Martin Klasen

Supramodal representation of emotions

Supramodal representation of emotion and its neural substrates have recently attracted attention as a marker of social cognition. However, the question whether perceptual integration of facial and vocal emotions takes place in primary sensory areas, multimodal cortices, or in affective structures remains unanswered yet. Using novel computer-generated stimuli, we combined emotional faces and voices in congruent and incongruent ways and assessed functional brain data (fMRI) during an emotional classification task. Both congruent and incongruent audiovisual stimuli evoked larger responses in thalamus and superior temporal regions compared with unimodal conditions. Congruent emotions were characterized by activation in amygdala, insula, ventral posterior cingulate (vPCC), temporo-occipital, and auditory cortices; incongruent emotions activated a frontoparietal network and bilateral caudate nucleus, indicating a greater processing load in working memory and emotion-encoding areas. The vPCC alone exhibited differential reactions to congruency and incongruency for all emotion categories and can thus be considered a central structure for supramodal representation of complex emotional information. Moreover, the left amygdala reflected supramodal representation of happy stimuli. These findings document that emotional information does not merge at the perceptual audiovisual integration level in unimodal or multimodal areas, but in vPCC and amygdala.

Multisensory emotions: perception, combination and underlying neural processes

Abstract In our everyday lives, we perceive emotional information via multiple sensory channels. This is particularly evident for emotional faces and voices in a social context. Over the past years, a multitude of studies have addressed the question of how affective cues conveyed by auditory and visual channels are integrated. Behavioral studies show that hearing and seeing emotional expressions can support and influence each other, a notion which is supported by investigations on the underlying neurobiology. Numerous electrophysiological and neuroimaging studies have identified brain regions subserving the integration of multimodal emotions and have provided new insights into the neural processing steps underlying the synergistic confluence of affective information from voice and face. In this paper we provide a comprehensive review covering current behavioral, electrophysiological and functional neuroimaging findings on the combination of emotions from the auditory and visual domains. Behavioral advantages arising from multimodal redundancy are paralleled by specific integration patterns on the neural level, from encoding in early sensory cortices to late cognitive evaluation in higher association areas. In summary, these findings indicate that bimodal emotions interact at multiple stages of the audiovisual integration process.

Cognitive and neural strategies during control of the anterior cingulate cortex by fMRI neurofeedback in patients with schizophrenia

Cognitive functioning is impaired in patients with schizophrenia, leading to significant disabilities in everyday functioning. Its improvement is an important treatment target. Neurofeedback (NF) seems a promising method to address the neural dysfunctions underlying those cognitive impairments. The anterior cingulate cortex (ACC), a central hub for cognitive processing, is one of the brain regions known to be dysfunctional in schizophrenia. Here we conducted NF training based on real-time functional magnetic resonance imaging (fMRI) in patients with schizophrenia to enable them to control their ACC activity. Training was performed over 3 days in a group of 11 patients with schizophrenia and 11 healthy controls. Social feedback was provided in accordance with the evoked activity in the selected region of interest (ROI). Neural and cognitive strategies were examined off-line. Both groups learned to control the activity of their ACC but used different neural strategies: patients activated the dorsal and healthy controls the rostral subdivision. Patients mainly used imagination of music to elicit activity and the control group imagination of sports. In a stepwise regression analysis, the difference in neural control did not result from the differences in cognitive strategies but from diagnosis alone. Based on social reinforcers, patients with schizophrenia can learn to regulate localized brain activity. However, cognitive strategies and neural network location differ from healthy controls. These data emphasize that for therapeutic interventions in patients with schizophrenia compensatory strategies may emerge. Specific cognitive skills or specific dysfunctional networks should be addressed to train impaired skills. Social NF based on fMRI may be one method to accomplish precise learning targets.

Effects of serotonin depletion on punishment processing in the orbitofrontal and anterior cingulate cortices of healthy women

Diminished synthesis of the neurotransmitter serotonin (5-HT) has been linked to disrupted impulse control in aversive contexts. However, the neural correlates underlying a serotonergic modulation of female impulsivity remain unclear. The present study investigated punishment-induced inhibition in healthy young women. Eighteen healthy female subjects (aged 20-31) participated in a double-blinded, counterbalanced, placebo-controlled, within subjects, repeated measures study. They were assessed on two randomly assigned occasions that were controlled for menstrual cycle phase. In a randomized order, one day, acute tryptophan depletion (ATD) was used to reduce 5-HT synthesis in the brain. On the other day, participants received a tryptophan-balanced amino acid load (BAL) as a control condition. Three hours after administration of ATD/BAL, neural activity was recorded during a modified Go/No-Go task implementing reward or punishment processes using functional magnetic resonance imaging (fMRI). Neural activation during No-Go trials in punishment conditions after BAL versus ATD administration correlated positively with the magnitude of central 5-HT depletion in the ventral and subgenual anterior cingulate cortices (ACC). Furthermore, neural activation in the medial orbitofrontal cortex (mOFC) and the dorsal ACC correlated positively with trait impulsivity. The results indicate reduced neural sensitivity to punishment after short-term depletion of 5-HT in brain areas related to emotion regulation (subgenual ACC) increasing with depletion magnitude and in brain areas related to appraisal and expression of emotions (mOFC and dorsal ACC), increasing with trait impulsivity. This suggests a serotonergic modulation of neural circuits related to emotion regulation, impulsive behavior, and punishment processing in females.

Neural networks underlying affective states in a multimodal virtual environment: contributions to boredom

The interaction of low perceptual stimulation or goal-directed behavior with a negative subjective evaluation may lead to boredom. This contribution to boredom may shed light on its neural correlates, which are poorly characterized so far. A video game served as simulation of free interactive behavior without interruption of the game’s narrative. Thirteen male German volunteers played a first-person shooter game (Tactical Ops: Assault on Terror) during functional magnetic resonance imaging (fMRI). Two independent coders performed the time-based analysis of the audio-visual game content. Boredom was operationalized as interaction of prolonged absence of goal-directed behavior with lowered affect in the Positive and Negative Affect Schedule (PANAS). A decrease of positive affect (PA) correlated with response amplitudes in bilateral insular clusters extending into the amygdala to prolonged inactive phases in a game play and an increase in negative affect (NA) was associated with higher responses in bilateral ventromedial prefrontal cortex (vmPFC). Precuneus and hippocampus responses were negatively correlated with changes in NA. We describe for the first time neural contributions to boredom, using a video game as complex virtual environment. Further our study confirmed that PA and NA are separable constructs, reflected by distinct neural patterns. PA may be associated with afferent limbic activity whereas NA with affective control.

Quetiapine modulates functional connectivity in brain aggression networks

Aggressive behavior is associated with dysfunctions in an affective regulation network encompassing amygdala and prefrontal areas such as orbitofrontal (OFC), anterior cingulate (ACC), and dorsolateral prefrontal cortex (DLPFC). In particular, prefrontal regions have been postulated to control amygdala activity by inhibitory projections, and this process may be disrupted in aggressive individuals. The atypical antipsychotic quetiapine successfully attenuates aggressive behavior in various disorders; the underlying neural processes, however, are unknown. A strengthened functional coupling in the prefrontal-amygdala system may account for these anti-aggressive effects. An inhibition of this network has been reported for virtual aggression in violent video games as well. However, there have been so far no in-vivo observations of pharmacological influences on corticolimbic projections during human aggressive behavior. In a double-blind, placebo-controlled study, quetiapine and placebo were administered for three successive days prior to an fMRI experiment. In this experiment, functional brain connectivity was assessed during virtual aggressive behavior in a violent video game and an aggression-free control task in a non-violent modification. Quetiapine increased the functional connectivity of ACC and DLPFC with the amygdala during virtual aggression, whereas OFC-amygdala coupling was attenuated. These effects were observed neither for placebo nor for the non-violent control. These results demonstrate for the first time a pharmacological modification of aggression-related human brain networks in a naturalistic setting. The violence-specific modulation of prefrontal-amygdala networks appears to control aggressive behavior and provides a neurobiological model for the anti-aggressive effects of quetiapine.

Resting state default mode network connectivity in children and adolescents with ADHD after acute tryptophan depletion

Alterations of the default mode network (DMN) have been described in patients with neuropsychiatric disorders, including attention deficit hyperactivity disorder (ADHD), and the neurotransmitter serotonin (5‐HT) is known to modulate DMN activity. This study aimed to explore the role of 5‐HT on the DMN and its functional connectivity (FC) in young patients with ADHD.

Cortico-limbic connectivity in MAOA-L carriers is vulnerable to acute tryptophan depletion

A gene–environment interaction between expression genotypes of the monoamine oxidase A (MAOA) and adverse childhood experience increases the risk of antisocial behavior. However, the neural underpinnings of this interaction remain uninvestigated. A cortico‐limbic circuit involving the prefrontal cortex (PFC) and the amygdala is central to the suppression of aggressive impulses and is modulated by serotonin (5‐HT). MAOA genotypes may modulate the vulnerability of this circuit and increase the risk for emotion regulation deficits after specific life events. Acute tryptophan depletion (ATD) challenges 5‐HT regulation and may identify vulnerable neuronal circuits, contributing to the gene–environment interaction.

Neural processing of emotion in multimodal settings

Perhaps the most astonishing outcome of the Research Topic Neural processing of emotion in multimodal settings was the wide resonance. Not too long ago, emotions as well as multisensory integration both played outsider roles in neuroscience. However, nowadays the processing of emotional signals in the human brain has become an integrative part of basic neuroscience and clinical research. Considered a mere side effect of reasoning and thinking, the importance of emotions for human behavior has been underestimated for many years. The discovery of complex brain systems dedicated to the detection of harmful or positive situations, emotion recognition in others, and emotional experience have led to the conclusion that emotions are not at the periphery, but at the very core of human behavior. Among others, facial expressions, gestures, postures, and prosody express emotions. Thus, their integration is an essential part of face-to-face social interactions (De Gelder and Vroomen, 2000). Therefore, emotions have been described as inherently multimodal (Robins et al., 2009). This is also reflected on the psychological level, e.g., congruent bimodal emotions lead to shorter reaction times compared to faces alone (Massaro and Egan, 1996; Dolan et al., 2001).

Real-time noise cancellation for speech acquired in interactive functional magnetic resonance imaging studies.

To present online scanner noise cancellation for speech acquired in functional magnetic resonance imaging (fMRI) studies.