Oxytocin attenuates feelings of hostility depending on emotional context and individuals' characteristics

In humans, oxytocin (OT) enhances prosocial behaviour. However, it is still unclear how the prosocial effects of OT are modulated by emotional features and/or individuals' characteristics. In a placebo-controlled design, we tested 20 healthy male volunteers to investigate these behavioural and neurophysiological modulations using magnetoencephalography. As an index of the individuals' characteristics, we used the empathy quotient (EQ), the autism spectrum quotient (AQ), and the systemising quotient (SQ). Only during the perception of another person's angry face was a higher SQ a significant predictor of OT-induced prosocial change, both in the behavioural and neurophysiological indicators. In addition, a lower EQ was only a significant predictor of OT-induced prosocial changes in the neurophysiological indicators during the perception of angry faces. Both on the behavioural and the neurophysiological level, the effects of OT were specific for anger and correlated with a higher SQ

Beta event-related desynchronization as an index of individual differences in processing human facial expression: further investigations of autistic traits in typically developing adults

The human mirror neuron system (hMNS) has been associated with various forms of social cognition and affective processing including vicarious experience. It has also been proposed that a faulty hMNS may underlie some of the deficits seen in the autism spectrum disorders (ASDs). In the present study we set out to investigate whether emotional facial expressions could modulate a putative EEG index of hMNS activation (mu suppression) and if so, would this differ according to the individual level of autistic traits [high versus low Autism Spectrum Quotient (AQ) score]. Participants were presented with 3 s films of actors opening and closing their hands (classic hMNS mu-suppression protocol) while simultaneously wearing happy, angry, or neutral expressions. Mu-suppression was measured in the alpha and low beta bands. The low AQ group displayed greater low beta event-related desynchronization (ERD) to both angry and neutral expressions. The high AQ group displayed greater low beta ERD to angry than to happy expressions. There was also significantly more low beta ERD to happy faces for the low than for the high AQ group. In conclusion, an interesting interaction between AQ group and emotional expression revealed that hMNS activation can be modulated by emotional facial expressions and that this is differentiated according to individual differences in the level of autistic traits. The EEG index of hMNS activation (mu suppression) seems to be a sensitive measure of the variability in facial processing in typically developing individuals with high and low self-reported traits of autism

The Functional Role of Neural Oscillations in Non-Verbal Emotional Communication

Effective interpersonal communication depends on the ability to perceive and interpret nonverbal emotional expressions from multiple sensory modalities. Current theoretical models propose that visual and auditory emotion perception involves a network of brain regions including the primary sensory cortices, the superior temporal sulcus (STS), and orbitofrontal cortex (OFC). However, relatively little is known about how the dynamic interplay between these regions gives rise to the perception of emotions. In recent years, there has been increasing recognition of the importance of neural oscillations in mediating neural communication within and between functional neural networks. Here we review studies investigating changes in oscillatory activity during the perception of visual, auditory, and audiovisual emotional expressions, and aim to characterize the functional role of neural oscillations in nonverbal emotion perception. Findings from the reviewed literature suggest that theta band oscillations most consistently differentiate between emotional and neutral expressions. While early theta synchronization appears to reflect the initial encoding of emotionally salient sensory information, later fronto-central theta synchronization may reflect the further integration of sensory information with internal representations. Additionally, gamma synchronization reflects facilitated sensory binding of emotional expressions within regions such as the OFC, STS, and, potentially, the amygdala. However, the evidence is more ambiguous when it comes to the role of oscillations within the alpha and beta frequencies, which vary as a function of modality (or modalities), presence or absence of predictive information, and attentional or task demands. Thus, the synchronization of neural oscillations within specific frequency bands mediates the rapid detection, integration, and evaluation of emotional expressions. Moreover, the functional coupling of oscillatory activity across multiples frequency bands supports a predictive coding model of multisensory emotion perception in which emotional facial and body expressions facilitate the processing of emotional vocalizations

Localizing evoked and induced responses to faces using magnetoencephalography

A rich pattern of responses in frequency, time and space are known to be generated in the visual cortex in response to faces. Recently, a number of studies have used magnetoencephalography (MEG) to try to record these responses non-invasively – in many cases using source analysis techniques based on the beamforming method. Here we sought both to characterize best practice for measuring face-specific responses using MEG beamforming, and to determine whether the results produced by the beamformer match evidence from other modalities. We measured activity to visual presentation of face stimuli and phase-scrambled control stimuli, and performed source analyses of both induced and evoked responses using Synthetic Aperture Magnetometry. We localized the gamma-band response to bilateral lateral occipital cortex, and both the gamma-band response and the M170-evoked response to the right fusiform gyrus. Differences in the gamma-band response between faces and scrambled stimuli were confined to the frequency range 50–90 Hz; gamma-band activity at higher frequencies did not differ between the two stimulus categories. We additionally identified a component of the M220-evoked response – localized to the parieto-occipital sulcus – which was enhanced for scrambled vs. unscrambled faces. These findings help to establish that MEG beamforming can localize face-specific responses in time, frequency and space with good accuracy (when validated against established findings from functional magnetic resonance imaging and intracranial recordings), as well as contributing to the establishment of best methodological practice for the use of the beamformer method to measure face-specific responses

Motivational underpinnings of negative affect as revealed by emotional modulation of EEG bands

The studies reported in this thesis pertain to a project aiming at investigating the motivational underpinnings of psychopathologies characterized by negative affect, such as anxiety and depression. Unbalanced or conflicting motivational tendencies can lead to disturbances in emotional responding and ongoing affect, which are often associated with psychopathology. As it will be introduced in the first chapter, motivational drives are thought to be sustained by two main systems in the brain, namely the appetitive and the defensive motivational circuits. The appetitive system contributes to approach behaviors in response to rewarding and pleasant stimuli. On the other side, the defensive system drives withdrawal from threat and is important for triggering unpleasant emotions. Therefore, emotions can be described as action dispositions reflecting basic tendencies to both approach and withdrawal in response to emotional stimuli. Several models postulated that negative affect in psychopathology arises from an excessive activation of the defensive system, which leads to an increased and dominant tendency to actively withdrawal from potential threats in the environment. Partially contrasting with this theoretical conceptualization, the aim of this thesis was to investigate whether negative affect could also manifest in psychopathologies which are not characterized by a straightforward increase in withdrawal tendencies. In this sense, EEG correlates of motivational tendencies in response to emotional stimuli were investigated in blood phobia and in dysphoria (i.e., subclinical depression). Accordingly, blood phobia, contrary to other specific phobias, is not associated with an increase in action disposition in response to the feared stimulus. Therefore, negative affect in these individuals does not seem to arise from a pronounced tendency to actively withdrawal. Depression represents another example of condition in which it is not clear whether negative affect is subtended by a dominance of the withdrawal system or by a lack in appetitive motivation. Accordingly, it is matter of debate whether depressed mood is due to preferential processing of unpleasant stimuli or reduced sensitivity to rewards and positive emotions. In order to investigate these aspects, three studies were conducted. In study 1, it was chosen to investigate modulation of EEG bands during an emotional Go/Nogo task in blood phobia. The emotional Go/Nogo task, including phobia-related pictures, along with phobia-unrelated unpleasant, neutral and pleasant stimuli, was ideal to investigate the lack of action disposition in blood phobia. Results showed that individuals with blood phobia display a conflicting motivational pattern, characterized by co-occurring tendencies to attend and avoid the feared stimulus, in strong contrast with other phobias. In Studies 2 and 3, modulation of EEG bands during an emotional imagery task in individuals with dysphoria was investigated. The emotional imagery is an active task, in which individuals are requested to actively imagine emotional scenarios; therefore it was well suited to investigate emotional modulation of appetitive and defensive motivational tendencies. Overall, results supported the idea that depressed mood in dysphoria is due to a lack in appetitive motivation, accompanied by a reduction in processing of pleasant stimuli. Again, we found no evidences of increased defensive motivation and tendency to withdrawal in dysphoric individuals. Finally, our research focused on possible clinical implications of the abovementioned findings, concerning the application of bio-behavioral trainings for the reduction of negative affect. In line with the pertaining literature, results from of our first three studies showed that frontal alpha asymmetry is an informative index of motivational tendencies underlying affect and emotional responses. Therefore, a fourth study was conducted, aimed at evaluating the effectiveness of a frontal alpha asymmetry neurofeedback training in reducing negative affect, anxiety and depressive symptoms in healthy individuals. After five training sessions, healthy individuals succeeded in reducing right compared to left prefrontal activity, through a specific increase in right frontal alpha. In accordance with the role of the right prefrontal cortex in defensive motivation and negative affect, this increase in right frontal alpha power was associated with a significant reduction in negative affect and anxiety. In conclusion, the present thesis confirms and extends the link between motivational tendencies and negative affect, showing that negative affect is not exclusively associated with an increase in defensive motivation and in active withdrawal disposition. Accordingly, among psychopathologies characterized by negative affect, blood phobia and dysphoria do not display the typically predicted motivational pattern. A first step toward the transition from basic research to clinical application has been proposed, with the implementation of an EEG-based neurofeedback for the reduction of negative affect. Overall, the present work is of potential relevance for a better understanding of the motivational underpinnings of psychopathologies characterized by negative affect, also providing a strong rationale for the application of bio-behavioral trainings

Human Amygdala in Sensory and Attentional Unawareness: Neural Pathways and Behavioural Outcomes

One of the neural structures more often implicated in the processing of emotional signals in the absence of visual awareness is the amygdala. In this chapter, we review current evidence from human neuroscience in healthy and brain-damaged patients on the role of amygdala during non-conscious (visual) perception of emotional stimuli. Nevertheless, there is as of yet no consensus on the limits and conditions that affect the extent of amygdala’s response without focused attention or awareness. We propose to distinguish between attentional unawareness, a condition wherein the stimulus is potentially accessible to enter visual awareness but fails to do so because attention is diverted, and sensory unawareness, in which the stimulus fails to enter awareness because its normal processing in the visual cortex is suppressed. Within this conceptual framework, some of the apparently contradictory findings seem to gain new coherence and converge on the role of the amygdala in supporting different types of non-conscious emotion processing. Amygdala responses in the absence of awareness are linked to different functional mechanisms and are driven by more complex neural networks than commonly assumed. Acknowledging this complexity can be helpful to foster new studies on amygdala functions without awareness and their impact on human behaviour

When is a face a face? Schematic faces, emotion, attention and the N170

Emotional facial expressions provide important non-verbal cues as to the imminent behavioural intentions of a second party. Hence, within emotion science the processing of faces (emotional or otherwise) has been at the forefront of research. Notably, however, such research has led to a number of debates including the ecological validity of utilising schematic faces in emotion research, and the face-selectively of N170. In order to investigate these issues, we explored the extent to which N170 is modulated by schematic faces, emotional expression and/or selective attention. Eighteen participants completed a three-stimulus oddball paradigm with two scrambled faces as the target and standard stimuli (counter-balanced across participants), and schematic angry, happy and neutral faces as the oddball stimuli. Results revealed that the magnitude of the N170 associated with the target stimulus was: (i) significantly greater than that elicited by the standard stimulus, (ii) comparable with the N170 elicited by the neutral and happy schematic face stimuli, and (iii) significantly reduced compared to the N170 elicited by the angry schematic face stimulus. These findings extend current literature by demonstrating N170 can be modulated by events other than those associated with structural face encoding; i.e. here, the act of labelling a stimulus a ‘target’ to attend to modulated the N170 response. Additionally, the observation that schematic faces demonstrate similar N170 responses to those recorded for real faces and, akin to real faces, angry schematic faces demonstrated heightened N170 responses, suggests caution should be taken before disregarding schematic facial stimuli in emotion processing research per se

The functional role of dreaming in emotional processes

Dream experience (DE) represents a fascinating condition linked to emotional processes and the human inner world. Although the overlap between REM sleep and dreaming has been overcome, several studies point out that emotional and perceptually vivid contents are more frequent when reported upon awakenings from this sleep stage. Actually, it is well-known that REM sleep plays a pivotal role in the processing of salient and emotional waking-life experiences, strongly contributing to the emotional memory consolidation. In this vein, we highlighted that, to some extent, neuroimaging studies showed that the processes that regulate dreaming and emotional salience in sleep mentation share similar neural substrates of those controlling emotions during wakefulness. Furthermore, the research on EEG correlates of the presence/absence of DE and the results on EEG pattern related to the incorporated memories converged to assign a crucial role of REM theta oscillations in emotional re-processing. In particular, the theta activity is involved in memory processes during REM sleep as well as during the waking state, in line with the continuity hypothesis. Also, the gamma activity seems to be related to emotional processes and dream recall as well as to lucid dreams. Interestingly, similar EEG correlates of DE have been found in clinical samples when nightmares or dreams occur. Research on clinical samples revealed that promoting the rehearsal of frightening contents aimed to change them is a promising method to treat nightmares, and that lucid dreams are associated with an attenuation of nightmares. In this view, DE can defuse emotional traumatic memories when the emotional regulation and the fear extinction mechanisms are compromised by traumatic and frightening events. Finally, dreams could represent a sort of simulation of reality, providing the possibility to create a new scenario with emotional mastery elements to cope with dysphoric items included in nightmares. In addition, it could be hypothesized that the insertion of bizarre items besides traumatic memories might be functional to “impoverish” the negative charge of the experiences