Psychological and physiological evidence for an initial 'Rough Sketch' calculation of personal space

Neural correlates of personal space regulation in psychosis: role of the inferior parietal cortex

Regulation of interpersonal distance or "personal space" (PS; the space near the body into which others cannot intrude without eliciting discomfort) is a largely unconscious channel of non-verbal social communication used by many species including humans. PS abnormalities have been observed in neuropsychiatric illnesses, including schizophrenia. However, the neurophysiological basis of these abnormalities remains unknown. To investigate this question, in this study, functional magnetic resonance imaging (fMRI) data were collected while individuals with psychotic disorders (PD; n = 37) and demographically-matched healthy control (HC) subjects (n = 60) viewed images of faces moving towards or away from them. Responses of a frontoparietal-subcortical network of brain regions were measured to the approaching versus the withdrawing face stimuli, and resting-state fMRI data were also collected. PS size was measured using the classical Stop Distance Procedure. As expected, the PD group demonstrated a significantly larger PS compared to the HC group (P = 0.002). In both groups, a network of parietal and frontal cortical regions showed greater approach-biased responses, whereas subcortical areas (the striatum, amygdala and hippocampus) showed greater withdrawal-biased responses. Moreover, within the PD (but not the HC) group, approach-biased activation of the inferior parietal cortex (IPC) and functional connectivity between the IPC and the ventral/limbic striatum were significantly correlated with PS size. This study provides evidence that PS abnormalities in psychotic illness involve disrupted function and connectivity of the PS network. Such brain-behavior relationships may serve as objective treatment targets for novel interventions for schizophrenia and related psychotic illnesses.

Aberrant personal space is associated with paranoia, altered stress regulation, and unfavourable outcomes at 6 months' follow-up in schizophrenia

Paranoia is a central feature of schizophrenia and linked with poor outcomes. Paranoid experience is sometimes hard to identify in the clinical interview. In contrast, personal space (PS) measures detected patients with paranoia with excellent sensitivity and specificity. Here we test whether we can substantiate aberrant PS regulation in paranoia and whether PS was associated with stress markers and longitudinal outcomes. We included 144 participants (92 patients with schizophrenia spectrum disorders and 52 age and sex-matched healthy controls). We measured PS and stress markers during two behavioural tasks on interpersonal distance. In addition, we assessed social outcomes at baseline and after 6 months. Data corroborated that paranoia increased PS. Moreover, we confirmed that PS detected paranoia with excellent sensitivity (92%) at 1.1 m, and severe paranoia with 87% sensitivity and 81% specificity at 1.6 m. In addition, stress (Electrodermal activity) during the PS task was associated with paranoia and PS. Furthermore, higher stress at baseline predicted less improvement of social outcome after 6 months. Finally, improvement of PS over 6 months was associated with improvement of social functioning. PS may indeed serve as a simple bedside test for paranoia. Furthermore, results have direct implications in clinical practice as they suggest that it is advisable to maintain increased PS with paranoid patients. In addition, altered stress regulation and persistently increased PS may indicate unfavourable outcomes in the short-term follow-up. Thus, patients with persistently increased PS may benefit from special therapeutic attention.

Social distancing between personal belongings during the COVID-19 pandemic

Background

The COVID-19 pandemic has led to instructions and suggestions from governments and experts to maintain social (physical) distance between people to prevent aerosol transmission of the virus, which is now becoming the norm. Thus, we examined whether the pandemic extended the distance between personal belongings.

Methods

We recruited 68 university students and instructed them to place their belongings on a long table following another participant (i.e., confederate). We measured the physical distance between the two belongings (i.e., the participant's and the confederate's). We collected data between June 10, 2022 and January 23, 2023. Pre-pandemic data was from Ariga (2016). Analysis was completed with one-tailed t-tests.

Results

Compared with the pre-pandemic results, via one-tailed t-test, the distance between the two belongings during the pandemic was significantly longer. Our results supported the hypothesis that the psychological framework for processing people's belongings has dramatically changed during this pandemic.

Conclusion

This change may have been driven by social distancing practices or an increase in perceived vulnerability to disease. Our results provide new implications for future public spatial design, in other words, not only the distance between people, but also the distance between their belongings.

Enhancing social functioning using multi-user, immersive virtual reality

Rates of loneliness and other forms of social disconnection have been increasing worldwide. Prior studies have suggested that brief behavioral interventions can teach skills that may improve social functioning and connection but, currently, access to such interventions is limited. One previously untested approach for addressing this gap is to teach these skills using immersive, multi-user virtual reality (VR). To measure the feasibility of this approach, 33 young adults experiencing social discomfort were enrolled in a study of a VR-based application called Reconnecting with Ourselves and Others in virtual Meetings (ROOM), which delivered a previously validated, mindfulness-based intervention. Satisfaction ratings, qualitative feedback, and quantitative measures of aspects of social functioning, including social comfort, interpersonal distance, and facial affect recognition, were collected from participants. All of the participants attended more than half of the sessions and 90.3% found ROOM to be beneficial and useful. In addition, comfort with others in the real world (p = 0.02) and facial affect recognition accuracy (p = 0.02) significantly increased, while interpersonal distances remained unchanged, following ROOM. An immersive, multi-user VR intervention may represent one feasible, scalable approach for disseminating skills that can improve social functioning and connection. Trial registration Clinicaltrial.org # NCT06360562.

Altered representation of peripersonal and interpersonal space in psychopathology

The space surrounding the body, and the regulation of this buffer zone play a central role in adaptive behavior, with direct implications for psychopathology. The physical distance that we choose to maintain between ourselves and others for social comfort is known as Interpersonal Distance (IPD), whereas the action space that marks the perceptual border between the self and the external world is known as Peripersonal Space (PPS ). While both IPD and PPS represent personal space, they are distinct constructs, each associated with different methodologies. Here we review the existing literature on IPD and PPS to elucidate their distinct and common contributions to psychiatric conditions including schizophrenia, autism, anxiety, and others. Altered representation and regulation of IPD and PPS were associated with clinical symptoms and social impairments across a wide range of psychiatric disorders, underscoring the important role of the self-other boundary and personal space regulation in adaptive social behavior. Future research should clarify the relationship between IPD and PPS and specify risk factors for self-other boundary dysregulation and associated psychopathologies.

Mesoscale Brain Mapping: Bridging Scales and Modalities in Neuroimaging - A Symposium Review

Advances in the spatiotemporal resolution and field-of-view of neuroimaging tools are driving mesoscale studies for translational neuroscience. On October 10, 2023, the Center for Mesoscale Mapping (CMM) at the Massachusetts General Hospital (MGH) Athinoula A. Martinos Center for Biomedical Imaging and the Massachusetts Institute of Technology (MIT) Health Sciences Technology based Neuroimaging Training Program (NTP) hosted a symposium exploring the state-of-the-art in this rapidly growing area of research. "Mesoscale Brain Mapping: Bridging Scales and Modalities in Neuroimaging" brought together researchers who use a broad range of imaging techniques to study brain structure and function at the convergence of the microscopic and macroscopic scales. The day-long event centered on areas in which the CMM has established expertise, including the development of emerging technologies and their application to clinical translational needs and basic neuroscience questions. The in-person symposium welcomed more than 150 attendees, including 57 faculty members, 61 postdoctoral fellows, 35 students, and four industry professionals, who represented institutions at the local, regional, and international levels. The symposium also served the training goals of both the CMM and the NTP. The event content, organization, and format were planned collaboratively by the faculty and trainees. Many CMM faculty presented or participated in a panel discussion, thus contributing to the dissemination of both the technologies they have developed under the auspices of the CMM and the findings they have obtained using those technologies. NTP trainees who benefited from the symposium included those who helped to organize the symposium and/or presented posters and gave "flash" oral presentations. In addition to gaining experience from presenting their work, they had opportunities throughout the day to engage in one-on-one discussions with visiting scientists and other faculty, potentially opening the door to future collaborations. The symposium presentations provided a deep exploration of the many technological advances enabling progress in structural and functional mesoscale brain imaging. Finally, students worked closely with the presenting faculty to develop this report summarizing the content of the symposium and putting it in the broader context of the current state of the field to share with the scientific community. We note that the references cited here include conference abstracts corresponding to the symposium poster presentations.

Interdigitated Columnar Representation of Personal Space and Visual Space in Human Parietal Cortex

Personal space (PS) is the space around the body that people prefer to maintain between themselves and unfamiliar others. Intrusion into personal space evokes discomfort and an urge to move away. Physiologic studies in nonhuman primates suggest that defensive responses to intruding stimuli involve the parietal cortex. We hypothesized that the spatial encoding of interpersonal distance is initially transformed from purely sensory to more egocentric mapping within human parietal cortex. This hypothesis was tested using 7 Tesla (7T) fMRI at high spatial resolution (1.1 mm isotropic), in seven subjects (four females, three males). In response to visual stimuli presented at a range of virtual distances, we found two categories of distance encoding in two corresponding radially-extending columns of activity within parietal cortex. One set of columns (P columns) responded selectively to moving and stationary face images presented at virtual distances that were nearer (but not farther) than each subject's behaviorally-defined personal space boundary. In most P columns, BOLD response amplitudes increased monotonically and nonlinearly with increasing virtual face proximity. In the remaining P columns, BOLD responses decreased with increasing proximity. A second set of parietal columns (D columns) responded selectively to disparity-based distance cues (near or far) in random dot stimuli, similar to disparity-selective columns described previously in occipital cortex. Critically, in parietal cortex, P columns were topographically interdigitated (nonoverlapping) with D columns. These results suggest that visual spatial information is transformed from visual to body-centered (or person-centered) dimensions in multiple local sites within human parietal cortex.SIGNIFICANCE STATEMENT Recent COVID-related social distancing practices highlight the need to better understand brain mechanisms which regulate "personal space" (PS), which is defined by the closest interpersonal distance that is comfortable for an individual. Using high spatial resolution brain imaging, we tested whether a map of external space is transformed from purely visual (3D-based) information to a more egocentric map (related to personal space) in human parietal cortex. We confirmed this transformation and further showed that it was mediated by two mutually segregated sets of columns: one which encoded interpersonal distance and another that encoded visual distance. These results suggest that the cortical transformation of sensory-centered to person-centered encoding of space near the body involves short-range communication across interdigitated columns within parietal cortex.

Personal space increases during the COVID-19 pandemic in response to real and virtual humans

Personal space is the distance that people tend to maintain from others during daily life in a largely unconscious manner. For humans, personal space-related behaviors represent one form of non-verbal social communication, similar to facial expressions and eye contact. Given that the changes in social behavior and experiences that occurred during the COVID-19 pandemic, including "social distancing" and widespread social isolation, may have altered personal space preferences, we investigated this possibility in two independent samples. First, we compared the size of personal space measured before the onset of the pandemic to its size during the pandemic in separate groups of subjects. Personal space size was significantly larger in those assessed during (compared to those assessed before) the onset of the pandemic (all d > 0.613, all p < 0.007). In an additional cohort, we measured personal space size, and discomfort in response to intrusions into personal space, longitudinally before and during the pandemic, using both conventional and virtual reality-based techniques. Within these subjects, we found that measurements of personal space size with respect to real versus virtual humans were significantly correlated with one another (r = 0.625-0.958) and similar in magnitude. Moreover, the size of personal space, as well as levels of discomfort during personal space intrusions, increased significantly during (compared to before) the COVID-19 pandemic in response to both real and virtual humans (all d > 0.842, all p < 0.01). Lastly, we found that the practice of social distancing and perceived (but not actual) risk of being infected with COVID-19 were linked to this personal space enlargement during the pandemic (all p < 0.038). Taken together, these findings suggest that personal space boundaries expanded during the COVID-19 pandemic independent of actual infection risk level. As the day-to-day effects of the pandemic subside, personal space preferences may provide one index of recovery from the psychological effects of this crisis.

Neural Correlates of Variation in Personal Space and Social Functioning in Schizophrenia and Healthy Individuals

BACKGROUND

Changes in the regulation of interpersonal distance, or "personal space" (PS), have been repeatedly observed in schizophrenia and, in some studies, linked to negative symptoms. However, the neurobiological basis of these impairments is poorly understood.

METHODS

Personal space measurements, functional connectivity of a brain network sensitive to intrusions into PS, and symptoms of social withdrawal and anhedonia were assessed, and associations among these outcomes measured, in 33 individuals with a psychotic disorder (primarily schizophrenia [SCZ]) and 36 control subjects (CON).

RESULTS

Personal space size was significantly higher (P = .002) and PS permeability (reflecting the capacity to tolerate intrusions into PS) was significantly lower (P = .021) in the SCZ relative to the CON group, and both measures were significantly correlated with social anhedonia and withdrawal in the full sample (all P < .007). Moreover, functional connectivity between the PS and default mode (DM) networks was significantly correlated with the permeability, but not the size, of PS in the full sample and in the SCZ and CON groups separately, and with social withdrawal in the SCZ group. Lastly, the association between PS-DM network connectivity and social withdrawal in the SCZ group was fully mediated by PS permeability.

DISCUSSION

Neural and behavioral aspects of PS regulation are linked to social motivation in both healthy individuals and those with psychotic disorders, suggesting that measurements of PS could serve as transdiagnostic markers of social functioning.