Belief updating during social interactions: neural dynamics and causal role of dorsomedial prefrontal cortex.

In competitive interactions, humans have to flexibly update their beliefs about another person's intentions in order to adjust their own choice strategy, such as when believing that the other may exploit their cooperativeness. Here we investigate both the neural dynamics and the causal neural substrate of belief updating processes in humans. We used an adapted prisoner's dilemma task in which participants explicitly predicted the co-player's actions, which allowed us to quantify the prediction error between expected and actual behaviour. First, in a EEG experiment we found a stronger medial frontal negativity (MFN) for negative than positive prediction errors, suggesting that this medial-frontal ERP component may encode unexpected defection of the co-player. The MFN also predicted subsequent belief updating after negative prediction errors. In a second experiment we used transcranial magnetic stimulation (TMS) to investigate whether the dorsomedial prefrontal cortex (dmPFC) causally implements belief updating after unexpected outcomes. Our results show that dmPFC TMS impaired belief updating and strategic behavioural adjustments after negative prediction errors. Taken together, our findings reveal the time-course of the use of prediction errors in social decisions, and suggest that the dmPFC plays a crucial role in updating mental representations of others' intentions.Significance statement For successful social interactions, humans must be able to reliably predict their interaction partners' actions. Previous research has linked this capacity mainly to posterior regions involved in mentalizing. Here, we show that the prefrontal cortex also plays a crucial role for adjusting our beliefs about others' cooperativeness as well: Inhibiting the dorsomedial prefrontal cortex with brain stimulation impaired the ability to modify expectations about the interaction partner's willingness to cooperate. Our findings highlight the role of belief updating for strategic social interactions, and identify the dorsomedial prefrontal cortex and its underlying neural dynamics as neural substrate of the ability to successfully learn others' strategies.

Freedom of choice boosts midfrontal theta power during affective feedback processing of goal-directed actions.

Sense of agency, the feeling of being in control of one's actions and their effects, is particularly relevant during goal-directed actions. During feedback learning, action effects provide information about the best course of action to reinforce positive and prevent negative outcomes. However, it is unclear whether agency experience selectively affects the processing of negative or positive feedback during the performance of goal-directed actions. As an important marker of feedback processing, we examined agency-related changes in midfrontal oscillatory activity in response to performance feedback using electroencephalography. Thirty-three participants completed a reinforcement learning task during which they received positive (monetary gain) or negative (monetary loss) feedback following item choices made either by themselves (free-choice) or by the computer (forced-choice). Independent of choice context, midfrontal theta activity was more enhanced for negative than positive feedback. In addition, free, compared to forced choices increased midfrontal theta power for both gain and loss feedback. These results indicate that freedom of choice in a motivationally salient learning task leads to a general enhancement in the processing of affective action outcomes. Our findings contribute to an understanding of the neuronal mechanisms underlying agency-related changes during action regulation and indicate midfrontal theta activity as a neurophysiological marker important for the monitoring of affective action outcomes, irrespective of feedback valence.

Flexible Changes in Attentional Focus and Task Rules Rely on A Shared Set of Frontoparietal Oscillatory Dynamics.

Flexible changes in behavior can involve changes in the processing of external information (i.e., shifts in attention between different stimuli) or internal information (i.e., shifts in task rules stored in memory). However, it is unclear if different types of flexible change rely on separate, domain-specific neural processes or on a domain-general system, which enables flexible actions independent of the type of change needed. In the current study, participants performed a task switching procedure while we measured neural oscillations via EEG. Importantly, we independently manipulated the need to switch attention between 2 types of stimuli, as well as the need to switch between two sets of stimuli-response rules stored in memory. Both attentional and rule switches significantly increased error rates and RTs. On a neural level, both types of changes were associated with a widespread decrease in alpha power, predominantly over the parietal cortex. Attentional switches and rule switches showed a subadditive interaction effect on both participants' performance as well as on their alpha power reactivity. This indicates that implementing both changes at the same time was more efficient than implementing each individual change separately. Independent of the presence or absence of either attentional or rule switches, higher frontal theta power and lower parietal/posterior alpha power predicted faster responses on correct trials. Our study suggests that flexible behavior relies on domain-general frontal and parietal oscillatory dynamics, which enable efficient implementation of goal-directed actions independent of which aspects of the task change.

Prepared to stop: how sense of agency in a preceding trial modulates inhibitory control in the current trial.

Feeling in control of actions and events can enhance motivation for further actions. How this sense of agency (SoA) in fact influences flexible motor control remains poorly understood. Here, we investigated the effect of SoA on subsequent response inhibition in a modified go/no-go task with EEG recordings. We manipulated participants' SoA by varying the presence, predictability, and emotional valence of a visual outcome for a given motor action. When participants unexpectedly did not receive any visible outcome following their action on trial n - 1, they exhibited slower responses and lower hit rates to the go signal but higher rates of successful inhibition to the no-go signal on trial n, regardless of the emotional valence of the expected action outcome. Furthermore, enhanced inhibitory tendencies were accompanied by reduced N2 and P3 amplitudes, midfrontal theta power, and theta synchronization between midfrontal and medial to parietal areas, indicating that less top-down control is required for successful response inhibition on trial n after experiencing low SoA on trial n - 1. These findings suggest that feeling less in control in a preceding trial makes it easier to implement inhibitory control in the current trial, thereby providing new insights into the role of SoA in goal-directed behavior.

Ready to go: Higher sense of agency enhances action readiness and reduces response inhibition.

Sense of agency is the subjective feeling of being in control of one's actions and their effects. Many studies have elucidated the cognitive and sensorimotor processes that drive this experience. However, less is known about how sense of agency influences flexible cognitive and motor control. Here, we investigated the effect of sense of agency on subsequent action regulation using a modified Go/No-Go task. In Experiment 1, we modulated participants' sense of agency by varying the occurrence of action outcomes (present vs. absent) both locally on a trial-by-trial basis and globally in terms of the overall probability of action outcomes within a block of trials (high vs. low). Importantly, we investigated how this manipulation influenced participants' responses to subsequent Go, No-Go, or Free-Choice cues. When participants' previous action led to an outcome (i.e., a happy face) compared with no outcome, they responded more accurately and faster to Go cues, reacted less accurately to No-Go cues, as well as made go decisions more frequently and faster to Free-Choice cues. These effects were even stronger when action outcomes occurred more frequently overall in a given block or in several previous trials. Experiment 2 further demonstrated that the effects of action outcome manipulation on subsequent action regulation were independent of the emotional valence of the action outcome (i.e., a happy or an angry face). Our results suggest that a higher sense of agency as induced by the presence of action outcomes enhanced action readiness and suppressed response inhibition. These findings highlight the impact of the control felt on the control used in action regulation, thereby providing new insights into the functional significance of the sense of agency on human behavior.

Function without feeling: neural reactivity and intercommunication during flexible motor adjustments evoked by emotional and neutral stimuli.

Motor conflicts arise when we need to quickly overwrite prepotent behavior. It has been proposed that affective stimuli modulate the neural processing of motor conflicts. However, previous studies have come to inconsistent conclusions regarding the neural impact of affective information on conflict processing. We employed functional magnetic resonance imaging during a Go/Change-Go task, where motor conflicts were either evoked by neutral or emotionally negative stimuli. Dynamic causal modeling was used to investigate how motor conflicts modulate the intercommunication between the anterior cingulate cortex (ACC) and the anterior insula (AI) as 2 central regions for cognitive control. Conflicts compared to standard actions were associated with increased BOLD activation in several brain areas, including the dorsal ACC and anterior insula. There were no differences in neural activity between emotional and non-emotional conflict stimuli. Conflicts compared to standard actions lowered neural self-inhibition of the ACC and AI and led to increased effective connectivity from the ACC to AI contralateral to the acting hand. Thus, our study indicates that neural conflict processing is primarily driven by the functional relevance of action-related stimuli, not their inherent affective meaning. Furthermore, it sheds light on the role of interconnectivity between ACC and AI for the implementation of flexible behavioral change.

Multisensory integration of anticipated cardiac signals with visual targets affects their detection among multiple visual stimuli.

Many studies have elucidated the multisensory processing of different exteroceptive signals (e.g., auditory-visual stimuli), but less is known about the multisensory integration of interoceptive signals with exteroceptive information. Here, we investigated the perceptual outcomes and electrophysiological brain mechanisms of cardio-visual integration by using participants' electrocardiogram signals to control the color change of a visual target in dynamically changing displays. Reaction times increased when the target change coincided with strong cardiac signals concerning the state of cardiovascular arousal (i.e., presented at the end of ventricular systole), compared to when the target change occurred at a time when cardiac arousal was relatively low (i.e., presented at the end of ventricular diastole). Moreover, the concurrence of the target change and cardiac arousal signals modulated the event-related potentials and the beta power in an early period (~100 ms after stimulus onset), and decreased the N2pc and the beta lateralization in a later period (~200 ms after stimulus onset). Our results suggest that the multisensory integration of anticipated cardiac signals with a visual target negatively affects its detection among multiple visual stimuli, potentially by suppressing sensory processing and reducing attention toward the visual target. This finding highlights the role of cardiac information in visual processing and furthers our understanding of the brain dynamics underlying multisensory perception involving both interoception and exteroception.

A Scalable Approach to Modeling on Accelerated Neuromorphic Hardware.

Neuromorphic systems open up opportunities to enlarge the explorative space for computational research. However, it is often challenging to unite efficiency and usability. This work presents the software aspects of this endeavor for the BrainScaleS-2 system, a hybrid accelerated neuromorphic hardware architecture based on physical modeling. We introduce key aspects of the BrainScaleS-2 Operating System: experiment workflow, API layering, software design, and platform operation. We present use cases to discuss and derive requirements for the software and showcase the implementation. The focus lies on novel system and software features such as multi-compartmental neurons, fast re-configuration for hardware-in-the-loop training, applications for the embedded processors, the non-spiking operation mode, interactive platform access, and sustainable hardware/software co-development. Finally, we discuss further developments in terms of hardware scale-up, system usability, and efficiency.

Response inhibition is disrupted by interoceptive processing at cardiac systole.

The present study investigated how cardiac signals influence response inhibition at both behavioral and electrophysiological levels by using participants' electrocardiogram signals to control the occurrence of events in a stop-signal task, in which the go cue was unpredictably followed by a stop signal requiring the cancellation of the prepotent response. We observed prolonged stop-signal reaction times, reduced stop-signal P3 amplitudes, and higher heartbeat evoked potential amplitudes when the stop signal was presented at cardiac systole, compared to presentation randomly within the cardiac cycle. These effects were independent of the emotional attribute of the stop signal (i.e., emotional facial expression change or non-emotional color change). Our results suggest that coupling stop signals to peripheral autonomic cardiac signals has an impeding effect on response inhibition, probably via shifting attention from exteroception to interoception. Our findings help clarify the precise impact of interoceptive signals on inhibitory control.

Preparing for Success: Neural Frontal Theta and Posterior Alpha Dynamics during Action Preparation Predict Flexible Resolution of Cognitive Conflicts.

Cognitive conflicts typically arise in situations that call for sudden changes in our behavior. Resolving cognitive conflicts is challenging and prone to errors. Humans can improve their chances to successfully resolve conflicts by mentally preparing for potential behavioral adjustments. Previous studies indicated that neural theta oscillations (4-7 Hz), as well as alpha oscillations (8-14 Hz), are reflective of cognitive control processes during conflict resolution. However, the role or neural oscillations for conflict preparation is still unclear. Therefore, the aim of the current study was to determine which oscillatory changes during conflict preparation predict subsequent resolution success. Participants performed a cued change-signal task, in which an anticipatory cue indicated if the upcoming trial might contain a cognitive conflict or not. Oscillatory activity was assessed via EEG. Cues that indicated that a conflict might arise compared with cues that indicated no conflict led to increases, directly followed by decreases, in theta power, as well as to decreases in alpha power. These cue-induced changes in theta and alpha oscillations occurred widespread across the cortex. Importantly, successful compared with failed conflict trials were characterized by selective increases in frontal theta power, as well as decreases in posterior alpha power during preparation. In addition, higher frontal theta power and lower posterior alpha power during preparation predicted faster conflict resolution. Our study shows that increases in frontal theta power, as well as decreases in posterior alpha power, are markers of optimal preparation for situations that necessitate flexible changes in behavior.

The BrainScaleS-2 Accelerated Neuromorphic System With Hybrid Plasticity.

Since the beginning of information processing by electronic components, the nervous system has served as a metaphor for the organization of computational primitives. Brain-inspired computing today encompasses a class of approaches ranging from using novel nano-devices for computation to research into large-scale neuromorphic architectures, such as TrueNorth, SpiNNaker, BrainScaleS, Tianjic, and Loihi. While implementation details differ, spiking neural networks-sometimes referred to as the third generation of neural networks-are the common abstraction used to model computation with such systems. Here we describe the second generation of the BrainScaleS neuromorphic architecture, emphasizing applications enabled by this architecture. It combines a custom analog accelerator core supporting the accelerated physical emulation of bio-inspired spiking neural network primitives with a tightly coupled digital processor and a digital event-routing network.

Emulating Dendritic Computing Paradigms on Analog Neuromorphic Hardware.

BrainScaleS-2 is an accelerated and highly configurable neuromorphic system with physical models of neurons and synapses. Beyond networks of spiking point neurons, it allows for the implementation of user-defined neuron morphologies. Both passive propagation of electric signals between compartments as well as dendritic spikes and plateau potentials can be emulated. In this paper, three multi-compartment neuron morphologies are chosen to demonstrate passive propagation of postsynaptic potentials, spatio-temporal coincidence detection of synaptic inputs in a dendritic branch, and the replication of the BAC burst firing mechanism found in layer 5 pyramidal neurons of the neocortex.

The Interplay Between Affective Processing and Sense of Agency During Action Regulation: A Review.

Sense of agency is the feeling of being in control of one's actions and their perceivable effects. Most previous research identified cognitive or sensory determinants of agency experience. However, it has been proposed that sense of agency is also bound to the processing of affective information. For example, during goal-directed actions or instrumental learning we often rely on positive feedback (e.g., rewards) or negative feedback (e.g., error messages) to determine our level of control over the current task. Nevertheless, we still lack a scientific model which adequately explains the relation between affective processing and sense of agency. In this article, we review current empirical findings on how affective information modulates agency experience, and, conversely, how sense of agency changes the processing of affective action outcomes. Furthermore, we discuss in how far agency-related changes in affective processing might influence the ability to enact cognitive control and action regulation during goal-directed behavior. A preliminary model is presented for describing the interplay between sense of agency, affective processing, and action regulation. We propose that affective processing could play a role in mediating the influence between subjective sense of agency and the objective ability to regulate one's behavior. Thus, determining the interrelation between affective processing and sense of agency will help us to understand the potential mechanistic basis of agency experience, as well as its functional significance for goal-directed behavior.

Motor Interference, But Not Sensory Interference, Increases Midfrontal Theta Activity and Brain Synchronization during Reactive Control.

Cognitive control helps us to overcome task interference in challenging situations. Resolving conflicts because of interfering influences is believed to rely on midfrontal theta oscillations. However, different sources of interference necessitate different types of control. Attentional control is needed to suppress salient distractors. Motor control is needed to suppress goal-incompatible action impulses. While previous studies mostly studied the additive effects of attentional and motor conflicts, we independently manipulated the need for attentional control (via visual distractors) and motor control (via unexpected response deviations) in an EEG study with male and female humans. We sought to find out whether these different types of control rely on the same midfrontal oscillatory mechanisms. Motor conflicts, but not attentional conflicts, elicited increases in midfrontal theta power during conflict resolution. Independent of the type of conflict, theta power was predictive of motor slowing. Connectivity analysis via phase-based synchronization indicated a widespread increase interbrain connectivity for motor conflicts, but a midfrontal-to-posterior decrease in connectivity for attentional conflicts. For each condition, we found stronger midfrontal connectivity with the parietal region contralateral to, rather than ipsilateral to, the acting hand. Parietal lateralization in connectivity was strongest for motor conflicts. Previous studies suggested that midfrontal theta oscillations might represent a general control mechanism, which aids conflict resolution independent of the conflict domain. In contrast, our results show that oscillatory theta dynamics during reactive control mostly reflect motor-related adjustments.SIGNIFICANCE STATEMENT Humans need to exercise self-control over both their attention (to avoid distraction) and their motor activity (to suppress inappropriate action impulses). Midfrontal theta oscillations have been assumed to indicate a general control mechanism, which help to exert top-down control during both motor and sensory interference. We are using a novel approach for the independent manipulation of attentional and motor control to show that increases in midfrontal theta power and brainwide connectivity are linked to the top-down adjustments of motor responses, not sensory interference. These findings clarify the function of midfrontal theta dynamics as a key aspect of neural top-down control and help to dissociate domain-general from motor-specific aspects of self-control.

Learning something new versus changing your ways: Distinct effects on midfrontal oscillations and cardiac activity for learning and flexible adjustments.

We need to be able to learn new behaviour, but also be capable of changing existing routines, when they start conflicting with our long-term goals. Little is known about to what extent blank-slate learning of new and adjustment of existing behavioural routines rely on different neural and bodily mechanisms. In the current study, participants first acquired novel stimulus-response contingencies, which were subsequently randomly changed to create the need for flexible adjustments. We measured midfrontal theta oscillations via EEG as an indicator of neural conflict processing, as well as heart rate as a proxy of autonomic activity. Participants' trial-wise learning progress was estimated via computation modelling. Theta power and heart rate significantly differed between correct and incorrect trials. Differences between correct and incorrect trials in both neural and cardiac feedback processing were more pronounced for adjustments compared to blank-slate learning. This indicates that both midfrontal and cardiac processing are sensitive to changes in stimulus-response contingencies. Increases in individual learning rates predicted lower impact of performance feedback on midfrontal theta power, but higher impact on heart rate. This suggests that cardiac and midfrontal reactivity are partially reflective of different mechanisms related to feedback learning. Our results shed new light on the role of neural and autonomic mechanisms for learning and behavioural adjustments.

Midfrontal neural dynamics distinguish between general control and inhibition-specific processes in the stopping of motor actions.

Action inhibition, the suppression of action impulses, is crucial for goal-directed behaviour. In order to dissociate neural mechanisms specific to motor stopping from general control processes which are also relevant for other types of conflict adjustments, we compared midfrontal oscillatory activity in human volunteers via EEG between action inhibition and two other types of motor conflicts, unexpected action activation and unexpected action change. Error rates indicated that action activation was significantly easier than the other two equally demanding tasks. Midfrontal brain oscillations were significantly stronger for inhibition than for both other conflict types. This was driven by increases in the delta range (2-3 Hz), which were higher for inhibition than activation and action change. Increases in the theta range (4-7 Hz) were equally high for inhibition and change, but lower for action activation. These findings suggest that inhibition is facilitated by neural mechanisms specific to motor-stopping, with midfrontal delta being a potentially selective marker of motor inhibition.

Proactive control without midfrontal control signals? The role of midfrontal oscillations in preparatory conflict adjustments.

Successful motor control during behavioral conflicts relies on neural adjustments that can occur reactively (i.e., after conflict occurrence) and proactively (i.e., in preparation prior to conflicts). While midfrontal delta/theta oscillations are known to play a role for reactive control, their relevance for proactive control is unclear. Using EEG, we investigated the role of midfrontal oscillations during conflict preparation in a motor conflict task, where a predictive cue either indicated no or an increased likelihood for an action conflict. During conflict preparation, increased conflict likelihood led to a proactive modulation of neural oscillations related to both motor processing (central beta) and sensory processing (posterior alpha). While midfrontal control oscillations significantly increased during conflict occurrence, increased conflict likelihood did not change midfrontal oscillatory activity during conflict preparation. This dissociation suggests that, while midfrontal oscillations are related to reactive conflict adjustments, proactive neural adjustment can be implemented without midfrontal oscillatory control.

Sensory attenuation of self-produced signals does not rely on self-specific motor predictions.

Sensory events produced by ourselves are known to lead to lower neural and perceptual impact than sensory events from other environmental sources. This sensory attenuation is widely assumed to result from control processes that are specific to our own motor actions, potentially helping us to distinguish effects produced by ourselves and others. However, previous research cannot rule out that the putative self-attenuation in fact reflect actor-independent, general predictive mechanisms, which, in direct comparison, just highlight external events due to lower predictability of their onset and thus higher surprise. By measuring the auditory-evoked N1 component, we show that self-generation of sounds only lead to cortical attenuation when the onset of other-generated sounds is less predictable due to the absence of any predictive cues. The presence of a cue predicting the onset of auditory stimuli, in contrast, led to a reversal of the attenuation effect, with lower N1 amplitudes for other-generated sounds in contrast to self-generated sounds. Thus, contrary to prevalent assumptions sensory attenuation is not bound to self-generation per se. Rather, it appears to be the result of general mechanisms that does not reliably and selectively attenuate self-induced stimulation but is determined by a flexible processing of sensory input based on its predictability, contextual relevance and attentional salience.

Assessing Psychological Fitness in the Military - Development of an Effective and Economic Screening Instrument.

Background: There are a high number of soldiers with deployment-related and non-deployment-related mental health problems in the German Armed Forces (Bundeswehr): This has led to an increase in mental disorders and a decrease in quality of life. To tackle these problems and to strengthen resources among the Bundeswehr personnel, this study aims at developing a screening instrument for assessing the psychological fitness of soldiers on the basis of questionnaire scales. In this approach, psychological fitness describes a soldier's ability to integrate and enhance his/her mental and emotional capabilities using resources and trainable skills. Methods: Bundeswehr combat soldiers (N = 361) answered questionnaires about resilience (RS-11), sense of coherence (SOC-L9), quality of life (WHOQOL-BREF), mental disorders (PHQ-D) and post-traumatic growth (PTG). Additionally, they were interviewed by trained troop psychologists both before and after their deployment in Afghanistan from January to June 2014. The screening model is based on self-report data; the psychological fitness in the standardized interview serves as a validation standard. Findings: A linear logistic regression model was performed that includes the social relationship and the psychological scale from WHOQOL-BREF and the somatoform and the stress scale from PHQ. This model allows specialists a first assessment between participants who are psychologically fit before and after deployment and those who are less so. The chosen cutoff for sensitivity is between 70% and 79% and for specificity between 70% and 85%. Discussion: This screening approach is still not applicable to large populations like that of the Bundeswehr, which currently has about 170,000 soldiers but it is limited to deployed combat troops. Classifying psychological fitness allows specialists to differentiate between people in need of special training or additional diagnostic measures and those in need of sustaining their fitness regularly at the earliest possible stage. A follow-up study that is representative of deployed and non-deployed military personnel will examine whether these results can be transferred to the entire Bundeswehr and whether the validity of the interview can be established.

The development of spontaneous facial responses to others' emotions in infancy: An EMG study.

Viewing facial expressions often evokes facial responses in the observer. These spontaneous facial reactions (SFRs) are believed to play an important role for social interactions. However, their developmental trajectory and the underlying neurocognitive mechanisms are still little understood. In the current study, 4- and 7-month old infants were presented with facial expressions of happiness, anger, and fear. Electromyography (EMG) was used to measure activation in muscles relevant for forming these expressions: zygomaticus major (smiling), corrugator supercilii (frowning), and frontalis (forehead raising). The results indicated no selective activation of the facial muscles for the expressions in 4-month-old infants. For 7-month-old infants, evidence for selective facial reactions was found especially for happy (leading to increased zygomaticus major activation) and fearful faces (leading to increased frontalis activation), while angry faces did not show a clear differential response. These results suggest that emotional SFRs may be the result of complex neurocognitive mechanisms which lead to partial mimicry but are also likely to be influenced by evaluative processes. Such mechanisms seem to undergo important developments at least until the second half of the first year of life.