ERP evidence for a sex-specific Stroop effect in emotional speech

The present study investigated the interaction of emotional prosody and word valence during emotional comprehension in men and women. In a prosody-word interference task, participants listened to positive, neutral, and negative words that were spoken with a happy, neutral, and angry prosody. Participants were asked to rate word valence while ignoring emotional prosody, or vice versa. Congruent stimuli were responded faster and more accurately as compared to incongruent emotional stimuli. This behavioral effect was more salient for the word valence task than for the prosodic task and was comparable between men and women. The event-related potentials (ERPs) revealed a smaller N400 amplitude for congruent as compared to emotionally incongruent stimuli. This ERP effect, however, was significant only for the word valence judgment and only for female listeners. The present data suggest that the word valence judgment was more difficult and more easily influenced by task-irrelevant emotional information than the prosodic task in both men and women. Furthermore, although emotional prosody and word valence may have a similar influence on an emotional judgment in both sexes, ERPs indicate sex differences in the underlying processing. Women, but not men, show an interaction between prosody and word valence during a semantic processing stage.     

Functional connectivity between the amygdala and prefrontal cortex in medication-naive individuals with major depressive disorder

Background

Convergent evidence suggests dysfunction within the prefrontal cortex (PFC) and amygdala, important components of a neural system that subserves emotional processing, in individuals with major depressive disorder (MDD). Abnormalities in this system in the left hemisphere and during processing of negative emotional stimuli are especially implicated. In this study, we used functional magnetic resonance imaging (fMRI) to investigate amygdala–PFC functional connectivity during emotional face processing in medication-naive individuals with MDD.

Methods

Individuals with MDD and healthy controls underwent fMRI scanning while processing 3 types of emotional face stimuli. We compared the strength of functional connectivity from the amygdala between the MDD and control groups.

Results

Our study included 28 individuals with MDD and 30 controls. Decreased amygdala–left rostral PFC (rPFC) functional connectivity was observed in the MDD group compared with controls for the fear condition (p < 0.05, corrected). No significant differences were found in amygdala connectivity to any cerebral regions between the MDD and control groups for the happy or neutral conditions.

Limitations

All participants with MDD were experiencing acute episodes, therefore the findings could not be generalized to the entire MDD population.

Conclusion

Medication-naive individuals with MDD showed decreased amygdala–left rPFC functional connectivity in response to negative emotional stimuli, suggesting that abnormalities in amygdala–left rPFC neural circuitry responses to negative emotional stimuli might play an important role in the pathophysiology of MDD.     

The impact of verbal framing on brain activity evoked by emotional images

Emotional stimuli generally command more brain processing resources than non-emotional stimuli, but the magnitude of this effect is subject to voluntary control. Cognitive reappraisal represents one type of emotion regulation that can be voluntarily employed to modulate responses to emotional stimuli. Here, the late positive potential (LPP), a specific event-related brain potential (ERP) component, was measured in response to neutral, positive and negative images while participants performed an evaluative categorization task. One experimental group adopted a "negative frame" in which images were categorized as negative or not. The other adopted a "positive frame" in which the exact same images were categorized as positive or not. Behavioral performance confirmed compliance with random group assignment, and peak LPP amplitude to negative images was affected by group membership: brain responses to negative images were significantly reduced in the "positive frame" group. This suggests that adopting a more positive appraisal frame can modulate brain activity elicited by negative stimuli in the environment.     

Electrophysiological correlates of semantic processing during encoding of neutral and emotional pictures in patients with ADHD

The current study investigated the relevance of semantic processing and stimulus salience for memory performance in young ADHD patients and healthy control participants. 18 male ADHD patients and 15 healthy control children and adolescents participated in an ERP study during a visual memory paradigm with two different encoding tasks requiring either perceptual or semantic processing of neutral and emotional pictures. ADHD patients and healthy controls both showed a more negative slow-wave in response to task cues signalling semantic as compared to perceptual stimulus processing. In contrast to ADHD patients, healthy control children showed a larger increase in memory performance for deeply processed neutral pictures which was accompanied by a more positive mid-latency ERP component (so-called P300) after stimulus onset. Our results demonstrate that ADHD patients succeeded in allocating neural resources in preparation of different task demands. However, this increase in preparatory activation to the semantic task cue did not suffice to support successful processing and encoding of neutral stimuli to the same extent as in healthy controls. These findings provide evidence that ADHD patients show deficits in translating pre-stimulus mobilization of neural resources to successful memory formation in the absence of salient stimulus material.     

Variation in the corticotropin-releasing hormone receptor 1 (CRHR1) gene influences fMRI signal responses during emotional stimulus processing

The corticotropin-releasing hormone (CRH) system coordinates neuroendocrine and behavioral responses to stress and has been implicated in the development of major depressive disorder (MDD). Recent reports suggest that GG-homozygous individuals of a single nucleotide polymorphism (rs110402) in the CRH receptor 1 (CRHR1) gene show behavioral and neuroendocrine evidence of stress vulnerability. The present study explores whether those observations extend to the neuronal processing of emotional stimuli in humans. CRHR1 was genotyped in 83 controls and a preliminary sample of 16 unmedicated patients with MDD who completed a functional magnetic resonance imaging scan while viewing blocks of positive, negative, and neutral words. In addition, potential mediating factors such as early life stress, sex, personality traits, and negative memory bias were examined. Robust differences in blood oxygenation level-dependent (BOLD) signal were found in healthy controls (A allele carriers > GG-homozygotes) in the right middle temporal/angular gyrus while subjects were viewing negative versus neutral words. Among GG-homozygotes, BOLD signal in the subgenual cingulate was greater in MDD participants (n = 9) compared with controls (n = 33). Conversely, among A-carriers, BOLD signal was smaller in MDD (n = 7) compared with controls (n = 50) in the hypothalamus, bilateral amygdala, and left nucleus accumbens. Early life stress, personality traits, and levels of negative memory bias were associated with brain activity depending on genotype. Results from healthy controls and a preliminary sample of MDD participants show that CRHR1 single nucleotide polymorphism rs110402 moderates neural responses to emotional stimuli, suggesting a potential mechanism of vulnerability for the development of MDD.     

抑郁症患者汉语情绪词阈下的Stroop效应事件相关电位

背景：抑郁症患者负性认知偏差与情绪信息加工的关系是一个重要的研究课题。情绪Stroop测验常用于评估情绪加工特点,而情绪词阈下Stroop刺激模式也常用于精神病学临床研究。 目的：本研究采用阈下汉语情绪词Stroop刺激范式来探讨抑郁症患者异常情绪信息加工的事件相关电位(ERP)效应。 设计,时间和地点：随机对照设计,时间为2007年8月至2008年3月,地点在中南大学湘雅二医院。 研究对象：首发抑郁症患者26例,符合DSM-IV抑郁症诊断标准,无脑部疾病、躯体疾病,未进行电休克治疗和抗抑郁药物治疗。健康对照组24例。两组在年龄、性别和教育水平方面无差异,均为右利手。 方法：采用阈下汉语情绪词Stroop刺激范式,要求被试对呈现200ms的红色或蓝色方块进行反应,而汉语情绪词阈下启动刺激为20ms。主要分析行为学和ERP数据。 主要测试指标：反应时和ERP成分的潜伏期和波幅。参照ERP平均波幅图以及其它研究,主要分析N270 (220~300ms)成分和N400 (380~450ms)成分的潜伏期和波幅。 结果：行为数据显示两组正确率之间无显著性差异,抑郁症组反应时比正常对照组延长,尤其是负性词与中性词(p<0.01)。重复测量方差分析表明,N270成分的波幅有词性和电极的主效应(p<0.01)以及词性和电极的交互效应(p<0.05);两组波幅大小顺序均为正性词>负性词>中性词。组别、词性差异波地形图显示差异主要分布在额区和左侧顶颞区。N400成分的波幅有词性和电极的主效应(p<0.01),潜伏期显示电极的主效应(p<0.01)以及电极和组别的交互效应(p<0.01);两组波幅大小顺序均为正性词>负性词>中性词,而且两组之间的三种情绪词波幅之间有显著性差异(p<0.01)。组别、词性差异波地形图显示差异主要分布在左右额区、中央区和左侧顶颞区。 结论：抑郁症患者执行阈下汉语情绪词Stroop刺激作业时表现了异常的情绪信息加工特征,以及对汉语情绪词三种词性进行语义激活时与正常组相比表现为不同的ERP时程效应。研究结果支持我们提出的正负性情绪平行神经模型。     

More excited for negative facial expressions in depression: Evidence from an event-related potential study

Objective

This study aims to investigate the intensity evaluation of social stimuli in depression.

Methods

Twenty-four never-disordered control participants (NC), 24 sub-clinically depressed individuals and 24 participants diagnosed with a current major depressive disorder (MDD) were recruited. All participants completed an emotional intensity evaluation task, in which they were required to judge the intensity of the facial expressions by pressing response keys, with the event-related potential (ERP) being recorded during the process.

Results

The MDD participants had higher intensity scores for sad faces compared with the NC group, longer reaction times (RTs) for all faces compared with other groups and higher P1 and P2 amplitude for sad faces compared with other faces. The sub-clinically depressed individuals had lower intensity scores for happy and neutral faces compared with other groups, longer RTs for happy faces compared with other faces and higher P1 and P2 amplitudes for happy faces compared with sad faces.

Conclusion

The findings suggest that the MDD participants are more excited for negative facial expressions, while the sub-clinically depressed individuals might have a disturbed perception for happy stimuli, which suggests a different cognitive pattern for facial expressions between MDD and sub-clinical depression. Moreover, the deep perception for sad faces is correlated with increased suicidal ideation.

Significance

The intensity effect of social stimuli (facial expressions) was observed in sub-clinically and clinically depressed (MDD) individuals simultaneously, which might suggest that the more excited perception for negative facial expressions is a stable cognitive vulnerability possibly associated with the occurrence or recurrence of depression.     

Differential effects of emotional content on event-related potentials in word recognition memory

The aim of this study was to delineate the influence of the emotional content of stimuli to be remembered on the recognition performance of normal subjects by means of the event-related potential (ERP) technique. When words are presented repeatedly, brain responses to repeated and recognized items are characterized by a more positive waveform, referred to as "old/new effect". Words judged for their emotional connotation ("negative", "positive" and "neutral") were presented successively on a video monitor to subjects, who had the task to indicate whether a given word occurred for the first ("new") or second ("old") time within the list by pressing one of two buttons. For each word category, the ERPs of the old words were more positive compared to those of the new items from about 250 ms after stimulus. The old/new effect was significantly enhanced for the negative and positive items compared to the neutral stimuli between 450 and 650 ms after stimulus pointing to a significant influence of the emotional content of words on verbal memory processes. This paradigm appears to be feasible to investigate interactions of emotion and cognition in psychiatric patients.     

Implicit and explicit memory processes in panic patients as reflected in behavioral and electrophysiological measures

Implicit and explicit memory processes for panic-relevant and neutral word stimuli were examined in 16 panic patients and 16 healthy participants matched for sex, age, and education, using behavioral and electrophysiological measures. In the study phase, panic-relevant and neutral words were presented and the level of processing was varied by requiring either shallow (orthographic) or deeper (syntactic) processing. Implicit memory was tested with a lexical decision task, explicit memory with a recognition task. Panic patients and healthy participants did not differ in behavioral (response time) or event-related brain potential (ERP) measures of implicit memory. However, panic patients deviated from healthy participants in the recognition test, an explicit memory test. Although recognition of panic words was overall worse compared to neutral words, panic patients compared to healthy participants exhibited enhanced discrimination scores and faster reaction times for panic words. The level of processing manipulation had comparable effects on patients and healthy participants. While neither behavioral nor electrophysiological measures provided evidence for an implicit memory bias in panic patients, behavioral measures confirmed an explicit memory bias in panic patients for panic-relevant stimuli.     

Tracing the time course of emotion perception: the impact of stimulus physics and semantics on gesture processing

Numerous event-related brain potential (ERP) studies reveal the differential processing of emotional and neutral stimuli. Yet, it is an ongoing debate to what extent the ERP components found in previous research are sensitive to physical stimulus characteristics or emotional meaning. This study manipulated emotional meaning and stimulus orientation to disentangle the impact of stimulus physics and semantics on emotional stimulus processing. Negative communicative hand gestures of Insult were contrasted with neutral control gestures of Allusion to manipulate emotional meaning. An elementary physical manipulation of visual processing was implemented by presenting these stimuli vertically and horizontally. The results showed dissociable effects of stimulus meaning and orientation on the sequence of ERP components. Effects of orientation were pronounced in the P1 and N170 time frames and attenuated during later stages. Emotional meaning affected the P1, evincing a distinct topography to orientation effects. Although the N170 was not modulated by emotional meaning, the early posterior negativity and late positive potential components replicated previous findings with larger potentials elicited by the Insult gestures. These data suggest that the brain processes different attributes of an emotional picture in parallel and that a coarse semantic appreciation may already occur during relatively early stages of emotion perception.