Emotion-Related Visual Mismatch Responses in Schizophrenia: Impairments and Correlations with Emotion Recognition.

BACKGROUND AND OBJECTIVES:Mismatch negativity (MMN) is an event-related potential (ERP) measure of preattentional sensory processing. While deficits in the auditory MMN are robust electrophysiological findings in schizophrenia, little is known about visual mismatch response and its association with social cognitive functions such as emotion recognition in schizophrenia. Our aim was to study the potential deficit in the visual mismatch response to unexpected facial emotions in schizophrenia and its association with emotion recognition impairments, and to localize the sources of the mismatch signals. EXPERIMENTAL DESIGN:The sample comprised 24 patients with schizophrenia and 24 healthy control subjects. Controls were matched individually to patients by gender, age, and education. ERPs were recorded using a high-density 128-channel BioSemi amplifier. Mismatch responses to happy and fearful faces were determined in 2 time windows over six regions of interest (ROIs). Emotion recognition performance and its association with the mismatch response were also investigated. PRINCIPAL OBSERVATIONS:Mismatch signals to both emotional conditions were significantly attenuated in patients compared to controls in central and temporal ROIs. Controls recognized emotions significantly better than patients. The association between overall emotion recognition performance and mismatch response to the happy condition was significant in the 250-360 ms time window in the central ROI. The estimated sources of the mismatch responses for both emotional conditions were localized in frontal regions, where patients showed significantly lower activity. CONCLUSIONS:Impaired generation of mismatch signals indicate insufficient automatic processing of emotions in patients with schizophrenia, which correlates strongly with decreased emotion recognition

Processing of unattended facial emotions: A visual mismatch negativity study

Facial emotions express our internal states and are fundamental in social interactions. Here we explore whether the repetition of unattended facial emotions builds up a predictive representation of frequently encountered emotions in the visual system. Participants (n = 24) were presented peripherally with facial stimuli expressing emotions while they performed a visual detection task presented in the center of the visual field. Facial stimuli consisted of four faces of different identity, but expressed the same emotion (happy or fearful). Facial stimuli were presented in blocks of oddball sequence (standard emotion: p = 0.9, deviant emotion: p = 0.1). Event-related potentials (ERPs) to the same emotions were compared when the emotions were deviant and standard, respectively. We found visual mismatch negativity (vMMN) responses to unattended deviant emotions in the 170–360 ms post-stimulus range over bilateral occipito-temporal sites. Our results demonstrate that information about the emotional content of unattended faces presented at the periphery of the visual field is rapidly processed and stored in a predictive memory representation by the visual system. We also found evidence that differential processing of deviant fearful faces starts already at 70–120 ms after stimulus onset. This finding shows a ‘negativity bias’ under unattended conditions. Differential processing of fearful deviants were more pronounced in the right hemisphere in the 195–275 ms and 360–390 ms intervals, whereas processing of happy deviants evoked larger differential response in the left hemisphere in the 360–390 ms range, indicating differential hemispheric specialization for automatic processing of positive and negative affect

Event-related theta synchronization predicts deficit in facial affect recognition in schizophrenia

Growing evidence suggests that abnormalities in the synchronized oscillatory activity of neurons in schizophrenia may lead to impaired neural activation and temporal coding and thus lead to neurocognitive dysfunctions, such as deficits in facial affect recognition. To gain an insight into the neurobiological processes linked to facial affect recognition, we investigated both induced and evoked oscillatory activity by calculating the Event Related Spectral Perturbation (ERSP) and the Inter Trial Coherence (ITC) during facial affect recognition. Fearful and neutral faces as well as nonface patches were presented to 24 patients with schizophrenia and 24 matched healthy controls while EEG was recorded. The participants’ task was to recognize facial expressions. Because previous findings with healthy controls showed that facial feature decoding was associated primarily with oscillatory activity in the theta band, we analyzed ERSP and ITC in this frequency band in the time interval of 140–200 ms, which corresponds to the N170 component. Event-related theta activity and phase-locking to facial expressions, but not to nonface patches, predicted emotion recognition performance in both controls and patients. Event-related changes in theta amplitude and phase-locking were found to be significantly weaker in patients compared with healthy controls, which is in line with previous investigations showing decreased neural synchronization in the low frequency bands in patients with schizophrenia. Neural synchrony is thought to underlie distributed information processing. Our results indicate a less effective functioning in the recognition process of facial features, which may contribute to a less effective social cognition in schizophrenia

Fearful face recognition in schizophrenia: An electrophysiological study

BACKGROUND: Emotional expressions are important acts of communication, and impairment in facial emotion recognition has been shown to be related to impairments in social cognition in schizophrenia. We used an event-related potential (ERP) paradigm to identify and delineate the temporal characteristics in the electrophysiological cascade related to fearful facial affect processing in patients with schizophrenia as compared to healthy controls. METHODS: Twenty-four subjects with schizophrenia and 24 individually matched healthy controls participated in an emotion recognition task. Ekman faces displaying neutral and fearful facial expressions were used as stimuli. ERPs were recorded using a 128-channel EEG system. RESULTS: Based on the analysis of Global Field Power (GFP) in the 150-190ms time window both groups differentiated between fearful and neutral faces. Schizophrenia patients showed an additional differential processing of fearful vs. neutral faces in the 330-450ms time window, and this ERP effect correlated with psychopathology. CONCLUSIONS: Both patients and healthy controls differentiate fearful and neutral faces in early phases of emotion processing. Our results also indicate that schizophrenia patients show increased responsivity to fearful faces at a later processing stage. This could be related to the overrating of negative emotions, and the symptomatology associated with fear processing in patients with schizophrenia

Stimuli and paradigm.

<p>Schematic illustration of the pattern of emotional stimuli used in the experiment. Four individual photographs displaying the same facial affect were presented on each screen for 200-stimulus interval randomly varying between 450–650 ms during which occasionally the vertical and horizontal lines of the fixation cross changed. The subjects’ task was a speeded button-press to the changes of the cross.</p

Results of the source localization for the happy condition.

<p>Red color indicates significant group differences in mismatch generation to the happy condition in the 250–360 ms time window. (HC = Healthy Controls, SZ = Patients with Schizophrenia).</p

Antipsychotic medications.

*<p>Weekly dose.</p

Source Localization of the Mismatch Signals.

*<p>p<0.05, two-tailed, ⁽*⁾ p<0.1, two-tailed.</p>1<p>Areas listed by t_max in decreasing order.</p

Event-related potentials and mismatch waveforms by region.

<p>HC = Healthy Controls, SZ = Patients with Schizophrenia. Upper panel: ERPs for fearful faces; lower panel: ERPs for happy faces. Shaded intervals indicate time windows of amplitude measurements. Only those ROIs were used for between-group comparison where the mismatch waveform in at least one of the study groups differed significantly from zero after correction for multiple testing. Asterisks mark time windows where significantly larger mismatch responses were found in the healthy control group compared to the patients.</p