Neural Processing of Repeated Emotional Scenes in Schizophrenia,Schizoaffective Disorder,and Bipolar Disorder

Impaired emotional processing and cognitive functioning are common in schizophrenia, schizoaffective disorder, and bipolar disorders, causing significant socioemotional disability. While a large body of research demonstrates abnormal cognition/emotion interactions in these disorders, previous studies investigating abnormalities in the emotional scene response using event-related potentials (ERPs) have yielded mixed findings, and few studies compare findings across psychiatric diagnoses. The current study investigates the effects of emotion and repetition on ERPs in a large, well-characterized sample of participants with schizophrenia-bipolar syndromes. Two ERP components that are modulated by emotional content and scene repetition, the early posterior negativity (EPN) and late positive potential (LPP), were recorded in healthy controls and participants with schizophrenia, schizoaffective disorder, bipolar disorder with psychosis, and bipolar disorder without psychosis. Effects of emotion and repetition were compared across groups. Results displayed significant but small effects in schizophrenia and schizoaffective disorder, with diminished EPN amplitudes to neutral and novel scenes, reduced LPP amplitudes to emotional scenes, and attenuated effects of scene repetition. Despite significant findings, small effect sizes indicate that emotional scene processing is predominantly intact in these disorders. Multivariate analyses indicate that these mild ERP abnormalities are related to cognition, psychosocial functioning, and psychosis severity. This relationship suggests that impaired cognition, rather than diagnosis or mood disturbance, may underlie disrupted neural scene processing in schizophrenia-bipolar syndromes.     

Implicit emotion regulation affects outcome evaluation

Efficient implicit emotion regulation processes, which run without awareness, are important for human well-being. In this study, to investigate the influence of implicit emotion regulation on psychological and electrophysiological responses to gains and losses, participants were required to select between two Chinese four-character idioms to match the meaning of the third one before they performed a monetary gambling task. According to whether their meanings were related to emotion regulation, the idioms fell into two categories. Event-related potentials and self-rating emotional experiences to outcome feedback were recorded during the task. Priming emotion regulation reduced subjective emotional experience to both gains and losses and the amplitudes of the feedback-related negativity, while the P3 component was not influenced. According to these results, we suggest that the application of implicit emotion regulation effectively modulated the subjective emotional experience and the motivational salience of current outcomes without the cost of cognitive resources. This study implicates the potential significance of implicit emotion regulation in decision-making processes.     

Three stages of emotional word processing: an ERP study with rapid serial visual presentation

Rapid responses to emotional words play a crucial role in social communication. This study employed event-related potentials to examine the time course of neural dynamics involved in emotional word processing. Participants performed a dual-target task in which positive, negative and neutral adjectives were rapidly presented. The early occipital P1 was found larger when elicited by negative words, indicating that the first stage of emotional word processing mainly differentiates between non-threatening and potentially threatening information. The N170 and the early posterior negativity were larger for positive and negative words, reflecting the emotional/non-emotional discrimination stage of word processing. The late positive component not only distinguished emotional words from neutral words, but also differentiated between positive and negative words. This represents the third stage of emotional word processing, the emotion separation. Present results indicated that, similar with the three-stage model of facial expression processing; the neural processing of emotional words can also be divided into three stages. These findings prompt us to believe that the nature of emotion can be analyzed by the brain independent of stimulus type, and that the three-stage scheme may be a common model for emotional information processing in the context of limited attentional resources.     

Stimulus novelty and emotion perception: the near absence of habituation in the visual cortex

In rapid serial visual presentation of pictures, an early event-related brain potential component shows enlarged negativity over occipital regions for emotional pictures compared with neutral pictures. The present study examined whether the processing of emotional target pictures varies as a function of stimulus repetition. Accordingly, pictures of erotica, neutral contents, and mutilations were repeatedly presented (90 times) while the electroencephalogram was recorded with a 129 dense sensor array. As in previous studies, emotional pictures were associated with a larger posterior negativity than neutral pictures. Furthermore, differential emotion processing did not vary as a function of stimulus repetition and was similarly expressed across blocks of picture presentation. These findings suggest the near absence of habituation in differential emotion processing during perceptual processing.     

Attention and emotion: an ERP analysis of facilitated emotional stimulus processing

Recent event-related potential studies observed an early posterior negativity (EPN) reflecting facilitated processing of emotional images. The present study explored if the facilitated processing of emotional pictures is sustained while subjects perform an explicit non-emotional attention task. EEG was recorded from 129 channels while subjects viewed a rapid continuous stream of images containing emotional pictures as well as task-related checkerboard images. As expected, explicit selective attention to target images elicited large P3 waves. Interestingly, emotional stimuli guided stimulus-driven selective encoding as reflected by augmented EPN amplitudes to emotional stimuli, in particular to stimuli of evolutionary significance (erotic contents, mutilations, and threat). These data demonstrate the selective encoding of emotional stimuli while top-down attentional control was directed towards non-emotional target stimuli.     

Slow biasing of processing resources in early visual cortex is preceded by emotional cue extraction in emotion–attention competition

In our previous studies on competition for attentional processing resources in early visual cortex between a foreground task and distracting emotional background images we found that emotional background images withdraw attentional resources from the foreground task after about 400 ms. Costs in behavioral data and a significant reduction of the steady state visual evoked potential (SSVEP) amplitude that was elicited by the foreground task lasted for several hundred milliseconds. We speculated that the differential effect in SSVEP amplitudes is preceded by the extraction of the emotional cue. Event related potential (ERP) studies to emotional and neutral complex images identified an early posterior negativity (EPN) as a robust neural signature of emotional cue extraction. The late positive potential (LPP) was related to in‐depth processing of the emotional image. We extracted ERPs that were evoked by the onset of background images concurrently with the SSVEP that was elicited by the foreground task. Emotional compared to neutral background pictures evoked a more negative EPN at about 190 ms and a more positive LPP at about 700 ms after image onset. SSVEP amplitudes became significantly smaller with emotional background images after about 400 ms lasting for several hundred ms. Interestingly, we found no significant correlations between the three components, indicating that they act independently. Source localizations resulted in nonoverlapping cortical generators. Results suggest a cascade of perceptual processes: Extraction of the emotional cue preceded biasing of attentional resources away from the foreground task towards the emotional image for an evaluation of the picture content. Hum Brain Mapp 35:1477–1490, 2014. © 2013 Wiley Periodicals, Inc.     

Neural correlates of implicit object identification

The present study sought to assess neural correlates of implicit identification of objects by means of fMRI, using tasks that require matching of the physical properties of objects. Behavioural data suggests that there is automatic access to object identity when observers attend to a physical property of the form of an object (e.g. the object's orientation) and no evidence for semantic processing when subjects attend to colour. We evaluated whether, in addition to neural areas associated with decisions to specific perceptual properties, areas associated with access to semantic information were activated when tasks demanded processing of the global configuration of pictures. We used two perceptual matching tasks based on the global orientation or on the colour of line drawings. Our results confirmed behavioural data. Activations in the inferior occipital cortex, fusiform and inferior temporal gyri in both tasks (orientation and colour) account for perceptual and structural processing involved in each task. In contrast, activations in the posterior and medial parts of the fusiform gyrus, shown to be involved in explicit semantic judgements, were more pronounced in the orientation-matching task, suggesting that semantic information from the pictures is processed in an implicit way even when not required by the task. Thus, this study suggests that cortical regions usually involved in explicit semantic processing are also activated when implicit processing of objects occurs.     

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.     

Emotion-cognition interactions in schizophrenia: Implicit and explicit effects of facial expression

Working memory (WM) and emotion classification are amongst the cognitive domains where specific deficits have been reported for patients with schizophrenia. In healthy individuals, the capacity of visual working memory is enhanced when the material to be retained is emotionally salient, particularly for angry faces. We investigated whether patients with schizophrenia also have an enhanced WM capacity for angry faces. We compared 34 inpatients with schizophrenia and 34 age-, handedness- and gender-matched control participants in three separate tasks. In the WM task, participants saw two faces with angry, happy or neutral emotional expressions for 2 s and had to decide whether a probe face presented after a 1 s delay was identical to one of them. In the emotion classification task, they had to assign these faces to the appropriate categorical emotion. They also rated faces for valence and arousal. Although patients performed generally worse on the working memory task, they showed the same benefit for angry faces as control participants. However, patients were specifically impaired for angry faces on the emotion classification task. These results indicate preserved implicit emotion processing in schizophrenia patients, which contrasts with their impairment in explicit emotion classification. With regard to clinical practice, our findings underline the importance of assessing responsiveness to emotions in patients with schizophrenia, with a view possibly to utilize preserved implicit emotion processing in cognitive remediation programs.     

A comparison of implicit memory tasks in Korsakoff and alcoholic patients

Korsakoff patients generally perform at a normal level on implicit memory tasks in contrast to explicit memory tasks. While this difference is sometimes explained in terms of different memory systems underlying the tasks, the different roles of perceptual and conceptual/semantic processes in these tasks have also been emphasized: explicit tasks require mainly conceptual/semantic processes and implicit tasks are based principally on perceptual processes. However, it has been suggested recently that conceptual/semantic processes may also be involved in some implicit memory tasks (e.g. a Free Association task). Therefore, the performance of Korsakoff and alcoholic patients is here compared in three implicit memory tasks (Stem Completion, Word Identification and Free Association) and one explicit memory task (Cued Recall), allowing us to disentangle what really matters: the nature of the task (implicit or explicit), or the underlying processes (perceptual or conceptual/semantic). The results show only semantic priming in the Free Association and Cued Recall tasks of the alcoholic patients, suggesting that Korsakoff patients have problems particularly with conceptually-driven processing. The implicit or explicit nature of the memory task is not critical.     

Early cortical processing of natural and artificial emotional faces differs between lower and higher socially anxious persons

Emotional facial expressions provide critical information for social interactions. Above all, angry faces are assumed to reflect potential social threat. We investigated event-related potentials (ERPs) triggered by natural and artificial faces expressing fear, anger, happiness or no emotion in participants with low and high levels of social anxiety. Overall, artificial faces elicited stronger P100 and N170 responses than natural faces. Additionally, the N170 component was larger for emotional compared to neutral facial expressions. Social anxiety was associated with an enhanced emotional modulation of the early posterior negativity (EPN) in response to fearful and angry facial expressions. Additionally, while the late positive potential (LPP) was larger for emotional than for neutral faces in low socially anxious participants, LPPs of higher socially anxious participants did not differ. LPPs might therefore be enhanced in higher socially anxious participants for both emotional and neutral faces. Furthermore, the modulations of the EPN and LPP were comparable between natural and artificial faces. These results indicate that social anxiety influences early perceptual processing of faces and that artificial faces are suitable for psychophysiological emotion research.

Event-related potentials from a visual categorization task

Investigation of the neural bases of human perceptual categorization is a continuously growing territory of visual sciences. Recently, several papers appeared on the cortical bases of human categorization performance, using functional brain imaging techniques such as positron emission tomography (PET) or functional magnetic resonance imaging (fMRI). However, the cheaper commercially available laboratory tests are not always the best methods to study multiple aspects of visual categorization. In this study, we describe the electrophysiological correlates of natural scene categorization in humans. The subject's task was to decide whether briefly presented natural scenes contained animal or non-animal items. Analysis of event-related potentials (ERPs) recorded during the categorization task, revealed more negative potentials for non-animal stimuli (NAS) in the time windows of 150-250 ms (N1) and 350-500 ms (N2), and more positive potentials for animal stimuli (AS) in the time window of 250-350 ms (P2). Our work provides an inexpensive noninvasive method to study both early perceptual and late phases of semantic information processing by recording ERPs during the categorization of natural scenes.     

Neural attention and evaluative responses to gay and lesbian couples

The goal of the current study was to examine whether differential neural attentional capture and evaluative responses for out-group homosexual relative to in-group heterosexual targets occur during social categorization. To this end, 36 heterosexual participants were presented with pictures of heterosexual and homosexual couples in a picture-viewing task that was designed to assess implicit levels of discomfort toward homosexuality and explicit evaluations of pleasantness toward the images. Neural activity in the form of electroencephalogram was recorded during the presentation of the pictures, and event-related potentials resulting from these stimuli were examined. Participants also completed questionnaires that assessed the degree to which they socialized with gays and lesbians. Results demonstrated that relative to straight couples, larger P2 amplitude was observed in response to gay but not to lesbian couples. However, both gay and lesbian couples yielded a larger late positive potential than straight couples. Moreover, the degree to which participants differentially directed early neural attention to out-group lesbian versus in-group straight couples was related to their familiarity with homosexual individuals. This work, which provides an initial understanding of the neural underpinnings of attention toward homosexual couples, suggests that differences in the processing of sexual orientation can occur as early as 200 ms and may be moderated by familiarity.     

No fear,no panic: probing negation as a means for emotion regulation

This electroencephalographic study investigated if negating one’s emotion results in paradoxical effects or leads to effective emotional downregulation. Healthy participants were asked to downregulate their emotions to happy and fearful faces by using negated emotional cue words (e.g. no fun, no fear). Cue words were congruent with the emotion depicted in the face and presented prior to each face. Stimuli were presented in blocks of happy and fearful faces. Blocks of passive stimulus viewing served as control condition. Active regulation reduced amplitudes of early event-related brain potentials (early posterior negativity, but not N170) and the late positive potential for fearful faces. A fronto-central negativity peaking at about 250 ms after target face onset showed larger amplitude modulations during downregulation of fearful and happy faces. Behaviorally, negating was more associated with reappraisal than with suppression. Our results suggest that in an emotional context, negation processing could be quite effective for emotional downregulation but that its effects depend on the type of the negated emotion (pleasant vs unpleasant). Results are discussed in the context of dual process models of cognition and emotion regulation.     

Decoding of affective facial expressions in the context of emotional situations

The ability to recognize other persons' affective states and to link these with aspects of the current situation arises early in development and is precursor functions of a Theory of Mind (ToM). Until now, studies investigated either the processing of affective faces or affective pictures. In the present study, we tried to realize a scenario more similar to every day situations. We employed fMRI and used a picture matching task to explore the neural correlates associated with the integration and decoding of facial affective expressions in the context of affective situations. In the emotion condition, the participants judged an emotional facial expression with respect to the content of an emotional picture. In the two other conditions, participants indicated colour matches on the background of either affective or scrambled pictures. In contrast to colour matching on scrambled pictures, colour matching on emotional pictures resulted in longer reaction times and increased activation of the bilateral fusiform and occipital gyrus. These results indicated that, although task irrelevant, participants may attend to the emotional background of the pictures. The emotion task was associated with higher reaction times and with activation of the bilateral fusiform and occipital gyrus. Additionally, emotion attribution induced left amygdala activity. Possibly, attention processes and amygdala projections modulated the activation found in the occipital and fusiform areas. Furthermore, the involvement of the amygdala in the ToM precursor ability to link facial expressions with an emotional situation may indicate that the amygdala is involved in the development of stable ToM abilities.     

The emotional paradox: Dissociation between explicit and implicit processing of emotional prosody in schizophrenia

People with schizophrenia show well-replicated deficits on tasks of explicit recognition of emotional prosody. However it remains unclear whether they are still sensitive to the implicit cues of emotional prosody, particularly when they exhibit high levels of social anhedonia. A dual processing model suggesting a dissociation between the neural networks involved in explicit and implicit recognition of emotional prosody has yet to be validated.21 participants with schizophrenia and 21 controls were recruited. In the explicit recognition task, individuals listened to semantically neutral words pronounced with two different emotions and judged their emotional prosody. In the vocal emotional Stroop task, patients and controls listened to words with a positive or negative emotional valence pronounced with congruent or incongruent emotional prosody and judged their emotional content. Patients were also assessed with the Chapman Anhedonia Questionnaire and the Schizophrenic Communication Disorders scale.Individuals with schizophrenia were impaired in their explicit recognition of emotional prosody related to controls. In contrast, they showed a vocal emotional Stroop effect that was identical to controls for reaction time and greater for accuracy: patients were still sensitive to implicit emotional prosody. In addition the vocal emotional Stroop score increased with social anhedonia but was unrelated to communication disorders.Whereas explicit vocal affect recognition is impaired, implicit processing of emotional prosody seems to be preserved in schizophrenia. Our results provide evidence that at a behavioural level, the implicit and explicit processing of emotional prosody can be dissociated. Remediation of emotional prosody recognition in schizophrenia should target cognitive rather than sensory processes.     

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.     

His or mine? The time course of self-other discrimination in emotion processing

This electroencephalography (EEG) study investigated at which temporal processing stages self-other discrimination in emotion processing occurs. EEG was recorded in 23 healthy participants during silent reading of unpleasant, pleasant, and neutral pronoun-noun and article--noun expressions that were related to the participants themselves, related to an unknown third person, or had no self-other reference at all. Self- and other-related pronoun--noun pairs elicited larger cortical negativity relative to the processing of article--noun pairs at left posterior electrodes as early as 200 ms after stimulus onset. In the same time windows (from 200 ms to 300 ms and 300 ms to 400 ms) the emotionality of the words enhanced event-related brain potential (ERP) amplitudes at parieto-occipital electrodes. From 350 ms onwards, processing of self-related unpleasant words elicited larger frontal negativity compared to unpleasant words that were related to the other or that had no reference at all. In addition, processing of pleasant words vs. neutral or unpleasant words elicited larger positive amplitudes over parietal electrodes from 450 ms after stimulus onset, in particular when words were self-related. Our findings demonstrate that for verbal emotional stimuli, self--other discrimination first occurs at higher-order, cortical processing stages. This is consistent with the view that categorization of information according to certain stimulus aspects (self--other reference, emotionality) occurs before its meaning is integrated.     

Is emotion processing affected by advancing age? An event-related brain potential study

The recognition of emotions is presumably affected by advancing age, which is known from subjective reports and recognition tasks. To differentiate perception from executive function more clearly, the discrimination of emotions was investigated with event-related brain potentials (ERPs) from 21 electrodes in 14 elderly (ages 59-74) and 13 younger participants (ages 30-40) triggered by a rapid (3 Hz) serial visual presentation (RSVP) of high and low arousing pictures. Additionally, affective ratings of valence and arousal of a representative sample of 54 pictures were obtained. An early posterior negativity (EPN) as an index of early emotion discrimination was analyzed in an early (168-232 ms) and a late (232-296 ms) time window. Both groups showed an EPN associated with pictures of high emotional arousal. However, the EPN was slightly delayed in elderly participants. Thus, the affective modulation of the EPN was reduced in elderly subjects in the early time window, but not in the late time window. Ratings of valence or arousal did not differ between groups. In sum, these results point towards an age-related delay of early visual emotion discrimination. However, this delay seems not to influence further evaluative processing of emotional stimuli.     

His or mine? The time course of self–other discrimination in emotion processing

This electroencephalography (EEG) study investigated at which temporal processing stages self–other discrimination in emotion processing occurs. EEG was recorded in 23 healthy participants during silent reading of unpleasant, pleasant, and neutral pronoun–noun and article–noun expressions that were related to the participants themselves, related to an unknown third person, or had no self–other reference at all. Self- and other-related pronoun–noun pairs elicited larger cortical negativity relative to the processing of article–noun pairs at left posterior electrodes as early as 200 ms after stimulus onset. In the same time windows (from 200 ms to 300 ms and 300 ms to 400 ms) the emotionality of the words enhanced event-related brain potential (ERP) amplitudes at parieto-occipital electrodes. From 350 ms onwards, processing of self-related unpleasant words elicited larger frontal negativity compared to unpleasant words that were related to the other or that had no reference at all. In addition, processing of pleasant words vs. neutral or unpleasant words elicited larger positive amplitudes over parietal electrodes from 450 ms after stimulus onset, in particular when words were self-related. Our findings demonstrate that for verbal emotional stimuli, self–other discrimination first occurs at higher-order, cortical processing stages. This is consistent with the view that categorization of information according to certain stimulus aspects (self–other reference, emotionality) occurs before its meaning is integrated.