作记忆易受负性情绪影响而受到损伤,所以情绪与工作记忆的关系,特别是情绪对工作记忆的影响一直是认知心理学、认知神经科学的研究热点。研究情绪如何影响工作记忆,从情绪与工作记忆基本概念入手,分别综述其相关生理机制、经典理论、常用实验范式和已有研究成果,最后讨论其存在问题并预测其发展动向。     

Spatial Synchronization of Cortical Electrical Activity at Different Stages of a Visual Set in 8-Year-Old Children with Different Levels of Development of the Frontothalamic Selective Attention System

Children of early school age (8.0 ± 0.1 years) were separated on the basis of EEG characteristics into the following groups: 1) those with normal development of the frontothalamic selective attention system (n = 21) and 2) those with functional immaturity of the frontothalamic system due to delays in its development (n = 29). The Uznadze paradigm was used to form a set to nonverbal visual stimuli (circles of different sizes). The set was rigid in most group 2 children. The coherence of cortical electrical potentials in the theta, alpha, and beta ranges recorded from the frontal, central, temporal, parietal, and occipital areas was analyzed. Intergroup differences were most marked at the set actualization stage in children with plastic sets: the coherence of potentials between the anterior and posterior zones was significantly more marked in subjects with immature frontothalamic systems than in the “normal” group. The relationship between the level of coherence of potentials with set plasticity was more defined in the “frontothalamic” group than in the control group. Rigid sets were associated with significantly lower levels of coherence of potentials in all ranges as compared with the baseline EEG with the eyes open. The increase in the coherence of theta potentials on set actualization occurring mainly in the right hemisphere in the “frontothalamic” group was interpreted as a measure of the compensatory increase in the role of the corticohippocampal system to support set plasticity.     

The Effect of Prestimulus Alpha Activity on the P300

Trials on which highly discrepant, auditory ‘oddball’ stimuli were presented were sorted into two bins on the basis of prestimulus alpha band RMS magnitude. The trial bins were then separately averaged to produce a ‘high alpha’ auditory ERP (event-related potential) and a ‘low alpha’ ERP for each subject. Study 1 found that larger amplitude P300s were obtained in the ‘high alpha’ ERP. No effect of alpha was found on the N100. Study 2 employed extra factors of stimulus intensity change (increases and decreases) and alpha measurement period (before and after the ‘oddball’ stimulus). It was found that P300 amplitude enhancement was independent of both stimulus intensity and the amount of alpha poststimulus. The data are discussed in terms of cascaded inhibition from the mesencephalic reticular formation to nucleus reticularis of the thalamus to a thalamo-cortical system responsible for the generation of both alpha and the P300.     

词汇背景对面孔情绪识别的影响

目的:考察不同步的词汇背景对面孔情绪识别的影响。方法:以28名健康大学生为被试,采用情绪启动范式,设置五种不同的SOA条件(250 ms、100 ms、0 ms、-100 ms、-250 ms),启动刺激除了情绪词,还采用中性词作为控制条件,要求被试对目标情绪面孔做情绪类型判断。结果:在SOA为100 ms、0 ms和-100 ms时,均出现了词汇背景和面孔的显著的情绪一致性效应;其他两种SOA条件下没有出现该效应。当SOA为100 ms时,词汇背景对面孔情绪识别的影响主要表现为相同情绪价的词汇背景对面孔情绪识别的促进效应;而当SOA为0 ms和-100 ms时,词汇背景的影响主要表现为不同情绪价的词汇背景对面孔情绪识别的阻碍效应。结论:面孔情绪的识别受到了不同步的语言背景的影响,这种影响局限在一定的时间范围内,而且不同时间条件下影响的内在机制不同。     

The Differential Role of Verbal and Spatial Working Memory in the Neural Basis of Arithmetic

We examine the relations of verbal and spatial working memory (WM) ability to the neural bases of arithmetic in school-age children. We independently localize brain regions subserving verbal versus spatial representations. For multiplication, higher verbal WM ability is associated with greater recruitment of the left temporal cortex, identified by the verbal localizer. For multiplication and subtraction, higher spatial WM ability is associated with greater recruitment of right parietal cortex, identified by the spatial localizer. Depending on their WM ability, children engage different neural systems that manipulate different representations to solve arithmetic problems.     

Impairments to the Functions of Spatial Working Memory in Mild Depression and their Neurophysiological Correlates

Neuroscience and Behavioral Physiology - Objectives. To identify the characteristics of impairments to spatial working memory and their neurophysiological correlates in patients with mild...     

Effects of Skilled Training on Sleep Slow Wave Activity and Cortical Gene Expression in the Rat

Study Objective:

The best characterized marker of sleep homeostasis is the amount of slow wave activity (SWA, 0.5–4 Hz) during NREM sleep. SWA increases as a function of previous waking time and declines during sleep, but the underlying mechanisms remain unclear. We have suggested that SWA homeostasis is linked to synaptic potentiation associated with learning during wakefulness. Indeed, studies in rodents and humans found that SWA increases after manipulations that presumably enhance synaptic strength, but the evidence remains indirect. Here we trained rats in skilled reaching, a task known to elicit long-term potentiation in the trained motor cortex, and immediately after learning measured SWA and cortical protein levels of c-fos and Arc, 2 activity-dependent genes involved in motor learning.

Design:

Intracortical local field potential recordings and training on reaching task.

Setting:

Basic sleep research laboratory.

Patients or Participants:

Long Evans adult male rats.

Interventions:

N/A

Measurements and Results:

SWA increased post-training in the trained cortex (the frontal cortex contralateral to the limb used to learn the task), with smaller or no increase in other cortical areas. This increase was reversible within 1 hour, specific to NREM sleep, and positively correlated with changes in performance during the prior training session, suggesting that it reflects plasticity and not just motor activity. Fos and Arc levels were higher in the trained relative to untrained motor cortex immediately after training, but this asymmetry was no longer present after 1 hour of sleep.

Conclusion:

Learning to reach specifically affects gene expression in the trained motor cortex and, in the same area, increases sleep need as measured by a local change in SWA.

Citation:

Hanlon EC; Faraguna U; Vyazovskiy VV; Tononi G; Cirelli C. Effects of skilled training on sleep slow wave activity and cortical gene expression in the rat. SLEEP 2009;32(6):719-729.     

Effects of Working Memory Load on Performance and Cardiovascular Activity in Younger and Older Workers

Background

Working memory (WM) declines with ageing, and this may cause problems in older workers who have to do complex work requiring WM.

Purpose

We tested the assumption that an increase in WM load negatively affects performance and results in impaired cardiovascular adaptation to changing task demands in older workers relative to younger ones.

Method

Thirty-three younger (29?±?3?years) and 32 older (55?±?3?years) workers had to perform a visual 0-back (low WM load) and 2-back (high WM load) task. Heart rate (HR), heart rate variability (HRV), beat-to-beat blood pressure (BP) and baroreflex were registered.

Results

In the high WM load condition, older adults responded more slowly and less accurately than younger adults, while no age effects in the low WM load condition were found. Older workers showed a higher systolic blood pressure (SBP) reactivity to high WM load as well as a diminished post-task recovery of SBP and HRV than younger workers. Factor analysis demonstrated a close relationship between HR, baroreflex and HRV and their modulation by a common factor (??vagal tone??) in the younger group. By contrast, HR was more related to the ??sympathetic?? factor in the older group.

Conclusion

The data suggest that older workers as compared with younger ones are impaired in tasks requiring WM, which is accompanied by enhanced cardiovascular ??costs?? in terms of increased SBP and reduced vagal control over HR.