Evidence for ERP biomarkers of eating disorder symptoms in women

A scoping review and index of body stimuli in psychological science

Naturalistic body stimuli are necessary for understanding many aspects of human psychology, yet there are no centralized databases of body stimuli. Furthermore, there are a high number of independently developed stimulus sets lacking in standardization and reproducibility potential, and a general lack of organization, contributing to issues of both replicability and generalizability in body-related research. We conducted a comprehensive scoping review to index and explore existing naturalistic whole-body stimuli. Our research questions were as follows: (1) What sets of naturalistic human whole-body stimuli are present in the literature? And (2) On what factors (e.g., demographics, emotion expression) do these stimuli vary? To be included, stimulus sets had to (1) include human bodies as stimuli; (2) be photographs, videos, or other depictions of real human bodies (not computer generated, drawn, etc.); (3) include the whole body (defined as torso, arms, and legs); and (4) could include edited images, but still had to be recognizable as human bodies. We identified a relatively large number of existing stimulus sets (N = 79) which offered relative variability in terms of main manipulated factors and the degree of visual information included (i.e., inclusion of heads and/or faces). However, stimulus sets were demographically homogenous, skewed towards White, young adult, and female bodies. We identified significant issues in reporting and availability practices, posing a challenge to the generalizability, reliability, and reproducibility of body-related research. Accordingly, we urge researchers to adopt transparent and accessible practices and to take steps to diversify body stimuli.

Cybersecurity in neural interfaces: Survey and future trends

With the joint advancement in areas such as pervasive neural data sensing, neural computing, neuromodulation and artificial intelligence, neural interface has become a promising technology facilitating both the closed-loop neurorehabilitation for neurologically impaired patients and the intelligent man-machine interactions for general application purposes. However, although neural interface has been widely studied, few previous studies focused on the cybersecurity issues in related applications. In this survey, we systematically investigated possible cybersecurity risks in neural interfaces, together with potential solutions to these problems. Importantly, our survey considers interfacing techniques on both central nervous systems (i.e., brain-computer interfaces) and peripheral nervous systems (i.e., general neural interfaces), covering diverse neural modalities such as electroencephalography, electromyography and more. Moreover, our survey is organized on three different levels: (1) the data level, which mainly focuses on the privacy leakage issue via attacking and analyzing neural database of users; (2) the permission level, which mainly focuses on the prospects and risks to directly use real time neural signals as biometrics for continuous and unobtrusive user identity verification; and (3) the model level, which mainly focuses on adversarial attacks and defenses on both the forward neural decoding models (e.g. via machine learning) and the backward feedback implementation models (e.g. via neuromodulation and stimulation). This is the first study to systematically investigate cybersecurity risks and possible solutions in neural interfaces which covers both central and peripheral nervous systems, and considers multiple different levels to provide a complete picture of this issue.

Event-related potentials during mental rotation of body-related stimuli in spinal cord injury population

Mental rotations of body-related stimuli are known to engage the motor system and activate body schema. Sensorimotor deficits following spinal cord injury (SCI) alter the representation of the body with a negative impact on the performance during motor-related tasks, such as mental rotation of body parts. Here we investigated the relationship between event-related potentials in SCI participants and the difficulty in mentally rotating a body-part. Participants with SCI and healthy control subjects performed a laterality judgment task, in which left or right images of hands, feet or animals (as a control stimulus) were presented in two different orientation angles (75° and 150°), and participants reported the laterality of the stimulus. We found that reaction times of participants with SCI were slower for the rotation of body-related stimuli compared to non-body-related stimuli and healthy controls. At the brain level, we found that relative to healthy controls SCI participants show: 1) reduced amplitudes of the posterior P100 and anterior N100 and larger amplitudes of the anterior P200 for overall stimuli; 2) an absence of the modulation of the rotation related negativity by stimulus type and rotation angles. Our results show that body representation changes after SCI affecting both components of early stimulus processing and late components that process high-order cognitive aspects of body-representation and task complexity.

Body image and self-perception in women with navel piercings

The present study investigated how women’s body image and body-perceptual processes are affected by navel piercings, an embellishment of the abdominal region women often feel negatively about. We probed perceptual (response times), cognitive (surveys), affective (aesthetic ratings) and neural (event-related potentials, ERPs) facets of (own) body perception. We found that navel piercings are primarily motivated by the desire to enhance one’s body image, and can significantly improve bodily self-perception relative to before and to imagined removal of the piercing. Hence, body image concerns in women with navel piercings were found to be comparable to those of a control group; and their aesthetic ratings of other women’s abdomens only differed, positively, for images depicting navel piercings. ERPs indicated that the sight of navel piercings enhances early structural encoding of bodies as well as late emotional-motivational processes, especially in women with navel piercings. We further found a strong self-advantage in both cortical and behavioural responses during recognition of own and others’ abdomens, especially for images displaying the piercing. Altogether, findings suggest that navel piercings become strongly, and beneficially, integrated into women’s bodily self image. Such piercings may thus be seen as expressions of body care that can protect against self-harming thoughts and behaviours.

Interfacing neural constructs with the Hierarchical Taxonomy of Psychopathology: 'Why' and 'how'

The Hierarchical Taxonomy of Psychopathology (HiTOP) represents a crucial step forward in the empirical refinement of psychiatric nosology. Although grounded in factor analyses of clinical symptoms and affiliated traits, HiTOP encourages research using measures of other types, including neural-system variables, to clarify coherent processes contributing to the hierarchical structure of psychopathology. However, systematic strategies for interfacing HiTOP dimensions with neural-system variables have not been put forth. We discuss reasons for considering neurobiological systems in relation to HiTOP (i.e. 'why') and propose alternative strategies that might be used to develop an interface between HiTOP and neurobiology (i.e. 'how'). In particular, we highlight potential advantages and limitations of establishing this interface through reference to (i) HiTOP dimensions themselves, or conventional personality trait models linked to HiTOP; (ii) alternative trait constructs designed to link conventional personality models and neurobiological measures; and (iii) mechanistic models of neurobiological processes relevant to HiTOP constructs, derived from computational modelling. We discuss the importance of establishing an interface between HiTOP and neurobiology to develop a more comprehensive, mechanistic understanding of psychopathology and to guide the refinement of the HiTOP model. Such efforts have the potential to guide the development and provision of effective, individualized psychological treatment.

Distinct neural response to visual perspective and body size in the extrastriate body area

Neuroimaging research has independently implicated the extrastriate body area (EBA) in distinguishing between different visual perspectives and morphologies of bodies within visual processing. However, the combined processing of these physical attributes towards neural EBA response remains unclear, and may be crucial in influencing higher-order, aesthetic evaluation of bodies. Indeed, EBA alterations amongst eating disorder patients have been associated with disturbances in body image, and disruption to EBA activity amongst healthy individuals has been shown to influence aesthetic evaluations made towards bodies. Therefore, the present study used images of slim and large female bodies viewed from egocentric and allocentric perspectives, to investigate neural EBA response amongst healthy females (N = 30). In addition, participants provided behavioural aesthetic and weight evaluations of all model stimuli. Results revealed an interaction, bilaterally, between visual perspective and body size towards EBA activity, with multi-voxel pattern analysis revealing distinct neural patterns between the four conditions. However, EBA activity did not relate to non-clinical eating disorder psychopathology. No direct relationship was found between EBA activity and behavioural evaluations of model stimuli; however, a whole brain analysis revealed that higher-order, prefrontal regions were associated with cognitive evaluations of large bodies. Taken together, our results suggest that the EBA is an integral core region in discriminating between multiple physical attributes of the body, which is likely to provide important information to higher-order brain regions which make aesthetic evaluations towards bodies.

Investigating the Components of Body Image Disturbance Within Eating Disorders

Body image disturbance has been highlighted as a common characteristic within the development and maintenance of clinical eating disorders (EDs), represented by alterations in an individual's bodily experience. However, whilst the perceptual stability of the sense of body ownership has been investigated in ED patients, the stability of the sense of body agency in those with ED is yet to be examined. Therefore, body ownership and body agency were investigated using the moving rubber hand illusion, alongside measures of explicit and implicit body satisfaction. Furthermore, with evidence demonstrating a direct link between perceptual and cognitive-affective components of body image in the healthy population, the relationship between measures of body perception and body satisfaction was investigated. Results showed that both ED and healthy individuals displayed a similar subjective experience of illusory ownership and agency towards the fake hand, following voluntary movement. However, whilst both groups initially overestimated their own hand width prior to the illusion, the ED group displayed a significant reduction in hand size estimation following the illusion, which was not matched to the same degree in healthy individuals. In addition, ED individuals displayed a significantly lower body satisfaction compared with healthy females, on both an explicit and implicit level. Such implicit outcomes were shown to be driven specifically by a weaker association between the self and attractiveness. Finally, a significant relationship was observed between specific perceptual measures and implicit body satisfaction, which highlights the important link between perceptual and cognitive-affective components of one's body image. Together, such findings provide a useful foundation for further research to study the conditions in which these two components relate with regard to body image and its disturbance, particularly in relation to the prognosis and treatment of EDs.

Evidence for altered configural body processing in women at risk of disorders characterized by body image disturbance

Two studies were conducted to assess appearance-related visual processing mechanisms in populations at risk of disorders characterized by body image disturbance. Using inverted stimuli, Experiment 1 assessed visual processing mechanisms associated with body, face, and house viewing in adolescents. Experiment 2 applied the same protocol to assess appearance-related configural processing in high- and low-risk adolescent women, and women recovering from disorders characterized by body image disturbance. Experiment 1 found evidence for typical configural face and body processing, although adolescent women reported higher levels of body image concern (BIC) and self-objectified to a greater extent than adolescent men. In Experiment 2, typical body inversion effects were seen in the low-risk group, whilst there was some evidence to suggest a disruption to the configural processing of body stimuli in high-risk adolescents and in women recovering from body image disorders. Women in recovery were also quicker to respond to all stimuli, whilst high-risk adolescents took longer to respond to bodies than to other stimuli. Configural face processing was intact in all groups, and effects did not directly relate to BIC or self-objectification. These findings have implications for future research looking to inform early interventions and treatment, suggesting that there could be a tendency to visually process individual body parts at the expense of the whole-body form in women at risk of developing body image disorders, as well as those in recovery.

Early visual ERPs show stable body-sensitive patterns over a 4-week test period

Event-related potential (ERP) studies feature among the most cited papers in the field of body representation, with recent research highlighting the potential of ERPs as neuropsychiatric biomarkers. Despite this, investigation into how reliable early visual ERPs and body-sensitive effects are over time has been overlooked. This study therefore aimed to assess the stability of early body-sensitive effects and visual P1, N1 and VPP responses. Participants were asked to identify pictures of their own bodies, other bodies and houses during an EEG test session that was completed at the same time, once a week, for four consecutive weeks. Results showed that amplitude and latency of early visual components and their associated body-sensitive effects were stable over the 4-week period. Furthermore, correlational analyses revealed that VPP component amplitude might be more reliable than VPP latency and specific electrode sites might be more robust indicators of body-sensitive cortical activity than others. These findings suggest that visual P1, N1 and VPP responses, alongside body-sensitive N1/VPP effects, are robust indications of neuronal activity. We conclude that these components are eligible to be considered as electrophysiological biomarkers relevant to body representation.

Lateralized occipito-temporal N1 responses to images of salient distorted finger postures

For humans as social beings, other people’s hands are highly visually conspicuous. Exceptionally striking are hands in other than natural configuration which have been found to elicit distinct brain activation. Here we studied response strength and lateralization of this activation using event-related potentials (ERPs), in particular, occipito-temporal N1 responses as correlates of activation in extrastriate body area. Participants viewed computer-generated images of hands, half of them showing distorted fingers, the other half showing natural fingers. As control stimuli of similar geometric complexity, images of chairs were shown, half of them with distorted legs, half with standard legs. The contrast of interest was between distorted and natural/standard stimuli. For hands, stronger N1 responses were observed for distorted (vs natural) stimuli from 170 ms post stimulus. Such stronger N1 responses were found for distorted hands and absent for distorted chairs, therefore likely unrelated to visuospatial processing of the unusual distorted shapes. Rather, N1 modulation over both hemispheres – but robustly right-lateralized – could reflect distorted hands as emotionally laden stimuli. The results are in line with privileged visual processing of hands as highly salient body parts, with distortions engaging neural resources that are especially activated for biological stimuli in social perception.