Processing of emotional adjectives: Evidence from startle EMG and ERPs

Time course of attentional bias in anxiety: emotion and gender specificity

Anxiety is characterized by cognitive biases, including attentional bias to emotional (especially threatening) stimuli. Accounts differ on the time course of attention to threat, but the literature generally confounds emotional valence and arousal and overlooks gender effects, both addressed in the present study. Nonpatients high in self-reported anxious apprehension, anxious arousal, or neither completed an emotion-word Stroop task during event-related potential (ERP) recording. Hypotheses differentiated time course of preferential attention to emotional stimuli. Individuals high in anxious apprehension and anxious arousal showed distinct early ERP evidence of preferential processing of emotionally arousing stimuli along with some evidence for gender differences in processing. Healthy controls showed gender differences at both early and later processing stages. The conjunction of valence, arousal, and gender is critical in the time course of attentional bias.

Emotion modulates language production during covert picture naming

Previous studies have shown that emotional content modulates the activity of several components of the event-related potentials during word comprehension. However, little is known about the impact of affective information on the different processing stages involved in word production. In the present study we aimed to investigate the influence of positive and negative emotions in phonological encoding, a process that have been shown to take place between 300 and 450 ms in previous studies. Participants performed letter searching in a picture naming task. It was found that grapheme monitoring in positive and negative picture names was associated with slower reaction times and enhanced amplitudes of a positive component around 400 ms as compared to monitoring letters in neutral picture names. We propose that this modulation reflects a disruption in phonological encoding processes as a consequence of the capture of attention by affective content. Grapheme monitoring in positive picture names also elicited higher amplitudes than letter searching in neutral image names in a positive component around 100 ms. This amplitude enhancement might be interpreted as a manifestation of the 'positive offset' during conceptual preparation processes. The results of a control experiment with a passive viewing task showed that both effects cannot be simply attributed to the processing of the emotional images per se. Overall, it seems that emotion modulates word production at several processing stages.

Looking at emotional words is not the same as reading emotional words: Behavioral and neural correlates

Recent research suggests that the allocation of attentional resources to emotional content during word processing might be sensitive to task requirements. This question was investigated in two tasks with similar instructions. The stimuli were positive, negative, and neutral nouns. Participants had to identify meaningful words embedded in a stream of non-recognizable stimuli (task 1) or pseudowords (task 2). Task 1 could be successfully performed on the basis of the perceptual features whereas a lexico-semantic analysis was required in task 2. Effects were found only in task 2. Positive nouns were identified faster, with fewer errors and elicited larger amplitude in an early negativity. Also, the amplitude of a late positivity was larger for both positive and negative nouns than for neutral nouns. It is concluded that some degree of linguistic processing is needed to direct attention to the affective content during word processing.

Traces of fear in the neural web--magnetoencephalographic responding to arousing pictorial stimuli

The concept of a 'fear network', i.e. an interconnected set of neural representations has been instrumental in explaining symptoms and their maintenance in anxiety disorders. The neural representations include both, response propositions such as flight or freezing and chunks of memory, conceptualized as Hebbian cell assemblies. Consequently, the fear network undergoes neuroplastic modifications, for instance, incremental enlargements with repeated exposure to threat and danger. This will in turn modify future processing of sensory stimuli and ultimately lead to an altered architecture of the brain's processing machinery and information processing modes. Using repeated exposure to traumatic stress as a model to study these processes, we summarize a series of magnetoencephalographic investigations from our laboratory, which demonstrate a characteristic pattern of early activation (before 100 ms latency to the eliciting stimulus) in fronto-cortical circuits by high-arousing, aversive pictorial and verbal stimuli in individuals presenting with posttraumatic stress disorder (PTSD). We propose that this pattern reflects a preference of stressed brains to engage a 'low road' sensory processing, which is fast but uncoupled from prefrontal regulatory control and which easily activates an alarm response, whereas less emphasis is given the more careful and contextual processing via the 'high road' along the ventral stream. As a result, the brain's architecture is changed from a careful analyzer of the environment to a rapid threat detector with a low threshold to engage in costly defense.

ERP Evidence for Rapid Hedonic Evaluation of Logos

We know that human neurocognitive systems rapidly and implicitly evaluate emotionally charged stimuli. But what about more everyday, frequently encountered kinds of objects, such as computer desktop icons and business logos? Do we rapidly and implicitly evaluate these more prosaic visual images, attitude objects that might only engender a mild sense of liking or disliking, if at all? To address this question, we asked participants to view a set of unfamiliar commercial logos in the context of a target identification task as brain electrical responses to these objects were recorded via event-related potentials (ERPs). Following this task, participants individually identified those logos that were most liked or disliked, allowing us to then compare how ERP responses to logos varied as a function of hedonic evaluation—a procedure decoupling evaluative responses from any normative classification of the logos themselves. In Experiment 1, we found that visuocortical processing manifest a specific bias for disliked logos that emerged within the first 200 msec of stimulus onset. In Experiment 2, we replicated this effect while dissociating normative- and novelty-related influences. Taken together, our results provide direct electrophysiological evidence suggesting that we rapidly and implicitly evaluate commercial branding images at a hedonic level.

Neurophysiological correlates of comprehending emotional meaning in context

Although the neurocognitive mechanisms of nonaffective language comprehension have been studied extensively, relatively less is known about how the emotional meaning of language is processed. In this study, electrophysiological responses to affectively positive, negative, and neutral words, presented within nonconstraining, neutral contexts, were evaluated under conditions of explicit evaluation of emotional content (Experiment 1) and passive reading (Experiment 2). In both experiments, a widely distributed Late Positivity was found to be larger to negative than to positive words (a "negativity bias"). In addition, in Experiment 2, a small, posterior N400 effect to negative and positive (relative to neutral) words was detected, with no differences found between N400 magnitudes to negative and positive words. Taken together, these results suggest that comprehending the emotional meaning of words following a neutral context requires an initial semantic analysis that is relatively more engaged for emotional than for nonemotional words, whereas a later, more extended, attention-modulated process distinguishes the specific emotional valence (positive vs. negative) of words. Thus, emotional processing networks within the brain appear to exert a continuous influence, evident at several stages, on the construction of the emotional meaning of language.

Emotional facilitation effect in the picture-word interference task: an ERP study

In this paper, we aimed to verify the emotional facilitation effect in the picture-word interference task using event-related potentials. Twenty-one healthy subjects were asked to categorize the emotional valences of pictures accompanied by emotionally congruent, either centrally or laterally positioned Chinese words. For both the foveal and lateral word presentations, the reaction times were faster compared to the picture-only presentation. Compared to the picture-only presentation, P200 amplitude increased under the foveal word presentation condition and decreased under the lateral word presentation condition, indicating that more attentional resources were required when an accompanying word was in the center of a picture than when the word was in the lateral position. Latency of P300 was shorter in response to picture-word stimuli irrespective of word position, indicating that an emotionally congruent word facilitated the emotional processing of the target picture, which verified the emotional facilitation effect and was consistent with the results in psychology. The late positive component was more positive when the picture-word stimuli were more positive, which reflected the feature of positivity offset. The findings suggest that the time window for an emotional facilitation effect may be limited to processing aspects associated with P300 (i.e., affective evaluation).

Influence of aggression on information processing in the emotional stroop task--an event-related potential study

Aggression is a common behavior which has frequently been explained as involving changes in higher level information processing patterns. Although researchers have started only recently to investigate information processing in healthy individuals while engaged in aggressive behavior, the impact of aggression on information processing beyond an aggressive encounter remains unclear. In an event-related potential study, we investigated the processing of facial expressions (happy, angry, fearful, and neutral) in an emotional Stroop task after experimentally provoking aggressive behavior in healthy participants. Compared to a non-provoked group, these individuals showed increased early (P2) and late (P3) positive amplitudes for all facial expressions. For the P2 amplitude, the effect of provocation was greatest for threat-related expressions. Beyond this, a bias for emotional expressions, i.e., slower reaction times to all emotional expressions, was found in provoked participants with a high level of trait anger. These results indicate significant effects of aggression on information processing, which last beyond the aggressive encounter even in healthy participants.

Overlapping neural correlates of reading emotionally positive and negative adjectives

Comparison of positive and negative naturally read adjectives to neutral adjectives yielded an overlapping higher BOLD response in the occipital and the orbitofrontal cortex (gyrus rectus). Superior medial frontal gyrus and posterior cingulate gyrus showed higher BOLD response to negative adjectives and inferior frontal gyrus to positive adjectives. The overlap of activated regions and lack of pronounced distinct regions supports the assumption that the processing of negative and positive words mainly takes place in overlapping brain regions.

Amygdala activation during reading of emotional adjectives--an advantage for pleasant content

This event-related functional magnetic resonance imaging (fMRI) study investigated brain activity elicited by emotional adjectives during silent reading without specific processing instructions. Fifteen healthy volunteers were asked to read a set of randomly presented high-arousing emotional (pleasant and unpleasant) and low-arousing neutral adjectives. Silent reading of emotional in contrast to neutral adjectives evoked enhanced activations in visual, limbic and prefrontal brain regions. In particular, reading pleasant adjectives produced a more robust activation pattern in the left amygdala and the left extrastriate visual cortex than did reading unpleasant or neutral adjectives. Moreover, extrastriate visual cortex and amygdala activity were significantly correlated during reading of pleasant adjectives. Furthermore, pleasant adjectives were better remembered than unpleasant and neutral adjectives in a surprise free recall test conducted after scanning. Thus, visual processing was biased towards pleasant words and involved the amygdala, underscoring recent theoretical views of a general role of the human amygdala in relevance detection for both pleasant and unpleasant stimuli. Results indicate preferential processing of pleasant information in healthy young adults and can be accounted for within the framework of appraisal theory.

The cognitive consequences of emotion regulation: an ERP investigation

Increasing evidence suggests that emotion regulation (ER) strategies modulate encoding of information presented during regulation; however, no studies have assessed the impact of cognitive reappraisal ER strategies on the processing of stimuli presented after the ER period. Participants in the present study regulated emotions to unpleasant pictures and then judged whether a word was negative or neutral. Electromyographic measures (corrugator supercilli) confirmed that individuals increased and decreased negative affect according to ER condition. Event-related potential analyses revealed smallest N400 amplitudes to negative and neutral words presented after decreasing unpleasant emotions and smallest P300 amplitudes to words presented after increasing unpleasant emotions whereas reaction time data failed to show ER modulations. Results are discussed in the context of the developing ER literature, as well as theories of emotional incongruity (N400) and resource allocation (P300).

Facial attractiveness modulates early and late event-related brain potentials

Facial attractiveness is of high importance for human interaction and communication, and everyday experience suggests that the mere aspect of a face elicits spontaneous appraisal of attractiveness. However, little is known about the time course of brain responses related to this process. In the present study, event-related brain potentials were recorded during attractiveness classification of facial portraits that were standardized with respect to facial expression. The faces were either preceded by another face of high or low attractiveness or by an affectively neutral object. Attractive as opposed to non-attractive target faces elicited an early posterior negativity (EPN; approximately 250 ms) and a late parietal positivity (LPC; 400-600 ms), which were not modulated by affectively congruent prime faces. Elevated LPC activity had previously been shown in response to attractive versus non-attractive faces, possibly reflecting task-related evaluative processes. An enhanced EPN had been reported for faces with emotional compared to neutral emotional expression, and related to facilitated selection of emotional information. Extending these findings, our study is the first to report an attractiveness-related ERP modulation prior to the LPC, suggesting that appraising facial attractiveness starts already at processing stages associated with stimulus selection.

Does emotion modulate the blink reflex in human conditioning? Startle potentiation during pleasant and unpleasant cues in the picture?picture paradigm

Emotional processes modulate the size of the eyeblink startle reflex in a picture-viewing paradigm, but it is unclear whether emotional processes are responsible for blink modulation in human conditioning. Experiment 1 involved an aversive differential conditioning phase followed by an extinction phase in which acoustic startle probes were presented during CS+, CS-, and intertrial intervals. Valence ratings and affective priming showed the CS+ was unpleasant postacquisition. Blink startle magnitude was larger during CS+ than during CS-. Experiment 2 used the same design in two groups trained with pleasant or unpleasant pictorial USs. Ratings and affective priming indicated that the CS+ had become pleasant or unpleasant in the respective group. Regardless of CS valence, blink startle was larger during CS+ than CS- in both groups. Thus, startle was not modulated by CS valence.

Low spatial frequency filtering modulates early brain processing of affective complex pictures

Recent research on affective processing has suggested that low spatial frequency information of fearful faces provide rapid emotional cues to the amygdala, whereas high spatial frequencies convey fine-grained information to the fusiform gyrus, regardless of emotional expression. In the present experiment, we examined the effects of low (LSF, <15 cycles/image width) and high spatial frequency filtering (HSF, >25 cycles/image width) on brain processing of complex pictures depicting pleasant, unpleasant, and neutral scenes. Event-related potentials (ERP), percentage of recognized stimuli and response times were recorded in 19 healthy volunteers. Behavioral results indicated faster reaction times in response to unpleasant LSF than to unpleasant HSF pictures. Unpleasant LSF pictures and pleasant unfiltered pictures also elicited significant enhancements of P1 amplitudes at occipital electrodes as compared to neutral LSF and unfiltered pictures, respectively; whereas no significant effects of affective modulation were found for HSF pictures. Moreover, mean ERP amplitudes in the time between 200 and 500ms post-stimulus were significantly greater for affective (pleasant and unpleasant) than for neutral unfiltered pictures; whereas no significant affective modulation was found for HSF or LSF pictures at those latencies. The fact that affective LSF pictures elicited an enhancement of brain responses at early, but not at later latencies, suggests the existence of a rapid and preattentive neural mechanism for the processing of motivationally relevant stimuli, which could be driven by LSF cues. Our findings confirm thus previous results showing differences on brain processing of affective LSF and HSF faces, and extend these results to more complex and social affective pictures.

Neuroimaging methods in affective neuroscience: selected methodological issues

A current goal of affective neuroscience is to reveal the relationship between emotion and dynamic brain activity in specific neural circuits. In humans, noninvasive neuroimaging measures are of primary interest in this endeavor. However, methodological issues, unique to each neuroimaging method, have important implications for the design of studies, interpretation of findings, and comparison across studies. With regard to event-related brain potentials, we discuss the need for dense sensor arrays to achieve reference-independent characterization of field potentials and improved estimate of cortical brain sources. Furthermore, limitations and caveats regarding sparse sensor sampling are discussed. With regard to event-related magnetic field (ERF) recordings, we outline a method to achieve magnetoencephalography (MEG) sensor standardization, which improves effects' sizes in typical neuroscientific investigations, avoids the finding of ghost effects, and facilitates comparison of MEG waveforms across studies. Focusing on functional magnetic resonance imaging (fMRI), we question the unjustified application of proportional global signal scaling in emotion research, which can greatly distort statistical findings in key structures implicated in emotional processing and possibly contributing to conflicting results in affective neuroscience fMRI studies, in particular with respect to limbic and paralimbic structures. Finally, a distributed EEG/MEG source analysis with statistical parametric mapping is outlined providing a common software platform for hemodynamic and electromagnetic neuroimaging measures. Taken together, to achieve consistent and replicable patterns of the relationship between emotion and neuroimaging measures, methodological aspects associated with the various neuroimaging techniques may be of similar importance as the definition of emotional cues and task context used to study emotion.

Emotional and semantic networks in visual word processing: insights from ERP studies

The event-related brain potential (ERP) literature concerning the impact of emotional content on visual word processing is reviewed and related to general knowledge on semantics in word processing: emotional connotation can enhance cortical responses at all stages of visual word processing following the assembly of visual word form (up to 200 ms), such as semantic access (around 200 ms), allocation of attentional resources (around 300 ms), contextual analysis (around 400 ms), and sustained processing and memory encoding (around 500 ms). Even earlier effects have occasionally been reported with subliminal or perceptual threshold presentation, particularly in clinical populations. Here, the underlying mechanisms are likely to diverge from the ones operational in standard natural reading. The variability in timing of the effects can be accounted for by dynamically changing lexical representations that can be activated as required by the subjects' motivational state, the task at hand, and additional contextual factors. Throughout, subcortical structures such as the amygdala are likely to contribute these enhancements. Further research will establish whether or when emotional arousal, valence, or additional emotional properties drive the observed effects and how experimental factors interact with these. Meticulous control of other word properties known to affect ERPs in visual word processing, such as word class, length, frequency, and concreteness and the use of more standardized EEG procedures is vital. Mapping the interplay between cortical and subcortical mechanisms that give rise to amplified cortical responses to emotional words will be of highest priority for future research.

Event-related potential studies of language and emotion: words, phrases, and task effects

This chapter reviews research that focuses on the effects of emotionality of single words, and of simple phrases, on event-related brain potentials when these are presented visually in various tasks. In these studies, presentation of emotionally evocative language material has consistently elicited a late (c. 300-600 ms post-onset) positive-going, largely frontal-central shift in the event-related potentials (ERPs), relative to neutral materials. Overall, affectively pleasant and unpleasant words or phrases are quite similar in their neuroelectric profiles and rarely differ substantively. This emotionality effect is enhanced in both amplitude and latency when emotional content is task relevant, but is also reliably observed when the task involves other semantically engaging tasks. On the other hand, it can be attenuated or eliminated when the task does not involve semantic evaluation (e.g., lexical decisions to words or orthographic judgments to the spelling patterns) or when comprehension of phrases requires integration of the connotative meaning of several words (e.g., compare dead puppy and dead tyrant). Taken together, these studies suggest that the emotionality of written language has a rapid and robust impact on ERPs, which can be modulated by specific task demands as well as the linguistic context in which the affective stimulus occurs.