Event-related microstate dynamics represents working memory performance.

In recent years, EEG microstate analysis has attracted much attention as a tool for characterizing the spatial and temporal dynamics of large-scale electrophysiological activities in the human brain. Canonical 4 states (classes A, B, C, and D) have been widely reported, and they have been pointed out for their relationships with cognitive functions and several psychiatric disorders such as schizophrenia, in particular, through their static parameters such as average duration, occurrence, coverage, and transition probability. However, the relationships between event-related microstate changes and their related cognitive functions, as is often analyzed in event-related potentials under time-locked frameworks, is still not well understood. Furthermore, not enough attention has been paid to the relationship between microstate dynamics and static characteristics. To clarify the relationships between the static microstate parameters and dynamic microstate changes, and between the dynamics and working memory (WM) function, we first examined the temporal profiles of the microstates during the N-back task. We found significant event-related microstate dynamics that differed predominantly with WM loads, which were not clearly observed in the static parameters. Furthermore, in the 2-back condition, patterns of state transitions from class A to C in the high- and low-performance groups showed prominent differences at 50-300 ms after stimulus onset. We also confirmed that the transition patterns of the specific time periods were able to predict the performance level (low or high) in the 2-back condition at a significant level, where a specific transition between microstates, namely from class A to C with specific polarity, contributed to the prediction robustly. Taken together, our findings indicate that event-related microstate dynamics at 50-300 ms after onset may be essential for WM function. This suggests that event-related microstate dynamics can reflect more highly-refined brain functions.

I Hear My Voice; Therefore I Spoke: The Sense of Agency Over Speech Is Enhanced by Hearing One's Own Voice.

The subjective experience of causing an action is known as the sense of agency. Dysfunctional sense of agency over speech has been suggested as a cause of auditory hallucinations. However, agency over speech has not been extensively characterized in previous empirical studies. Here, we manipulated self-voice identity, an indicator of self, embedded in the acoustic quality of voice and examined implicit and explicit measures of the sense of agency. Experiment 1 (N = 29 adults) demonstrated more compression of a perceived interval between action and outcome when participants heard their undistorted voices than their pitch-distorted voices. Experiment 2 (N = 28 adults) revealed a strong top-down effect of self-voice identity: Specifically, the judgment of agency over speech was more resistant than the judgment of agency over hand/limb movement to low-level sensorimotor inconsistency. Our findings provide new insight into the sense of agency over speech and an informative perspective for understanding aberrant experience in auditory hallucinations.

Real-Time Detection and Feedback of Canonical Electroencephalogram Microstates: Validating a Neurofeedback System as a Function of Delay.

Recent neurotechnology has developed various methods for neurofeedback (NF), in which participants observe their own neural activity to be regulated in an ideal direction. EEG-microstates (EEGms) are spatially featured states that can be regulated through NF training, given that they have recently been indicated as biomarkers for some disorders. The current study was conducted to develop an EEG-NF system for detecting "canonical 4 EEGms" in real time. There are four representative EEG states, regardless of the number of channels, preprocessing procedures, or participants. Accordingly, our 10 Hz NF system was implemented to detect them (msA, B, C, and D) and audio-visually inform participants of its detection. To validate the real-time effect of this system on participants' performance, the NF was intentionally delayed for participants to prevent their cognitive control in learning. Our results suggest that the feedback effect was observed only under the no-delay condition. The number of Hits increased significantly from the baseline period and increased from the 1- or 20-s delay conditions. In addition, when the Hits were compared among the msABCD, each cognitive or perceptual function could be characterized, though the correspondence between each microstate and psychological ability might not be that simple. For example, msD should be generally task-positive and less affected by the inserted delay, whereas msC is more delay-sensitive. In this study, we developed and validated a new EEGms-NF system as a function of delay. Although the participants were naive to the inserted delay, the real-time NF successfully increased their Hit performance, even within a single-day experiment, although target specificity remains unclear. Future research should examine long-term training effects using this NF system.

Sense of Agency Beyond Sensorimotor Process: Decoding Self-Other Action Attribution in the Human Brain.

The sense of agency is defined as the subjective experience that "I" am the one who is causing the action. Theoretical studies postulate that this subjective experience is developed through multistep processes extending from the sensorimotor to the cognitive level. However, it remains unclear how the brain processes such different levels of information and constitutes the neural substrates for the sense of agency. To answer this question, we combined two strategies: an experimental paradigm, in which self-agency gradually evolves according to sensorimotor experience, and a multivoxel pattern analysis. The combined strategies revealed that the sensorimotor, posterior parietal, anterior insula, and higher visual cortices contained information on self-other attribution during movement. In addition, we investigated whether the found regions showed a preference for self-other attribution or for sensorimotor information. As a result, the right supramarginal gyrus, a portion of the inferior parietal lobe (IPL), was found to be the most sensitive to self-other attribution among the found regions, while the bilateral precentral gyri and left IPL dominantly reflected sensorimotor information. Our results demonstrate that multiple brain regions are involved in the development of the sense of agency and that these show specific preferences for different levels of information.

Corrigendum: Touching! An Augmented Reality System for Unveiling Face Topography in Very Young Children.

[This corrects the article DOI: 10.3389/fnhum.2019.00189.].

Touching! An Augmented Reality System for Unveiling Face Topography in Very Young Children.

Developmental body topography, particularly of the face, is a fundamental research topic in the current decade. However, empirical investigation of this topic for very young children faces a number of difficulties related to the task requirements and technical procedures. In this study, we developed a new task to study the spatially-sensed position of facial parts in a self-face recognition task for 2.5- and 3.5-year-old children. Using the technique of augmented reality (AR) and 3D face tracking technology, we presented participants with their projected self-image on a screen, accompanied by a digital mark located on parts of their face. We prepared a cheerful visual and auditory reward on the screen when participants showed correct localization of the mark. We then tested whether they could indicate the position of the mark on their own faces and remain motivated for task repetition. To assess the efficacy of this task, 31 2.5- and 11 3.5-year-old children participated in this study. About half of the 2.5-year-olds and 80% of the 3.5-year-olds could perform more than 30 trials. Our new task, then, was to maintain young children's motivation for task repetition using the cheerful visual and auditory reward. The analysis of localization errors suggested the uniqueness of spatial knowledge of self-face in young children. The efficacy of this new task for studying the development of body image has been confirmed.

Measuring the sense of self in brain-damaged patients: A STROBE-compliant article.

Recently, researchers have focused on the embodied sense of self (ESS), which consists of the minimal and narrative selves. Although a study demonstrated that the ESS is related to brain dysfunction empirically, the subjective aspects of the ESS, and a systematic approach to it, have not yet been examined in brain-damaged patients. To examine this, we measured the ESS of patients with brain tumors before and after awake craniotomy.A self-reported questionnaire called the Embodied Sense of Self Scale (ESSS) was used to measure the ESS in patients with brain tumors before and after surgery. For comparison, age-matched controls also completed the ESSS.The ESSS scores of the patients with brain tumors before surgery were higher than those of the controls and improved after surgery. Before surgery, patients with left hemispheric lesions had a poorer ESSS than those with right hemispheric lesions. Episodic memory disturbance was highly correlated with malfunction of narrative self and ownership.Brain lesions were associated with anomalous ESSS, associated with hemispheric laterality and cognitive dysfunction.

Audio-tactile cues from an object's fall change estimates of one's body height.

When we drop an object from our hands, we use internal models of both our body height and object-motion to predict when it will hit the floor. What happens if the sensory feedback finally received from the impact conflicts with this prediction? The present study shows that such conflict results in changes in the internal estimates of our body height: When the object people dropped takes longer than expected to hit the floor, they report feeling taller and behave as if their legs were longer. This provides the first evidence of cross-modal recalibration of body-height representations as a function of changes in the distant environment. Crucially, the recalibration results from a mismatch between the predicted and actual outcome of an action, the ball's release and impact, which are causally-related but separated in space and time. These results suggest that implicit models of object-motion can interact with implicit and explicit models of one's body height.

Voluntarily controlled but not merely observed visual feedback affects postural sway.

Online stabilization of human standing posture utilizes multisensory afferences (e.g., vision). Whereas visual feedback of spontaneous postural sway can stabilize postural control especially when observers concentrate on their body and intend to minimize postural sway, the effect of intentional control of visual feedback on postural sway itself remains unclear. This study assessed quiet standing posture in healthy adults voluntarily controlling or merely observing visual feedback. The visual feedback (moving square) had either low or high gain and was either horizontally flipped or not. Participants in the voluntary-control group were instructed to minimize their postural sway while voluntarily controlling visual feedback, whereas those in the observation group were instructed to minimize their postural sway while merely observing visual feedback. As a result, magnified and flipped visual feedback increased postural sway only in the voluntary-control group. Furthermore, regardless of the instructions and feedback manipulations, the experienced sense of control over visual feedback positively correlated with the magnitude of postural sway. We suggest that voluntarily controlled, but not merely observed, visual feedback is incorporated into the feedback control system for posture and begins to affect postural sway.

Individual differences and the effect of face configuration information in the McGurk effect.

The McGurk effect, which denotes the influence of visual information on audiovisual speech perception, is less frequently observed in individuals with autism spectrum disorder (ASD) compared to those without it; the reason for this remains unclear. Several studies have suggested that facial configuration context might play a role in this difference. More specifically, people with ASD show a local processing bias for faces-that is, they process global face information to a lesser extent. This study examined the role of facial configuration context in the McGurk effect in 46 healthy students. Adopting an analogue approach using the Autism-Spectrum Quotient (AQ), we sought to determine whether this facial configuration context is crucial to previously observed reductions in the McGurk effect in people with ASD. Lip-reading and audiovisual syllable identification tasks were assessed via presentation of upright normal, inverted normal, upright Thatcher-type, and inverted Thatcher-type faces. When the Thatcher-type face was presented, perceivers were found to be sensitive to the misoriented facial characteristics, causing them to perceive a weaker McGurk effect than when the normal face was presented (this is known as the McThatcher effect). Additionally, the McGurk effect was weaker in individuals with high AQ scores than in those with low AQ scores in the incongruent audiovisual condition, regardless of their ability to read lips or process facial configuration contexts. Our findings, therefore, do not support the assumption that individuals with ASD show a weaker McGurk effect due to a difficulty in processing facial configuration context.

Agency over Phantom Limb Enhanced by Short-Term Mirror Therapy.

Most amputees experience phantom limb, whereby they feel that the amputated limb is still present. In some cases, these experiences include pain that can be alleviated by "mirror therapy." Mirror therapy consists of superimposing a mirrored image of the moving intact limb onto the phantom limb. This therapy provides a closed loop between the motor command to the amputated limb and its predicted visual feedback. This loop is also involved in the sense of agency, a feeling of controlling one's own body. However, it is unclear how mirror therapy is related to the sense of agency over a phantom limb. Using mirror therapy, we investigated phantom limb pain and the senses of agency and ownership (i.e., a feeling of having one's own body) of the phantom limb. Nine upper-limb amputees, five of whom reported recent phantom limb pain, underwent a single 15-min trial of mirror therapy. Before and after the trial, the participants completed a questionnaire regarding agency, ownership, and pain related to their phantom limb. They reported that the sense of agency over the phantom limb increased following the mirror therapy trial, while the ownership slightly increased but not as much as did the agency. The reported pain did not change; that is, it was comparably mild before and after the trial. These results suggest that short-term mirror therapy can, at least transiently, selectively enhance the sense of agency over a phantom limb, but may not alleviate phantom limb pain.

Subjectivity of the Anomalous Sense of Self Is Represented in Gray Matter Volume in the Brain.

The self includes complicated and heterogeneous functions. Researchers have divided the self into three distinct functions called "agency," "ownership," and "narrative self". These correspond to psychiatric symptoms, behavioral characteristics and neural responses, but their relationship with brain structure is unclear. This study examined the relationship between the subjectivity of self-related malfunctions and brain structure in terms of gray matter (GM) volume in 96 healthy people. They completed a recently developed self-reported questionnaire called the Embodied Sense of Self Scale (ESSS) that measures self-related malfunctions. The ESSS has three subscales reflecting the three distinct functions of the self. We also determined the participants' brain structures using magnetic resonance imaging (MRI) and voxel-based morphometry (VBM). Multiple regression analysis revealed a significant negative correlation between ownership malfunction and the insular cortex GM volume. A relationship with brain structure could thus only be confirmed for the ESSS "ownership" subscale. This finding suggests that distinct brain structures feel ownership and that the ESSS could partly screen for distinct brain structures.

My action lasts longer: Potential link between subjective time and agency during voluntary action.

Time perception distorts across different phases of bodily movement. During motor execution, sensory feedback matching an internal sensorimotor prediction is perceived to last longer. The sensorimotor prediction also underlies sense of agency. We investigated association between subjective time and agency during voluntary action. Participants performed hand action while watching a video feedback of their hand with various delays to manipulate agency. The perceived duration and agency over the video feedback were judged. Minimal delay of the video feedback resulted in longer perceived duration than the actual duration and stronger agency, while substantial feedback delay resulted in shorter perceived duration and weaker agency. These fluctuations of perceived duration and agency were nullified by the feedback of other's hand instead of their own, but not by inverted feedback from a third-person perspective. Subjective time during action might be associated with agency stemming from sensorimotor prediction, and self-other distinction based on bodily appearance.

Know thy agency in predictive coding: Meta-monitoring over forward modeling.

Though the computation of agency is thought to be based on prediction error, it is important for us to grasp our own reliability of that detected error. Here, the current study shows that we have a meta-monitoring ability over our own forward model, where the accuracy of motor prediction and therefore of the felt agency are implicitly evaluated. Healthy participants (N=105) conducted a simple motor control task and SELF or OTHER visual feedback was given. The relationship between the accuracy and confidence in a mismatch detection task and in a self-other attribution task was examined. The results suggest an accuracy-confidence correlation in both tasks, indicating our meta-monitoring ability over such decisions. Furthermore, a statistically identified group with low accuracy and low confidence was characterized as higher schizotypal people. Finally, what we can know about our own forward model and how we can know it is discussed.

Auditory multistability and neurotransmitter concentrations in the human brain.

Multistability in perception is a powerful tool for investigating sensory-perceptual transformations, because it produces dissociations between sensory inputs and subjective experience. Spontaneous switching between different perceptual objects occurs during prolonged listening to a sound sequence of tone triplets or repeated words (termed auditory streaming and verbal transformations, respectively). We used these examples of auditory multistability to examine to what extent neurochemical and cognitive factors influence the observed idiosyncratic patterns of switching between perceptual objects. The concentrations of glutamate-glutamine (Glx) and γ-aminobutyric acid (GABA) in brain regions were measured by magnetic resonance spectroscopy, while personality traits and executive functions were assessed using questionnaires and response inhibition tasks. Idiosyncratic patterns of perceptual switching in the two multistable stimulus configurations were identified using a multidimensional scaling (MDS) analysis. Intriguingly, although switching patterns within each individual differed between auditory streaming and verbal transformations, similar MDS dimensions were extracted separately from the two datasets. Individual switching patterns were significantly correlated with Glx and GABA concentrations in auditory cortex and inferior frontal cortex but not with the personality traits and executive functions. Our results suggest that auditory perceptual organization depends on the balance between neural excitation and inhibition in different brain regions.This article is part of the themed issue 'Auditory and visual scene analysis'.

Self is "other", other is "self": poor self-other discriminability explains schizotypal twisted agency judgment.

Anomalous agency has been reported clinically and empirically for people with schizophrenia. This finding is expected to contribute to understanding positive symptomatology in schizophrenia in terms of a general neurocomputational model of motor control, because anomalous agency has also been reported in schizotypal traits in the general population. However, superficially opposite conclusions have been suggested: over-attributed or under-attributed agency in patients. In this work, healthy participants (N=104) were presented continuous morphed self-other visual feedback of their reaching movements and rated the agency they felt for it. The slope of the regression line in stimuli-response coordination as a function of self-other discriminability was estimated for each participant. The estimated slopes were significantly associated with positive schizotypal symptomatology. Higher schizotypal participants exhibited a lower slope, indicating poorer discriminability between their own and others' movements. Furthermore, the estimated regression lines in the high and low groups are predicted to cross at the approximately center point in the coordinates, which should produce both over-attribution and under-attribution errors for the high group compared with low group. The pattern of schizotypal attribution error depends on the S/N (signal-to-noise) ratio of the given stimuli within our sensorimotor system where the self-originated stimulus is the signal to be detected. The current study, for the first time, suggests both over- and under-attribution within participants scoring high on schizotypy.

Embodied prosthetic arm stabilizes body posture, while unembodied one perturbs it.

Senses of ownership (this arm belongs to me) and agency (I am controlling this arm) originate from sensorimotor system. External objects can be integrated into the sensorimotor system following long-term use, and recognized as one's own body. We examined how an (un)embodied prosthetic arm modulates whole-body control, and assessed the components of prosthetic embodiment. Nine unilateral upper-limb amputees participated. Four frequently used their prosthetic arm, while the others rarely did. Their postural sway was measured during quiet standing with or without their prosthesis. The frequent users showed greater sway when they removed the prosthesis, while the rare users showed greater sway when they fitted the prosthesis. Frequent users reported greater everyday feelings of postural stabilization by prosthesis and a larger sense of agency over the prosthesis. We suggest that a prosthetic arm maintains or perturbs postural control, depending on the prosthetic embodiment, which involves sense of agency rather than ownership.

Development of Embodied Sense of Self Scale (ESSS): Exploring Everyday Experiences Induced by Anomalous Self-Representation.

The scientific exploration of the self has progressed, with much attention focused on the Embodied Sense of Self (ESS). Empirical studies have suggested the mechanisms for self-representation. On the other hand, less attention has been paid to the subjectivity itself of the self. With reference to previous studies, the current study collected items that reflect the ESS and statistically extracted three factors for it: Ownership, Agency, and Narrative. The developed questionnaire [Embodied Sense of Self Scale (ESSS)] showed good enough validity and reliability for practical use. Furthermore, ESSS discriminated schizophrenia, a disorder of the ESS, from controls. We discuss the factorial structure of ESS and the relationship among factors on the basis of the current results.

Computational motor control as a window to understanding schizophrenia.

In addition to mental disorders such as attention, emotion, delusions, hallucinations, and difficulties in social skills, the patients with schizophrenia exhibits significant abnormality in sensorimotor perception and control. To seek a neurobiological cause of the heterogeneous symptoms in schizophrenia, we focused on the impaired inference mechanism of the self-agency of the schizophrenia's brain where the sensory outcome generated by the self-initiated action was misattributed to the other agent's action. By developing a novel computational model of agency experience using a Bayesian decision making framework, we united the computational mechanisms of agency and motor control via internal model: a model for one to predict the sensory consequence of action. Our theory based on optimal feedback control with Kalman filtering successfully predicted a variety of schizophrenia's motor abnormalities assuming a deformed internal model. To discuss the plausibility of these model predictions, we reviewed literature that might support these predictions. We further proposed some experiments that potentially examine the proposed model of schizophrenia. Our approach in investigating a problem of mind by projecting it on the coordinates system of the embodiment effectively shed light on a central neuropathology of this disease that had been latent behind the observed behaviors.

Agency elicits body-ownership: proprioceptive drift toward a synchronously acting external proxy.

Awareness of our own bodies (sense of body-ownership) and actions (sense of agency) is fundamental for self-consciousness. In the rubber hand illusion, watching a rubber hand being stroked synchronously as one's own unseen hand is also stroked causes the observer to attribute the rubber hand to their own body. The findings of the series of experiments reported here suggest that body-ownership, measured using proprioceptive drift, is elicited by the external acting proxy that drives the sense of agency. While participants clasped and unclasped their left hand for 60 s, they focused on video feedback on a monitor in front of them. Proprioceptive drift was observed only under the conditions, including synchronized conditions, where the sense of agency for the acting proxy occurred, suggesting an essential interaction between body-ownership and agency.