Neural tracking of visual periodic motion.

Periodicity is a fundamental property of biological systems, including human movement systems. Periodic movements support displacements of the body in the environment as well as interactions and communication between individuals. Here, we use electroencephalography (EEG) to investigate the neural tracking of visual periodic motion, and more specifically, the relevance of spatiotemporal information contained at and between their turning points. We compared EEG responses to visual sinusoidal oscillations versus nonlinear Rayleigh oscillations, which are both typical of human movements. These oscillations contain the same spatiotemporal information at their turning points but differ between turning points, with Rayleigh oscillations having an earlier peak velocity, shown to increase an individual's capacity to produce accurately synchronized movements. EEG analyses highlighted the relevance of spatiotemporal information between the turning points by showing that the brain precisely tracks subtle differences in velocity profiles, as indicated by earlier EEG responses for Rayleigh oscillations. The results suggest that the brain is particularly responsive to velocity peaks in visual periodic motion, supporting their role in conveying behaviorally relevant timing information at a neurophysiological level. The results also suggest key functions of neural oscillations in the Alpha and Beta frequency bands, particularly in the right hemisphere. Together, these findings provide insights into the neural mechanisms underpinning the processing of visual periodic motion and the critical role of velocity peaks in enabling proficient visuomotor synchronization.

Influence of facial feedback during a cooperative human-robot task in schizophrenia.

Rapid progress in the area of humanoid robots offers tremendous possibilities for investigating and improving social competences in people with social deficits, but remains yet unexplored in schizophrenia. In this study, we examined the influence of social feedbacks elicited by a humanoid robot on motor coordination during a human-robot interaction. Twenty-two schizophrenia patients and twenty-two matched healthy controls underwent a collaborative motor synchrony task with the iCub humanoid robot. Results revealed that positive social feedback had a facilitatory effect on motor coordination in the control participants compared to non-social positive feedback. This facilitatory effect was not present in schizophrenia patients, whose social-motor coordination was similarly impaired in social and non-social feedback conditions. Furthermore, patients' cognitive flexibility impairment and antipsychotic dosing were negatively correlated with patients' ability to synchronize hand movements with iCub. Overall, our findings reveal that patients have marked difficulties to exploit facial social cues elicited by a humanoid robot to modulate their motor coordination during human-robot interaction, partly accounted for by cognitive deficits and medication. This study opens new perspectives for comprehension of social deficits in this mental disorder.

Moving attractive virtual agent improves interpersonal coordination stability.

Interpersonal motor coordination is influenced not only by biomechanical factors such as coordination pattern, oscillating frequency, and individual differences, but also by psychosocial factor such as likability and social competences. Based on the social stereotype of "what is beautiful is good", the present study aimed at investigating whether people coordinate differently with physically attractive people compared to less attractive people. 34 participants were engaged in an interpersonal coordination task with different looking (virtual) agents while performing at the same time a reaction time task. Results showed that participants had more stable motor coordination with the moving attractive than with the less attractive agent, and that the difference in motor coordination could not be interpreted by a specific attention allocation strategy. Our findings provide the evidence that physical attractiveness genuinely affects how people interact with another person, and that the temporal-spatial coordinated movement varies with the partner's psychosocial characteristics. The study broadens the perspective of exploring the effect of additional psychosocial factors on social motor coordination.

Social priming enhances interpersonal synchronization and feeling of connectedness towards schizophrenia patients.

What leads healthy individuals to abnormal feelings of contact with schizophrenia patients remains obscure. Despite recent findings that human bonding is an interactive process influenced by coordination dynamics, the spatiotemporal organization of the bodily movements of schizophrenia patients when interacting with other people is poorly understood. Interpersonal motor coordination between dyads of patients (n = 45) or healthy controls (n = 45), and synchronization partners (n = 90), was assessed with a hand-held pendulum task following implicit exposure to pro-social, non-social, or anti-social primes. We evaluated the socio-motor competence and the feeling of connectedness between participants and their synchronization partners with a measure of motor coordination stability. Immediately after the coordination task, all participants were also asked to rate the likeableness of their interacting partner. Our results showed greater stability during interpersonal synchrony in schizophrenia patients who received pro-social priming, inducing in their synchronization partner greater feelings of connectedness towards patients. This greater feeling of connectedness was positively correlated with stronger motor synchronization between participants suggesting that motor coordination partly underlies patients' social interactions and feelings of contact with others. Pro-social priming can have a pervasive effect on abnormal social interactions in schizophrenia patients.

Social priming increases nonverbal expressive behaviors in schizophrenia.

Semantic priming tasks are classically used to influence and implicitly promote target behaviors. Recently, several studies have demonstrated that prosocial semantic priming modulated feelings of social affiliation. The main aim of this study was to determine whether inducing feelings of social affiliation using priming tasks could modulate nonverbal social behaviors in schizophrenia. We used the Scrambled Sentence Task to prime schizophrenia patients according to three priming group conditions: pro-social, non-social or anti-social. Forty-five schizophrenia patients, diagnosed according to DSM-IV-TR, were randomly assigned to one of the three priming groups of 15 participants. We evaluated nonverbal social behaviors using the Motor-Affective subscale of the Motor-Affective-Social-Scale. Results showed that schizophrenia patients with pro-social priming had significantly more nonverbal behaviors than schizophrenia patients with anti-social and non-social priming conditions. Schizophrenia patient behaviors are affected by social priming. Our results have several clinical implications for the rehabilitation of social skills impairments frequently encountered among individuals with schizophrenia.

Social motor coordination in unaffected relatives of schizophrenia patients: a potential intermediate phenotype.

Intermediate endophenotypes emerge as an important concept in the study of schizophrenia. Although research on phenotypes mainly investigated cognitive, metabolic or neurophysiological markers so far, some authors also examined the motor behavior anomalies as a potential trait-marker of the disease. However, no research has investigated social motor coordination despite the possible importance of its anomalies in schizophrenia. The aim of this study was thus to determine whether coordination modifications previously demonstrated in schizophrenia are trait-markers that might be associated with the risk for this pathology. Interpersonal motor coordination in 27 unaffected first-degree relatives of schizophrenia patients and 27 healthy controls was assessed using a hand-held pendulum task to examine the presence of interpersonal coordination impairments in individuals at risk for the disorder. Measures of neurologic soft signs, clinical variables and neurocognitive functions were collected to assess the cognitive and clinical correlates of social coordination impairments in at-risk relatives. After controlling for potential confounding variables, unaffected relatives of schizophrenia patients had impaired intentional interpersonal coordination compared to healthy controls while unintentional interpersonal coordination was preserved. More specifically, in intentional coordination, the unaffected relatives of schizophrenia patients exhibited coordination patterns that had greater variability and in which relatives did not lead the coordination. These results show that unaffected relatives of schizophrenia patients, like the patients themselves, also present deficits in intentional interpersonal coordination. For the first time, these results suggest that intentional interpersonal coordination impairments might be a potential motor intermediate endophenotype of schizophrenia opening new perspectives for early diagnosis.

Nonverbal expressive behaviour in schizophrenia and social phobia.

Expressive behaviour plays a crucial role in the success of social interactions. Abnormality of expressive behaviour has been reported in interpersonal interactions of patients suffering from schizophrenia and social phobia, two debilitating mental disorders with important social deficits. However, no study has compared the expressive behaviour in these two disorders. Thirty schizophrenia patients, 21 social phobia patients and 30 healthy controls were evaluated and compared on expressive, cognitive and clinical dimensions. Expressive behaviour was assessed using the Motor Affective subscale of the Motor-Affective-Social-Scale (MASS). Covariables include the Positive and Negative Syndrome Scale (PANSS), the anxiety level Liebowitz-Social-Anxiety-Scale (LSAS) and cognitive tasks. After controlling for depression, schizophrenia and social phobia patients both exhibited significantly fewer expressive behaviours compared to healthy controls. Moreover, our results showed specific signatures: schizophrenia patients performed fewer spontaneous gestures (hand gestures and smiles) whereas social phobia patients had an impaired ability to produce voluntary smiles in comparison to healthy controls. Interestingly, poor social functioning was significantly correlated with a decrease of expressive behaviour for schizophrenia patients. Expressive behaviour is impaired in different ways in social phobia and schizophrenia and is associated in schizophrenia with poorer social functioning. The Motor Affective subscale of the MASS is an interesting tool for assessing the dysfunction of interpersonal expressive behaviour in mental disorders.