The sense of agency (SoA) indicates a person’s ability to feel her/his own motor acts as actually being her/his, and through them to exert control over the course of external events. Disruptions in SoA may profoundly affect the individual’s functioning, as observed in several neuropsychiatric disorders.

This is the first article to systematically review studies that investigated intentional binding (IB), a quantitative proxy for SoA measurement, in neurological and psychiatric patients.

Eligible were studies of IB involving patients with neurological and/or psychiatric disorders. The research adhered to the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

We included 15 studies involving 692 individuals. Risk of bias was low throughout studies. Eligible studies dealt with data from 357 patients with neuropsychiatric disorders matched with 335 HCs. Of included patients, 95 were with schizophrenia (SCZ), 30 with a putative prodromal psychosis (PP), 21 with borderline personality disorder (BPD), 66 with Parkinson’s disease (PD), 38 with an autism spectrum disorder (ASD), 29 with functional movement disorders (FMDs), 25 with Gilles de la Tourette syndrome (GTS), 52 with anorexia nervosa (AN; 22 with active disorder and 30 after they had recovered), and 10 with Cortico-Basal syndrome (CBS).

Temporal binding was calculated in eleven studies using variations of the experimental procedure introduced by Haggard et al. (Haggard et al. Nat Neurosci 2002;5 382-385)(Figure 1, A), while four studies utilized a different paradigm named interval estimation (IE)(Figure 1, B).

Image:

Abnormally increased action-outcome binding was found in schizophrenia and in patients with Parkinson’s disease taking dopaminergic medications or reporting impulsive-compulsive behaviours. A decreased IB effect was observed in Tourette’s disorder and functional movement disorders whereas increased action-outcome binding was found in patients with cortico-basal syndrome. The extent of IB deviation from healthy control values correlated with the severity of symptoms in several disorders. Inconsistent effects were found for autism spectrum disorders, anorexia nervosa, and borderline personality disorder. Findings pave the way for treatments specifically targeting SoA in neuropsychiatric disorders where IB is altered.

None Declared

In schizophrenia, there is evidence for anomalies in the extension and plasticity of the peripersonal space (PPS), the portion of space surrounding our body, plastically shaped through motor experiences. An impaired multisensory integration at the PPS level would underpin the disembodiment, a core feature of the disorder linked to subjective perturbations of the sense of self (“Self-disorders”) and of the intersubjective dimension (“schizophrenic autism”).

The present study was aimed at: 1) exploring possible associations between PPS data, psychopathological dimensions, and subjective experiences in schizophrenia; 2) identifying a specific PPS profile in patients with early-onset schizophrenia.

A motor training with a tool was used to assess the PPS size and boundaries demarcation in twenty-seven schizophrenia outpatients. Moreover, they underwent a thorough psychopathological evaluation with the Positive And Negative Syndrome Scale (PANSS), the Examination of Anomalous Self Experience scale (EASE) and the Autism Rating Scale (ARS). Subsequently, the sample was divided into early (EOS) and adult-onset (AOS) subgroups, that were compared with respect to their PPS and psychopathological profiles.

PPS features (size and boundaries demarcation) were associated with PANSS negative score, subjective experiences of existential reorientation (EASE Domain 5 scores) and traits of schizophrenic autism (ARS scores; Fig. 1). PPS parameters (Fig. 2) and ARS scores, but not PANSS and EASE differentiated between early and adult-onset subgroups.

Image:

Image 2:

Our results suggest a link between PPS patterns, negative symptoms, and disturbances of the subjective experience, particularly in the intersubjective domain, in schizophrenia. Moreover, they candidate specific PPS profiles and schizophrenic autism traits as EOS markers.

None Declared

A primary disruption of the bodily self is considered a core feature of schizophrenia patients (SCZ). The “disembodied” self would be underpinned by an inefficient body-related multisensory integration mechanism occurring in the Peripersonal Space (PPS). PPS is a plastic sector of space surrounding our body, whose extent is altered in SCZ. Although PPS represents a malleable interface marking the perceptual border between self and others, no study has investigated the potential alteration of its plasticity in SCZ.

We investigated the PPS extension and its plasticity in SCZ and their potential correlations with the clinical scales.

Thirty SCZ and thirty healthy controls (HC) underwent a multisensory task to estimate PPS boundary before and after a motor training. Patients were also administered the Positive And Negative Syndrome Scale (PANSS) and the Examination of Anomalous Self-Experience (EASE).

Data confirm a narrower PPS extent in SCZ than in HC, whereas no differences in PPS expansion was found in the two groups after the motor training (Figure 1). Positive symptoms were associated directly with PPS extent and inversely with PPS plasticity. No associations were found between PPS and EASE domains. Figure1: Graphical representation of PPS expansion in SCZ and HC. Both panels show individual normalized sigmoid fits

The present study suggests a narrower PPS extent and a preserved PPS plasticity in SCZ with respect to HC. Both PPS extent and plasticity are related to the severity of positive symptoms. These results highlight the potential role of rehabilitation interventions in order to improve patients’ weakened body boundary.

No significant relationships.

The awareness of one's body constitutes a basic experience of Self which modulates the individual engagement in social interactions. Indeed, Interoception Sensitivity (IS), an index of individual ability to represent one’s own internal body states, is implicated in the autonomic regulation in interpersonal context. Schizophrenia deficits in Self-experience and awareness, which frequently entail anomalies in self-other relationship, capture the ever-growing attention of researchers. Nevertheless, IS and autonomic regulation of schizophrenic patients in social context are completely new and not yet investigated aspects of Schizophrenia.

To investigate whether Schizophrenia could be associated with lower IS and with a dysfunctional autonomic regulation during social interaction.

24 chronic schizophrenia patients, and a matched group of healthy controls, performed a Social and a Non-social task while respiratory sinus arrhythmia (an index of autonomic regulation) was measured. In the Social task participants viewed an experimenter performing a caress-like movement at different distances from their hand. In the Non-social task a metal stick was moved at the same distances from the participants’ hand. As measure of IS, a cardiac Mental Tacking Task was performed.

Comparing to controls, Schizophrenia patients presented lower IS, absence of relation between IS and autonomic regulation, and an anomalous autonomic regulation in social and non-social contexts.

Deficits in Self-experience, associated with Schizophrenia, could be extended to patients’ sensitivity to internal bodily signals. Moreover, the observed altered autonomic regulation will be part of interpersonal interaction deficit frequently associated to Schizophrenia.

Anorexia Nervosa (AN) is characterized by body-size overestimation that reflects a distortion of body-representation. Self-body recognition can be both implicit and explicit. The former is based on cognitive and perceptual mechanisms, the latter relies on motor simulation. Previous studies showed that participants, when submitted to a hand laterality judgment task (Implicit task) that required mental rotation showed better performances when the stimuli consisted of their own rather than other's hand (self-advantage). By contrast, the self-advantage was absent when self-recognition (Explicit task) was explicitly required.

This study aimed to investigate whether the overestimation of anorexic's own body size extended to the motor representation of the bodily-self influencing the implicit self-advantage. Furthermore, we assessed the possible relationship between the implicitly recognition of one's own body part and Interoceptive Sensitivity (IS; sensitivity to stimuli originating inside of the body).

Healthy Controls (HC) and restrictive AN patients were submitted both to Implicit and Explicit tasks with self and other's hands presented in the original size or modified to look fatter or thinner. We also assessed participants’ IS by means of a heartbeat perception task.

As previously reported, HC showed specific self-advantage effect only when a motor simulation is required. Furthermore higher IS is related to faster performances only in the implicit task in which a mental motor rotation. The differences between AN patients and HC concerning IS and bodily-self recognition will be also discussed.