Feel the Time. Time Perception as a Function of Interoceptive Processing

Modality-specific effects of threat on self-motion perception

BACKGROUND

Threat and individual differences in threat-processing bias perception of stimuli in the environment. Yet, their effect on perception of one's own (body-based) self-motion in space is unknown. Here, we tested the effects of threat on self-motion perception using a multisensory motion simulator with concurrent threatening or neutral auditory stimuli.

RESULTS

Strikingly, threat had opposite effects on vestibular and visual self-motion perception, leading to overestimation of vestibular, but underestimation of visual self-motions. Trait anxiety tended to be associated with an enhanced effect of threat on estimates of self-motion for both modalities.

CONCLUSIONS

Enhanced vestibular perception under threat might stem from shared neural substrates with emotional processing, whereas diminished visual self-motion perception may indicate that a threatening stimulus diverts attention away from optic flow integration. Thus, threat induces modality-specific biases in everyday experiences of self-motion.

Attention to cardiac sensations enhances the heartbeat-evoked potential during exhalation

Respiration and cardiac activity intricately interact through complex physiological mechanisms. The heartbeat-evoked potential (HEP) is an EEG fluctuation reflecting the cortical processing of cardiac signals. We recently found higher HEP amplitude during exhalation than inhalation during a task involving attention to cardiac sensations. This may have been due to reduced cardiac perception during inhalation and heightened perception during exhalation through attentional mechanisms. To investigate relationships between HEP, attention, and respiration, we introduced an experimental setup that included tasks related to cardiac and respiratory interoceptive and exteroceptive attention. Results revealed HEP amplitude increases during the interoceptive tasks over fronto-central electrodes. When respiratory phases were taken into account, HEP increases were primarily driven by heartbeats recorded during exhalation, specifically during the cardiac interoceptive task, while inhalation had minimal impact. These findings emphasize the role of respiration in cardiac interoceptive attention and could have implications for respiratory interventions to fine-tune cardiac interoception.

Interoceptive technologies for psychiatric interventions: From diagnosis to clinical applications

Interoception-the perception of internal bodily signals-has emerged as an area of interest due to its implications in emotion and the prevalence of dysfunctional interoceptive processes across psychopathological conditions. Despite the importance of interoception in cognitive neuroscience and psychiatry, its experimental manipulation remains technically challenging. This is due to the invasive nature of existing methods, the limitation of self-report and unimodal measures of interoception, and the absence of standardized approaches across disparate fields. This article integrates diverse research efforts from psychology, physiology, psychiatry, and engineering to address this oversight. Following a general introduction to the neurophysiology of interoception as hierarchical predictive processing, we review the existing paradigms for manipulating interoception (e.g., interoceptive modulation), their underlying mechanisms (e.g., interoceptive conditioning), and clinical applications (e.g., interoceptive exposure). We suggest a classification for interoceptive technologies and discuss their potential for diagnosing and treating mental health disorders. Despite promising results, considerable work is still needed to develop standardized, validated measures of interoceptive function across domains and before these technologies can translate safely and effectively to clinical settings.

Creating critical palliative hypnotic adjustments: temporality, hope, and meaning

When cure is not possible, suffering often takes form as pain and distressing symptoms, death anxiety, existential distress, and meaninglessness. This paper describes important elements connecting palliative care principles with hypnotic approaches designed to provide support, palliate symptoms, foster hope, and address existential and spiritual distress. We offer a developmental process for and examples of hypnotic suggestions customized to simultaneously ameliorate physical symptoms and address profound distress arising from physical, social, psychological, existential, and spiritual challenges commonly encountered in terminal illness. This process necessarily requires use of the patient's vernacular to hypnotically deepen inwardly focused attention in order to explore and access internal resources, reframe negative automatic thoughts, and create positive meanings for experiences that disinvite suffering. Effective delivery utilizes cognitive tools such as clinical and scientific principles, artistic forms such as poetry and haiku, and a thorough assessment of needs. This approach strategically addresses an overarching dimension of temporality through suggestions that sequentially address multiple sources of suffering that are layered throughout the various dimensions of self. This requires focus and presence in the present moment; it ultimately fosters a therapeutic relationship that can safely hold past painful experience as helpful new meanings emerge that build resiliency for that experience. This work benefits from inwardly focused concentration and a holding environment to identify and access helpful inner resources, which include an increasingly malleable relationship with temporal memories.

Effect of subconscious changes in bodily response on thought shifting in people with accurate interoception

Our thought states shift from one state to another from moment to moment. The relationship between the thought shifting and bodily responses is yet to be directly examined. This exploratory study examined the influence of cardiovascular reactivity and interoception-sensing an internal bodily state-on the shifting of thought states. Participants (N = 100, 70 women) completed two tasks: the heartbeat counting task (HCT) and the vigilance task (VT). We assessed their interoceptive accuracy through their performance on the HCT. The VT was a simple sustained attention task in which participants pressed a key when the target stimulus appeared and were asked to report their thoughts. We presented subliminal vibration stimuli to induce alterations in heart rate (i.e., vibration block). Results showed that participants with higher interoceptive accuracy reported more continuation of self-referential thought (about past episodes and future plans regarding themselves) during the vibration block than did those with lower interoceptive accuracy. These results suggest that individuals with higher interoceptive accuracy are more likely to be influenced by their subliminal bodily response, resulting in divergent attention from the task and intermittent self-referential thought.

Validating virtual reality for time perception research: Virtual reality changes expectations about the duration of physical processes, but not the sense of time

Immersive virtual reality (VR) provides a versatile method for investigating human time perception, because it allows the manipulation and control of relevant variables (e.g., the speed of environmental changes) that cannot be modified in the real world. However, an important premise for interpreting the results of VR studies, namely that the method itself does not affect time perception, has received little attention. Here we tested this assumption by comparing timing performance in a real environment and a VR scenario. Participants performed two timing tasks, requiring the production of intervals defined either by numerical values ("eight seconds") or by a physical process ("the time it takes for a bottle to run out when turned over"). We found that the experience of immersive VR exclusively altered judgments about the duration of physical processes, whereas judgments about the duration of abstract time units were unaffected. These results demonstrate that effects of VR on timing performance are not driven by changes in time perception itself, but rather by altered expectations regarding the duration of physical processes. The present study validates the use of VR in time perception research and strengthens the interpretation of changed timing behaviour induced by manipulations within VR.

Time perception and pain: Can a temporal illusion reduce the intensity of pain?

It is commonly known-and previous studies have indicated-that time appears to last longer during unpleasant situations. This study examined whether a reciprocal statement can be made-that is, whether changes in the perception of time can influence our judgment (or rating) of a negative event. We used a temporal illusion method (Pomares et al. Pain 152, 230-234, 2011) to induce distortions in the perception of time. Two stimuli were presented for a constant time: a full clock, which stayed on the screen until its clock hand completed a full rotation (360°); and a short clock, in which the clock hand moved just three-quarters of the way (270°), thus suggesting a reduced interval duration. However, both stimuli were shown for the same amount of time. We specifically investigated (a) whether we could induce a temporal illusion with this simple visual manipulation, and (b) whether this illusion could change participants' ratings of a painful stimulus. In Experiment I (n = 22), to answer (a) above, participants were asked to reproduce the duration in which the different clocks were presented. In Experiment II (n = 30), a painful thermal stimulation was applied on participants' hands while the clocks were shown. Participants were asked to rate the perceived intensity of their pain, and to reproduce its duration. Results showed that, for both experiments, participants reproduced a longer interval after watching the full clock compared with the short clock, confirming that the clock manipulation was able to induce a temporal illusion. Furthermore, the second experiment showed that participants rated the thermal stimuli as less painful when delivered with the short clock than with the full clock. These findings suggest that temporal distortions can modulate the experience of pain.

Effect of the number and diversity of visual stimuli on the reproduction of short time intervals

Presenting more items within a space makes the space look and feel bigger. Presenting more tones within a time interval makes the interval seem longer. Does presenting more visual items also make a time interval seem longer? Does it matter what these items are? A series of 2-4 images were presented sequentially on a screen. Participants had to press the spacebar to indicate either the interval between the first and the last item or the intervals between all items. The first and last items were red squares with onset asynchronies of 700, 900, or 1,100 ms. We found that the times between key presses were longer when additional items had different shapes and colors than when they were also red squares. With only red squares, the time may even decrease with the number of items. Whether one had to tap for all targets or only the first and the last hardly mattered.

Time distortions induced by high-arousing emotional compared to low-arousing neutral faces: an event-related potential study

Emotions influence our perception of time. Arousal and valence are considered different dimensions of emotions that might interactively affect the perception of time. In the present study, we aimed to investigate the possible time distortions induced by emotional (happy/angry) high-arousing faces compared to neutral, low-arousing faces. Previous works suggested that emotional stimuli enhance the amplitudes of several posterior components, such as Early Posterior Negativity (EPN) and Late Positive Potential (LPP). These components reflect several stages of emotional processing. To this end, we conducted an event-related potential (ERP) study with a temporal bisection task. We hypothesized that the partial dissociation of these ERP components would shed more light on the possible relations of valence and arousal on emotional facial regulation and their consequential effects on behavioral timing. The behavioral results demonstrated a significant effect for emotional stimuli, as happy faces were overestimated relative to angry faces. Our results also indicated higher temporal sensitivity for angry faces. The analyzed components (EPN and LLP) provided further insights into the qualitative differences between stimuli. Finally, the results were interpreted considering the internal clock model and two-stage processing of emotional stimuli.

Time perception at resting state and during active motion: The role of anxiety and depression

BACKGROUND

Time perception and motion intensity are interrelated factors that may influence symptom expression and severity in case of various psychiatric conditions, including anxiety and depression.

AIMS

The present study aimed to 1) explore the associations between the intensity of physical activity, time perception, impulsivity, anxiety and depressive symptoms, and to 2) investigate the extent to which resting state motion intensity can be used to identify the assessed psychiatric conditions.

METHODS

20 healthy controls and 20 psychiatric patients (with either anxiety or depression-related diagnoses) were included in the study and filled out a questionnaire consisting of validated anxiety, depression and impulsivity measures. Time perception was measured by a computerized time production task, whereas motion intensity was analyzed by a motion capture and analysis software. Respondents were randomly assigned to an experimental (with active motion task) and non-experimental group (resting state conditions). Both subgroups were repeatedly assessed, in order to explore changes in motion intensity, time perception and psychiatric symptom levels.

RESULTS

Random forest regression analysis identified the level of impulsivity, depression and anxiety as the strongest predictors of resting state motion intensity, while a path analysis model indicated that controls and psychiatric patients show different pathways regarding the connection between motion intensity changes, time production ratio alterations and symptom reduction.

CONCLUSIONS

Our study implies the importance of distinguishing between clinical and subclinical severity of psychiatric symptoms when considering the association between motion intensity, time perception, anxiety and depression. Potential transdiagnostic relevance of resting state motion intensity is also addressed.

How Does Emotion Influence Time Perception? A Review of Evidence Linking Emotional Motivation and Time Processing

Emotions have a strong influence on how we experience time passing. The body of research investigating the role of emotion on time perception has steadily increased in the past twenty years. Several affective mechanisms have been proposed to influence the passing of time. The current review focuses on how three dimensions of affect-valence, arousal, and motivation-are related to time perception. The valence-based model of time perception predicts that all positive affects hasten the perception of time and all negative affects slow the perception of time. Arousal is thought to intensify the effects of the influence of valence on time perception. In much of this past work, motivational direction has been confounded with valence, whereas motivational intensity has been confounded with arousal. Research investigating the role of motivation in time perception has found that approach-motivated positive and negative affects hasten the perception of time, but withdrawal-motivated affects slow the perception of time. Perceiving time passing quickly while experiencing approach-motivated states may provide significant advantages related to goal pursuit. In contrast, perceiving time passing slowly while experiencing withdrawal-motivated states may increase avoidance actions. Below, we review evidence supporting that approach motivation hastens the passing of time, whereas withdrawal motivation slows the passing of time. These results suggest that motivational direction, rather than affective valence and arousal, drive emotional changes in time perception.

A Neuroscientific and Cognitive Literary Approach to the Treatment of Time in Calderón's Autos sacramentales

Time processing is a fundamental subject in cognitive sciences and neuroscience. Current research is deepening how our brains process time, revealing its essential role in human functionality and survival. In his autos sacramentales, Early Modern Spanish playwright Pedro Calderón de la Barca portrays the relationships between human inner workings and the Christian concept of time. These plays portray the experience of the present, the perception of the flow of time, the measure of time raging from seconds to eternity, and the mental travel necessary to inhabit the past and future with the help of memory and imagination. Calderón explores how the dramatic form can portray all these temporal phenomena and how that portrait of time can constrain the dramatic structure. The different parts of the brain in charge of executive decisions, projections, memories, computation, and calibration are the basis that leads these characters to make the choices that will take them to the future they have cast for themselves. This paper analyzes how the processes that Calderón ascribed to the soul of his characters in the 17th century relate to ongoing cognitive and neuroscientific findings.

At the Heart of Neurological Dimensionality: Cross-Nosological and Multimodal Cardiac Interoceptive Deficits

OBJECTIVE

Neurological nosology, based on categorical systems, has largely ignored dimensional aspects of neurocognitive impairments. Transdiagnostic dimensional approaches of interoception (the sensing of visceral signals) may improve the descriptions of cross-pathological symptoms at behavioral, electrophysiological, and anatomical levels. Alterations of cardiac interoception (encompassing multidimensional variables such as accuracy, learning, sensibility, and awareness) and its neural correlates (electrophysiological markers, imaging-based anatomical and functional connectivity) have been proposed as critical across disparate neurological disorders. However, no study has examined the specific impact of neural (relative to autonomic) disturbances of cardiac interoception or their differential manifestations across neurological conditions.

METHODS

Here, we used a computational approach to classify and evaluate which markers of cardiac interoception (behavioral, metacognitive, electrophysiological, volumetric, or functional) offer the best discrimination between neurological conditions and cardiac (hypertensive) disease (model 1), and among neurological conditions (Alzheimer's disease, frontotemporal dementia, multiple sclerosis, and brain stroke; model 2). In total, the study comprised 52 neurological patients (mean [standard deviation] age = 55.1 [17.3] years; 37 women), 25 cardiac patients (age = 66.2 [9.1] years; 13 women), and 72 healthy controls (age = 52.65 [17.1] years; 50 women).

RESULTS

Cardiac interoceptive outcomes successfully classified between neurological and cardiac conditions (model 1: >80% accuracy) but not among neurological conditions (model 2: 53% accuracy). Behavioral cardiac interoceptive alterations, although present in all conditions, were powerful in differentiating between neurological and cardiac diseases. However, among neurological conditions, cardiac interoceptive deficits presented more undifferentiated and unspecific disturbances across dimensions.

CONCLUSIONS

Our result suggests a diffuse pattern of interoceptive alterations across neurological conditions, highlighting their potential role as dimensional, transdiagnostic markers.

The Emerging Science of Interoception: Sensing, Integrating, Interpreting, and Regulating Signals within the Self

Interoception refers to the representation of the internal states of an organism, and includes the processes by which it senses, interprets, integrates, and regulates signals from within itself. This review presents a unified research framework and attempts to offer definitions for key terms to describe the processes involved in interoception. We elaborate on these definitions through illustrative research findings, and provide brief overviews of central aspects of interoception, including the anatomy and function of neural and non-neural pathways, diseases and disorders, manipulations and interventions, and predictive modeling. We conclude with discussions about major research gaps and challenges.

Presence, flow, and narrative absorption: an interdisciplinary theoretical exploration with a new spatiotemporal integrated model based on predictive processing

Presence, flow, narrative absorption, immersion, transportation, and similar subjective phenomena are studied in many different disciplines, mostly in relation to mediated experiences (books, film, VR, games). Moreover, since real, virtual, or fictional agents are often involved, concepts like identification and state empathy are often linked to engaging media use. Based on a scoping review that identified similarities in the wording of various questionnaire items conceived to measure different phenomena, we categorize items into the most relevant psychological aspects and use this categorization to propose an interdisciplinary systematization. Then, based on a framework of embodied predictive processing, we present a new cognitive model of presence-related phenomena for mediated and non-mediated experiences, integrating spatial and temporal aspects and also considering the role of fiction and media design. Key processes described within the model are: selective attention, enactment of intentions, and interoception. We claim that presence is the state of perceived successful agency of an embodied mind able to correctly enact its predictions. The difference between real-life and simulated experiences ("book problem," "paradox of fiction") lays in the different precision weighting of exteroceptive and interoceptive signals.

Virtual Body Ownership Illusions for Mental Health: A Narrative Review

Over the last 20 years, virtual reality (VR) has been widely used to promote mental health in populations presenting different clinical conditions. Mental health does not refer only to the absence of psychiatric disorders but to the absence of a wide range of clinical conditions that influence people’s general and social well-being such as chronic pain, neurological disorders that lead to motor o perceptual impairments, psychological disorders that alter behaviour and social cognition, or physical conditions like eating disorders or present in amputees. It is known that an accurate perception of oneself and of the surrounding environment are both key elements to enjoy mental health and well-being, and that both can be distorted in patients suffering from the clinical conditions mentioned above. In the past few years, multiple studies have shown the effectiveness of VR to modulate such perceptual distortions of oneself and of the surrounding environment through virtual body ownership illusions. This narrative review aims to review clinical studies that have explored the manipulation of embodied virtual bodies in VR for improving mental health, and to discuss the current state of the art and the challenges for future research in the context of clinical care.

Altered Interoceptive Perception and the Effects of Interoceptive Analgesia in Musculoskeletal, Primary, and Neuropathic Chronic Pain Conditions

Chronic pain (CP) severely disrupts the daily life of millions. Interoception (i.e., sensing the physiological condition of the body) plays a pivotal role in the aetiology and maintenance of CP. As pain is inherently an interoceptive signal, interoceptive frameworks provide important, but underutilized, approaches to this condition. Here we first investigated three facets of interoceptive perception in CP, compared with pain-free controls. We then introduce a novel interoceptive treatment and demonstrate its capacity to reduce pain severity in CP, potentially providing complementary analgesic treatments. Study 1 measured interoceptive accuracy, confidence and sensibility in patients (N = 60) with primary, secondary musculoskeletal, and neuropathic CP. Compared with matched controls, CP participants exhibited significantly lower interoceptive accuracy and interoceptive confidence. Pain severity was predicted positively by interoceptive accuracy, anxiety and depression, and negatively by interoceptive confidence. Study 2 tested a promising new interoceptive treatment for CP, in a single-blind between-subjects design (N = 51) with primary, secondary musculoskeletal, and neuropathic CP patients. The treatment specifically activates the C-Tactile system, by means of controlled stimulation of interoceptive unmyelinated afferents, at 3 cm/s with a force of 2.5 mN. This treatment led to significant pain reduction (mean 23%) in the CP treatment group after only 11 min, while CP controls who received comparable but non-interoceptive stimulation reported no change in pain intensity. These studies highlight the importance of interoceptive approaches to CP and demonstrate the potential of this novel method of C-Tactile stimulation to provide complementary analgesic treatments.

Virtual Reality for Anxiety Disorders: Rethinking a Field in Expansion

The principal aim to this chapter is to present the latest ideas in virtual reality (VR), some of which have already been applied to the field of anxiety disorders, and others are still pending to be materialized. More than 20 years ago, VR emerged as an exposure tool in order to provide patients and therapists with more appealing ways of delivering a technique that was undoubtedly effective but also rejected and thus underused. Throughout these years, many improvements were achieved. The first section of the chapter describes those improvements, both considering the research progresses and the applications in the real world. In a second part, our main interest is to expand the discussion of the new applications of VR beyond its already known role as an exposure tool. In particular, VR is enabling the materialization of numerous ideas that were previously confined to a merely philosophical discussion in the field of cognitive sciences. That is, VR has the enormous potential of providing feasible ways to explore nonclassical ways of cognition, such as embodied and situated information processing. Despite the fact that many of these developments are not fully developed, and not specifically designed for anxiety disorders, we want to introduce these new ideas in a context in which VR is experiencing an enormous transformation.

Interactions between cardiac activity and conscious somatosensory perception

Fluctuations in the heart's activity can modulate the access of external stimuli to consciousness. The link between perceptual awareness and cardiac signals has been investigated mainly in the visual and auditory domain. Here, we investigated whether the phase of the cardiac cycle and the prestimulus heart rate influence conscious somatosensory perception. We also tested how conscious detection of somatosensory stimuli affects the heart rate. Electrocardiograms (ECG) of 33 healthy volunteers were recorded while applying near-threshold electrical pulses at a fixed intensity to the left index finger. Conscious detection was not uniformly distributed across the cardiac cycle but significantly higher in diastole than in systole. We found no evidence that the heart rate before a stimulus influenced its detection, but hits (correctly detected somatosensory stimuli) led to a more pronounced cardiac deceleration than misses. Our findings demonstrate interactions between cardiac activity and conscious somatosensory perception, which highlights the importance of internal bodily states for sensory processing beyond the auditory and visual domain.

Major Depressive Disorder Is Associated with Impaired Interoceptive Accuracy: A Systematic Review

Interoception is the sense of the physiological condition of the entire body. Impaired interoception has been associated with aberrant activity of the insula in major depressive disorder (MDD) during heartbeat perception tasks. Despite clinical relevance, studies investigating interoceptive impairments in MDD have never been reviewed systematically according to the guidelines of the PRISMA protocol, and therefore we collated studies that assessed accuracy in detecting heartbeat sensations (interoceptive accuracy, IAc) in MDD (databases: PubMed/Medline, PsycINFO, and PsycARTICLES). Out of 389 records, six studies met the inclusion criteria. The main findings suggest that (i) moderately depressed samples exhibit the largest interoceptive deficits as compared with healthy adults. (ii) difficulties in decision making and low affect intensity are correlated with low IAc, and (iii) IAc seems to normalize in severely depressed subjects. These associations may be confounded by sex, anxiety or panic disorder, and intake of selective serotonin reuptake inhibitors. Our findings have implications for the development of interoceptive treatments that might relieve MDD-related symptoms or prevent relapse in recurrent depression by targeting the interoceptive nervous system.

Demographic-related variables impact subjective experiences of patient wait times and perceived attention afforded in surgical outpatient clinic encounters

INTRODUCTION

Patient satisfaction remains a key component in successful delivery of high-quality healthcare. In this study, we attempted to better understand how patient demographics might influence perception of clinic wait times and determine factors that may positively influence perception of a clinic experience.

METHODS

A prospective study was conducted assessing patient satisfaction during outpatient surgical clinics in minimally invasive, breast, plastic/reconstructive, and orthopaedic surgery between May and September 2017. Patient demographics, subjective and objective assessments of wait time and physician encounter, and qualitative assessments of physician and patient interaction were collected.

RESULTS

150 patients were enrolled with median age between 45 and 54 years old. Patients perceived mean wait times of 22.5 min and contact with physician as 12.3 min. Objective measures of wait and physician-contact times were 30.8 min and 10.7 min. These trends persisted despite surgical specialty and new versus returning patient class. Widowed patients perceived receiving less attention by doctors (p<.05), retirees believed they spent less time with their physician (p<.05), and associate's degree holders as highest education status had greater differences in perceived-versus-actual contact time with their doctor (p<.05). Clinic patients reported high satisfaction scores (>96%) quantifying physician eye-contact (99.3%), attention (99.8%), clarity of clinical communication (98.7%), interest in answering questions (99.2%), and reasonability (98.2%) highly. Patients described their physicians as excellent (99.4%) and were likely to refer their provider to others (99.9%).

CONCLUSION

Our findings suggest qualitative factors of patient encounters including eye contact, attention, communication, interest, and subjective perceptions of time bear more weight in the final assessment of patient satisfaction with care than quantitative factors such as actual wait time and duration of time with provider. This is irrespective of differences in perceived wait and contact times between different groups.

Interoceptive Axes Dissociation in Anorexia Nervosa: A Single Case Study With Follow Up Post-recovery Assessment

Anorexia nervosa (AN) is a disorder characterized by alterations in body perception. Recent literature suggested that AN can also impair the processing of stimuli from inside the body (i.e., interoceptive) however, very few studies performed a complete interoceptive assessment exploring the evolution of the interoceptive dimensions before and after the subject’s recovery. To address this gap in knowledge, this study presented the case of Diana, a 25 years old woman affected by AN. At hospital admission, Diana performed a complete interoceptive assessment for accuracy (IAc), metacognitive awareness (IAw), sensibility (IAs), and interoceptive buffer saturation (IBs) – a new index that behaviourally evaluated the amount of interoceptive processing. Measures were repeated at the end of an outpatients rehabilitative hospital program, after Diana’s recovery. Results were confronted with a control (N = 4) of healthy female subjects. Analyses indicated severe deficits in accuracy, buffer saturation, and sensibility compared to control group. Conversely, metacognitive awareness was pathologically enhanced. After the rehabilitative hospital program, Diana’s clinical condition was largely improved and this reflected back on the interoceptive patterns that appeared restored, with no difference in interoceptive accuracy and metacognition compared to the control group. In conclusion, results indicated a very specific dissociation between interoceptive axes in AN with pervasive deficits in perception and processing that were accompanied by a pathologically enhanced confidence in the wrong perceptions. This case study reported an interesting and unique clinical pattern with a severe dissociation between interoceptive perceptions that nonetheless appeared restored after the subject’s recovery, highlighting the role of interoceptive assessment in the clinical evolution of AN.

Perceptual Content, Not Physiological Signals, Determines Perceived Duration When Viewing Dynamic, Natural Scenes

The neural basis of time perception remains unknown. A prominent account is the pacemaker-accumulator model, wherein regular ticks of some physiological or neural pacemaker are read out as time. Putative candidates for the pacemaker have been suggested in physiological processes (heartbeat), or dopaminergic mid-brain neurons, whose activity has been associated with spontaneous blinking. However, such proposals have difficulty accounting for observations that time perception varies systematically with perceptual content. We examined physiological influences on human duration estimates for naturalistic videos between 1–64 seconds using cardiac and eye recordings. Duration estimates were biased by the amount of change in scene content. Contrary to previous claims, heart rate, and blinking were not related to duration estimates. Our results support a recent proposal that tracking change in perceptual classification networks provides a basis for human time perception, and suggest that previous assertions of the importance of physiological factors should be tempered.

The Past, Present, and Future of Virtual and Augmented Reality Research: A Network and Cluster Analysis of the Literature

The recent appearance of low cost virtual reality (VR) technologies - like the Oculus Rift, the HTC Vive and the Sony PlayStation VR - and Mixed Reality Interfaces (MRITF) - like the Hololens - is attracting the attention of users and researchers suggesting it may be the next largest stepping stone in technological innovation. However, the history of VR technology is longer than it may seem: the concept of VR was formulated in the 1960s and the first commercial VR tools appeared in the late 1980s. For this reason, during the last 20 years, 100s of researchers explored the processes, effects, and applications of this technology producing 1000s of scientific papers. What is the outcome of this significant research work? This paper wants to provide an answer to this question by exploring, using advanced scientometric techniques, the existing research corpus in the field. We collected all the existent articles about VR in the Web of Science Core Collection scientific database, and the resultant dataset contained 21,667 records for VR and 9,944 for augmented reality (AR). The bibliographic record contained various fields, such as author, title, abstract, country, and all the references (needed for the citation analysis). The network and cluster analysis of the literature showed a composite panorama characterized by changes and evolutions over the time. Indeed, whether until 5 years ago, the main publication media on VR concerned both conference proceeding and journals, more recently journals constitute the main medium of communication. Similarly, if at first computer science was the leading research field, nowadays clinical areas have increased, as well as the number of countries involved in VR research. The present work discusses the evolution and changes over the time of the use of VR in the main areas of application with an emphasis on the future expected VR's capacities, increases and challenges. We conclude considering the disruptive contribution that VR/AR/MRITF will be able to get in scientific fields, as well in human communication and interaction, as already happened with the advent of mobile phones by increasing the use and the development of scientific applications (e.g., in clinical areas) and by modifying the social communication and interaction among people.

Does the insula contribute to emotion-related distortion of time? A neuropsychological approach

The literature points to a large distributed brain network involved in the estimation of time. Among these regions, the role of the insular cortex is still poorly understood. At the confluence of emotional, interoceptive, and environmental signals, this brain structure has been proposed to underlie awareness of the passage of time and emotion related time dilation. Yet, this assumption has not been tested so far. This study aimed at exploring how a lesion of the insula affects subjective duration, either in an emotional context or in a non-emotional context. Twenty-one patients with a stroke affecting the insula, either left or right, were studied for their perception of sub and supra second durations. A verbal estimation task and a temporal bisection task were used with either pure tones or neutral and emotional sounds lasting between 300 and 1500 ms and presented monaurally. Results revealed that patients with a right insular lesion, showed less temporal sensitivity than both control participants and patients with a left insular lesion. Unexpectedly, emotional effects were similar in patients and control participants. Altogether, these results suggest a specific role of the right insula in the discrimination of durations, but not in emotion related temporal distortion. In addition, an ear × emotion interaction in control participants suggests that temporal processing of positive and negative sounds may be lateralized in the brain.

Neuroscience of Virtual Reality: From Virtual Exposure to Embodied Medicine

Is virtual reality (VR) already a reality in behavioral health? To answer this question, a meta-review was conducted to assess the meta-analyses and systematic and narrative reviews published in this field in the last twenty-two months. Twenty-five different articles demonstrated the clinical potential of this technology in both the diagnosis and the treatment of mental health disorders: VR compares favorably to existing treatments in anxiety disorders, eating and weight disorders, and pain management, with long-term effects that generalize to the real world. But why is VR so effective? Here, the following answer is suggested: VR shares with the brain the same basic mechanism: embodied simulations. According to neuroscience, to regulate and control the body in the world effectively, the brain creates an embodied simulation of the body in the world used to represent and predict actions, concepts, and emotions. VR works in a similar way: the VR experience tries to predict the sensory consequences of an individual's movements, providing to him/her the same scene he/she will see in the real world. To achieve this, the VR system, like the brain, maintains a model (simulation) of the body and the space around it. If the presence in the body is the outcome of different embodied simulations, concepts are embodied simulations, and VR is an embodied technology, this suggests a new clinical approach discussed in this article: the possibility of altering the experience of the body and facilitating cognitive modeling/change by designing targeted virtual environments able to simulate both the external and the internal world/body.

Toward an Embodied Medicine: A Portable Device with Programmable Interoceptive Stimulation for Heart Rate Variability Enhancement

In this paper, we describe and test a new portable device that is able to deliver tactile interoceptive stimulation. The device works by delivering precise interoceptive parasympathetic stimuli to C-tactile afferents connected to the lamina I spinothalamocortical system. In humans, interoceptive stimulation can be used to enhance heart rate variability (HRV). To test the effectiveness of the device in enhancing HRV, 13 subjects were randomly assigned in a single-blind between-subjects design either to the experimental condition or to the control condition. In the experimental condition, subjects received stimulation with the developed device; in the control condition subjects received stimulation with static non-interoceptive pressure. Subjects’ electrocardiograms (ECG) were recorded, with sampling at 1000 Hz for 5 min as a baseline, and then during the stimulations (11 min). Time domain analyses were performed to estimate the short-term vagally mediated component (rMSSD) of HRV. Results indicated that the experimental group showed enhanced rMSSD, compared to the control group. Moreover, frequency domain analyses indicated that high frequency band power, which reflects parasympathetic activity in humans, also appeared to be enhanced in the experimental group compared to control subjects. Conclusions and future challenges for an embodied perspective of rehabilitative medicine are discussed.

The Perception of Time Is Underestimated in Adolescents With Anorexia Nervosa

Research has revealed reduced temporal discounting (i.e., increased capacity to delay reward) and altered interoceptive awareness in anorexia nervosa (AN). In line with the research linking temporal underestimation with a reduced tendency to devalue a reward and reduced interoceptive awareness, we tested the hypothesis that time duration might be underestimated in AN. Our findings revealed that patients with AN displayed lower timing accuracy in the form of timing underestimation compared with controls. These results were not predicted by clinical, demographic factors, attention, and working memory performance of the participants. The evidence of a temporal underestimation bias in AN might be clinically relevant to explain their abnormal motivation in pursuing a long-term restrictive diet, in line with the evidence that increasing the subjective temporal proximity of remote future goals can boost motivation and the actual behavior to reach them.