Intact motivated attention in schizophrenia: evidence from event-related potentials

Emotionally significant stimuli typically capture attention (called motivated attention) even when they are irrelevant to tasks where attention is directed. Previous studies indicate that several components of emotional processing are intact in schizophrenia when subjects are instructed to attend to emotionally-evocative stimuli. However, few studies have examined whether emotional stimuli capture attention to a normal degree in people with schizophrenia when attention is directed elsewhere. The current event-related potential study examined motivated attention to task-irrelevant emotional stimuli in 35 stabilized outpatients and 26 healthy controls with a modified visual P300 oddball detection task. Participants viewed images of rare target and commonly occurring standard letter stimuli, as well as intermixed emotional (unpleasant, pleasant, neutral) pictures. Subjects were instructed to count the number of rare targets; the emotional valence of the picture stimuli was, therefore, task-irrelevant. We separately evaluated the Early Posterior Negativity (EPN) and Late Positive Potential (LPP) to emotional pictures and the P300 to target stimuli. Patients and controls showed similar patterns of EPN and LPP amplitude to the emotional stimuli, such that the EPN and LPP were larger for both pleasant and unpleasant versus neutral pictures. Although patients performed worse than controls on the target counting task, both groups showed comparable P300 differentiation between target versus non-target stimuli. Emotional stimuli captured attentional resources in people with schizophrenia even when the emotional stimuli were task-irrelevant, suggesting intact motivated attention at the level of early electrophysiological responding.     

Affective reactivity in heroin-dependent patients with antisocial personality disorder

The Antisocial personality disorder (ASPD), one of the most common co-morbid psychiatric disorders in heroin-dependent patients, is associated with a lack of affective modulation. The present study aimed to compare the affect-modulated startle responses of opioid-maintained heroin-dependent patients with and without ASPD relative to those of healthy controls. Sixty participants (20 heroin-dependent patients with ASPD, 20 heroin-dependent patients without ASPD, 20 healthy controls) were investigated in an affect-modulated startle experiment. Participants viewed neutral, pleasant, unpleasant, and drug-related stimuli while eye-blink responses to randomly delivered startling noises were recorded continuously. Both groups of heroin-dependent patients exhibited significantly smaller startle responses (raw values) than healthy controls. However, they showed a normal affective modulation: higher startle responses to unpleasant, lower startle responses to pleasant stimuli and no difference to drug-related stimuli compared to neutral stimuli. These findings indicate a normally modulated affective reactivity in heroin-dependent patients with ASPD.     

Motivated attention to cocaine and emotional cues in abstinent and current cocaine users--an ERP study

Event-related potentials (ERPs) are a direct measure of neural activity and are ideally suited to study the time-course of attentional engagement with emotional and drug-related stimuli in addiction. In particular, the late positive potential (LPP) appears to be enhanced following cocaine-related compared with neutral stimuli in human participants with cocaine use disorders (CUD). However, previous studies have not directly compared cocaine-related with emotional stimuli while examining potential differences between abstinent and current cocaine users. The present study examined ERPs in 55 CUD (27 abstinent and 28 current users) and 29 matched healthy controls while they passively viewed pleasant, unpleasant, neutral and cocaine-related pictures. To examine the time-course of attention to these stimuli, we analysed both an early and later window in the LPP as well as the early posterior negativity (EPN), established in assessing motivated attention. Cocaine pictures elicited increased electrocortical measures of motivated attention in ways similar to affectively pleasant and unpleasant pictures in all CUD, an effect that was no longer discernible during the late LPP window for the current users. This group also exhibited deficient processing of the other emotional stimuli (early LPP window - pleasant pictures; late LPP window - pleasant and unpleasant pictures). Results were unique to the LPP and not EPN. Taken together, results support a relatively early attention bias to cocaine stimuli in cocaine-addicted individuals, further suggesting that recent cocaine use decreases such attention bias during later stages of processing but at the expense of deficient processing of other emotional stimuli.     

Emotionally arousing stimuli compete for attention with left hemispace

Rapid interaction of the emotional and attentional networks is critical for adaptive behavior. Here, we examined the effects of emotional stimulation on hemifield attention allocation using event-related potential and behavioral measures. Participants performed a visual-discrimination task on nonemotional targets presented randomly in the left or right hemifield. A brief task-irrelevant emotional (pleasant or unpleasant; 150-ms duration) or neutral picture was presented centrally 350 ms before the next target (150-ms duration). Unpleasant stimuli interfered with the left visual field attention capacity, slowing behavioral responses to attended left field stimuli. In keeping with the behavioral data, event-related potential responses to nonemotional attended left field stimuli were reduced over the right parietal regions when preceded by an unpleasant event. The results provide electrophysiological and behavioral evidence that unpleasant, emotionally arousing stimuli interfere with the right hemisphere-dependent attention capacity.     

Event-related potentials to emotional stimuli in migrainous children

The present preliminary study was aimed at investigating the electrocortical correlates of attentional allocation toward emotional stimuli in children and adolescents with migraine by means of the event-related potentials. The electroencephalogram was continuously recorded in 7 migrainous children and 8 healthy controls while they were looking at a series of pleasant, neutral, and unpleasant pictures. The mean amplitude of the Negative Central component of the event-related potentials was computed as an index of the allocation of attentional resources to the presented stimuli. Relative to controls, children with migraine displayed reduced fronto-central negativity and larger posterior positivity in response to emotional pictures. This effect was already evident, overall, in a time window preceding the Negative Central component. The smaller cortical negativity in response to emotional stimuli suggests reduced attentional engagement toward emotionally relevant stimuli, or might be interpreted in terms of advanced brain maturation in migraine children.     

Affective modulation of somatosensory-evoked potentials elicited by tactile stimulation

The present investigation was aimed to evaluate the influence of emotional valence on brain correlates of non-painful somatosensory processing. For this purpose, we examined changes on the somatosensory-evoked potentials (SEP) elicited by frequent and deviant tactile stimuli (probability 14%) when subjects were viewing affective pictures. Twenty healthy volunteers aged between 19 and 47 years old participated in the study. The P50, N80, and P200 components of the SEP, as well as the P200 component of the visual-evoked potentials (VEP) elicited by the affective pictures were analyzed. Overall, a significant P50 amplitude reduction was observed when subjects were viewing unpleasant pictures, in comparison to pleasant pictures. Furthermore, larger SEP amplitudes were obtained in response to the deviant than to the frequent stimuli. In addition, unpleasant pictures elicited larger P200 amplitudes of the VEP than pleasant. Data suggest that affective stimuli may modulate the early processing of somatosensory information in the brain, probably reflecting the existence of an adaptive perceptual/attentional mechanism to motivationally relevant stimuli.     

Affective modulation of the startle reflex in schizophrenic patients

Startle-elicited blinks were measured during the presentation of affective slides in order to investigate emotional responsiveness in 24 male healthy subjects and 34 male schizophrenic patients. Although the two groups did not differ with regard to their subjective and autonomic responses to the slide stimuli, there was a significant difference between the groups in their responses to the startle probes. Patients rated low in affective expression showed a linear response pattern comparable to that of normal controls with largest amplitudes during unpleasant slides and smallest during pleasant slides. Patients without apparent deficit in affective expression showed a quadratic relationship with smaller blink amplitudes during both pleasant and unpleasant slides. Diminished affective expression rated on the basis of a clinical interview is not associated with a general attenuation of the blink reflex or of its modulation by exposure to emotional slides. Thus, we found no indication of an impairment in the perception of affective stimuli nor of reduced appreciation of pleasant stimuli (anhedonia) in these patients.     

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 500 ms 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.     

The late positive potential predicts subsequent interference with target processing

The current study investigated the association between neural engagement with task-irrelevant images and subsequent interference with target processing using the Emotional Interrupt paradigm [Mitchell, D., Richell, R., Leonard, A., & Blair, R. Emotion at the expense of cognition: Psychopathic individuals outperform controls on an operant response task. Journal of Abnormal Psychology, 115, 559, 2006]. Consistent with previous studies, PCA-derived factors corresponding to the early posterior negativity, P300, and late positive potential (LPP) were enhanced for emotional (i.e., both unpleasant and pleasant) compared with neutral distracters, and the P300 elicited by targets was smaller following emotional compared with neutral pictures. In addition, RTs were increased to targets that followed emotional pictures. Within-subject analyses demonstrated that slow trials were characterized by a smaller P300 and were preceded by pictures with a larger LPP. Additionally, between-subject analyses indicate that individuals with a larger LPP also demonstrated slower RTs to targets and reduced target-elicited P300s. All results were specific to the LPP and were not observed for either the early posterior negativity or the P300 elicited by task-irrelevant pictures. By relating the LPP to subsequent behavioral and ERP interference in both within- and between-subject analyses, the current study provides direct support for the notion that LPP indexes attentional engagement with visual stimuli that is uniquely associated with subsequent interference in terms of both RT slowing and P300 reduction to targets.     

Cerebral blood flow changes associated with attribution of emotional valence to pleasant, unpleasant, and neutral visual stimuli in a PET study of normal subjects.

OBJECTIVE: To assist in the development of a model for the psychopathology of emotions, the present study sought to identify the neural circuits associated with the evaluation of visual stimuli for emotional valence. METHOD: Seventeen healthy individuals were shown three sets of emotionally laden pictures carrying pleasant, unpleasant, and neutral content. While subjects evaluated the picture set for emotional valence, regional cerebral blood flow was measured with the use of [15O] water positron emission tomography. Subjective ratings of the emotional valence of the picture sets were recorded. Data were analyzed by comparing the images acquired during the neutral condition with the unpleasant and pleasant image sets and the unpleasant and pleasant conditions with each other. RESULTS: Processing of pleasant stimuli was associated with increased blood flow in the dorsal-lateral, orbital, and medial frontal cortex relative to the unpleasant condition and in the cingulate, precuneus, and visual cortex relative to the neutral condition. Evaluation of unpleasant stimuli activated the amygdala, visual cortex, and cerebellum relative to the pleasant condition and the nucleus accumbens, precuneus, and visual cortex relative to the neutral condition. CONCLUSIONS: Observing and assigning emotional value to unpleasant stimuli produced activations in subcortical limbic regions, whereas evaluation of pleasant stimuli produced activations in cortical limbic areas. These findings are consistent with the notion of a subcortical and archaic danger recognition system and a system detecting pleasantness in events and situations that is phylogenetically younger, involving primarily the prefrontal cortex.     

Modulation of subthalamic alpha activity to emotional stimuli correlates with depressive symptoms in Parkinson's disease1

Background : Deep brain stimulation of the subthalamic nucleus is an effective treatment for patients with advanced Parkinson's disease. However, affective side effects following subthalamic deep brain stimulation have been reported. Here, we aim to elucidate the influence of affective state on emotional processing as indexed by local field potential activity and to identify neurophysiological markers in patients at risk of developing depressive symptoms during subthalamic deep brain stimulation. Methods : Subthalamic local field potentials were directly recorded via electrodes implanted for deep brain stimulation in 12 Parkinson's disease patients while viewing emotionally salient and neutral pictures. Parkinson's disease patients were assessed for depressive symptoms using the Beck depression inventory at the time of operation and 3 months after continuous subthalamic nucleus deep brain stimulation. Results : We found a significant event‐related desynchronization in the local alpha frequency band (8–12 Hz) for emotionally arousing but not neutral pictures. The the event‐related desynchronization (ERD) in the alpha frequency band was reduced for pleasant stimuli in patients with mild to moderate depressive symptoms compared with patients without depression. The alpha‐ERD to unpleasant stimuli showed the opposite pattern. Consistently, the index of event‐related alpha desynchronization (alpha ERD for pleasant stimuli minus alpha ERD for unpleasant stimuli) correlated with the Beck depression inventory at the time of the recordings and at 3 months after continuous deep brain stimulation. The alpha ERD to unpleasant pictures correlated significantly with the Beck depression inventory score at 3 months after chronic deep brain stimulation. Discusion : In conclusion, we found mood‐congruent stimulus processing in the subthalamic nucleus of Parkinson's disease patients. Electrophysiological markers such as event‐related desynchronization of subthalamic alpha activity reflect state‐dependent emotional processing and may potentially be used to predict depressive mood disturbances in Parkinson's disease patients with chronic subthalamic deep brain stimulation at an early stage. © 2011 Movement Disorder Society     

Emotional information processing in first and recurrent major depressive episodes

Depressive states are classically associated to increased sensitivity to negative events. However this hypersensitivity may not be stable in time, being absent in remission periods or further reinforced with recurrent depressive episodes, or may concern positive stimuli instead, e.g. in young depressive patients. To study the evolution of the processing of emotional information in depression we recorded late components of evoked potentials in first-episode and recurrent depressed patients before and after recovery. We used a visual attentional paradigm manipulating the processing of emotional information. Subjects first counted words with positive valence, and then words with negative valence from lists of usual words. The results showed that recurrent patients had increased P300 amplitudes for negative words selection only in negative words counting situation, while first-episode patients had decreased P300 amplitudes for positive words selection. After clinical improvement, the negative biases in recurrent patients group disappeared but P300 amplitudes of first-episode patients remained significantly low for positive words. First-episode depressed patients show a selective impairment for positive stimuli, with decreased response to pleasant stimuli, while recurrent depressive subjects show signs of hyperesthesia for negative stimuli. These results suggest that responses to emotional stimuli in word processing are related to the duration of the mood disorders.     

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.     

Emotional picture processing in children: an ERP study

The late positive potential (LPP) reflects increased attention to emotional versus neutral stimuli in adults. To date, very few studies have examined the LPP in children, and whether it can be used to measure patterns of emotional processing that are related to dispositional mood characteristics, such as temperamental fear and anxiety. To examine this question,39 typically developing 5–7 year olds (M age in months = 75.27, SD = 5.83) passively viewed complex emotional and neutral pictures taken from the International Affective Picture System.Maternal report of temperamental fear and anxiety was obtained and fearful behavior during an emotional challenge was observed. As documented in adults, LPP amplitudes to pleasant and unpleasant stimuli were larger than to neutral stimuli, although some gender differences emerged. Larger LPP amplitude differences between unpleasant and neutral stimuli were associated with greater observed fear. The LPP as a measure of individual differences in emotional processing is discussed.     

Transient interference of right hemispheric function due to automatic emotional processing

We examined the effects of emotional stimuli on right and left hemisphere detection performance in a hemifield visual discrimination task. A group of 18 healthy subjects were asked to discriminate between upright and inverted triangles (target). Targets were randomly presented in the left or right visual hemifield (150 ms target duration). A brief emotional picture (pleasant or unpleasant; 150 ms stimulus duration) or neutral picture selected from the International Affective Picture System was randomly presented either in the same (47%) or the opposite (47%) spatial location to the subsequent target. Emotional or neutral stimuli offset 150 ms prior to the subsequent target. Subjects were instructed to ignore the pictures and respond to the targets as quickly and accurately as possible. Independent of field of presentation, emotional stimuli prolonged reaction times (P < 0.01) to LVF targets, with unpleasant stimuli showing a greater effect than pleasant stimuli. The current study shows that brief emotional stimuli selectively impair right hemispheric visual discrimination capacity. The findings suggest automatic processing of emotional stimuli captures right hemispheric processing resources and transiently interferes with other right hemispheric functions.     

On the relationship between interoceptive awareness, emotional experience, and brain processes

The perception of visceral signals plays a crucial role in many theories of emotions. The present study was designed to investigate the relationship between interoceptive awareness and emotion-related brain activity. 44 participants (16 male, 28 female) first underwent a heartbeat perception task and then were categorised either as good (n = 22) or poor heartbeat perceivers (n = 22). A total of 60 different pictures (pleasant, unpleasant, neutral) from the International Affective Picture System served as emotional stimuli. EEG (61 electrodes) and EOG were recorded during slide presentation. After each slide, the subjects had to rate emotional valence and arousal on a 9-point self-report scale. Good heartbeat perceivers scored the emotional slides significantly more arousing than poor heartbeat perceivers; no differences were found in the emotional valence ratings. The visually evoked potentials of good and poor heartbeat perceivers showed significant differences in the P300 and in the slow-wave latency ranges. Statistical analyses revealed significantly higher P300 mean amplitudes for good heartbeat perceivers (averaged across all 60 slides) than for poor heartbeat perceivers. In the slow-wave range, this effect was found for affective slides only. Heartbeat perception scores correlated significantly and positively with both the mean arousal rating as well as with the mean amplitudes in the P300 time window and the slow-wave window. Our results demonstrate a strong relationship between the perception of cardiac signals and the cortical processing of emotional stimuli, as would be postulated for example by the James-Lange theory of emotions.     

Multisensory integration of emotionally valenced olfactory–visual information in patients with schizophrenia and healthy controls

Background

Patients with schizophrenia frequently have deficits in social cognition, and difficulties in the discrimination of emotional facial expressions have been discussed as an important contributing factor. We investigated whether this impairment is aggravated by difficulties relating the observed facial expression to contextual information, as is often provided by emotionally valenced crossmodal stimulation.

Methods

We investigated the effects of odorant primes on the accuracy and speed of emotional face recognition. Healthy controls and patients with schizophrenia were exposed to 2-second odorant stimuli: vanillin (pleasant), ambient air (neutral) and hydrogen sulfide (unpleasant). The odours were followed by an emotional face recognition task, in which participants determined if a face showed happiness, disgust or neutral affect.

Results

Controls showed improved performance in the categorization of disgusted faces after all types of odour stimulation irrespective of the emotional valence. However, in controls, the response time for happy faces was slower after presentation of any odour. Schizophrenia patients showed an attenuated effect of olfactory priming on disgust recognition, which resulted in the increased performance differences between the groups. This effect was particularly strong for the unpleasant odour.

Limitations

The study design did not allow us to fully differentiate between the effects of perceived odour intensity and valence. A possible contribution of cognitive deficits on the observed effects should be investigated in future studies.

Conclusion

Our results provide novel evidence for a special connection between the presentation of odorant cues and the accuracy of recognition of disgusted faces in healthy controls. This recognition advantage is disturbed in patients with schizophrenia and appears to contribute to the observed deficit in emotional face recognition.     

Brain activity during expectancy of emotional stimuli: an fMRI study

We studied the neural activation associated with the expectancy of emotional stimuli using whole brain fMRI. Fifteen healthy subjects underwent fMRI scanning during which they performed a warned reaction task using emotional pictures carrying pleasant, unpleasant, or neutral content. The task involved an expected or unexpected condition. Data were analyzed by comparing the images acquired under the different conditions. In the expected condition, compared with the unexpected condition, significant activation was observed in the medial, inferior and dorsolateral prefrontal cortex. Whereas the expectancy of pleasant stimuli produced activation in the left dorsolateral and left medial prefrontal cortex as well as in the right cerebellum, the expectancy of unpleasant stimuli produced activation in the right inferior and right medial prefrontal cortex, the right amygdala, the left anterior cingulate cortex, and bilaterally in the visual cortex. These results suggest that the expectancy of emotional stimuli is mediated by the prefrontal area including the medial, inferior, and dorsolateral prefrontal cortex. Furthermore, our data suggest that left frontal activation is associated with the expectancy of pleasant stimuli and that right frontal activation is associated with the expectancy of unpleasant stimuli. Finally, our findings suggest that the amygdala and anterior cingulate cortex may play an important role in the expectancy of unpleasant stimuli and that the input of this negative information is modulated by these specific brain areas.     

Orbitofrontal cortex biases attention to emotional events

We examined the role of orbitofrontal (OF) cortex in regulating emotion-attention interaction and the balance between involuntary and voluntary attention allocation. We studied patients with OF lesion applying reaction time (RT) and event-related potential (ERP) measures in a lateralized visual discrimination task with novel task-irrelevant affective pictures (unpleasant, pleasant, or neutral) preceding a neutral target. This allowed for comparing the effects of automatic attention allocation to emotional versus neutral stimuli on subsequent voluntary attention allocation to target stimuli. N2-P3a and N2-P3b ERP components served as measures of involuntary and voluntary attention allocation correspondingly. Enhanced N2-P3a amplitudes to emotional distractors and reduced N2-P3b amplitudes to targets preceded by emotional distractors were observed in healthy subjects, suggesting automatic emotional orienting interfered with subsequent voluntary orienting. OF patients showed an opposite pattern with tendency towards reduced N2-P3a responses to emotional distractors, suggesting impaired automatic orienting to emotional stimuli due to orbitofrontal damage. Enhanced N2-P3b responses to targets preceded by any affective distractor were observed in OF patients, suggesting bias towards voluntary target-related attention allocation due to orbitofrontal lesion. Behavioral evidence indicated that left visual field (LVF) attention performance was modulated by emotional stimuli. Specifically, OF patients responded faster to LVF targets subsequent to pleasant emotional distractors. We suggest that damage to the orbitofrontal circuitry leads to dysbalance between voluntary and involuntary attention allocation in the context of affective distractors with predisposition to posterior target-related processing over frontal novelty and affect-related processing. Furthermore, we suggest that orbitofrontal influence on emotion-attention interaction is valence and hemisphere dependent.     

Self-reference modulates the processing of emotional stimuli in the absence of explicit self-referential appraisal instructions

Self-referential evaluation of emotional stimuli has been shown to modify the way emotional stimuli are processed. This study aimed at a new approach by investigating whether self-reference alters emotion processing in the absence of explicit self-referential appraisal instructions. Event-related potentials were measured while subjects spontaneously viewed a series of emotional and neutral nouns. Nouns were preceded either by personal pronouns (‘my’) indicating self-reference or a definite article (‘the’) without self-reference. The early posterior negativity, a brain potential reflecting rapid attention capture by emotional stimuli was enhanced for unpleasant and pleasant nouns relative to neutral nouns irrespective of whether nouns were preceded by personal pronouns or articles. Later brain potentials such as the late positive potential were enhanced for unpleasant nouns only when preceded by personal pronouns. Unpleasant nouns were better remembered than pleasant or neutral nouns when paired with a personal pronoun. Correlation analysis showed that this bias in favor of self-related unpleasant concepts can be explained by participants’ depression scores. Our results demonstrate that self-reference acts as a first processing filter for emotional material to receive higher order processing after an initial rapid attention capture by emotional content has been completed. Mood-congruent processing may contribute to this effect.