BackgroundUnderstanding social interactions requires the ability to accurately interpret conspecifics' actions, sometimes only on the basis of subtle body language analysis. Here we address an important issue that has not yet received much attention in social neuroscience, that of an interaction between two agents. We attempted to isolate brain responses to two individuals interacting compared to two individuals acting independently.Methodology/Principal FindingsWe used minimalistic point-light displays to depict the characters, as they provide the most straightforward way to isolate mechanisms used to extract information from motion per se without any interference with other visual information. Functional magnetic resonance imaging (fMRI) method was used to determine which brain regions were recruited during the observation of two interacting agents, mimicking everyday social scenes. While the mirror and mentalizing networks are rarely concurrently active, we found that both of them might be needed to catch the social intentions carried by whole-body motion.Conclusions/SignificanceThese findings shed light on how motor cognition contributes to social cognition when social information is embedded in whole-body motion only. Finally, the approach described here provides a valuable and original tool for investigating the brain networks responsible for social understanding, in particular in psychiatric disorders.

Two studies investigated whether typically developing children (TD) and children with autism spectrum disorders (ASD) were able to decide whether two characters were communicating or not on the basis of point-light displays. Point-lights portrayed actors engaged or not in a social interaction. In study 1, TD children (4-10 years old; n = 36) grasped social intentions from body language, with a notable improvement around 7/8. In study 2, children with ASD (6-12 years old; n = 12) could categorize the point-light displays at above-chance levels, but performed less efficiently, especially for the social interaction displays, than TD children (matched to chronological and non-verbal mental age, 6-12 years old; n = 24). An action representation deficit is discussed in relation to a social representation deficit and it is suggested that these deficits might be linked to altered maturational process of the mirror system in ASD.

AIM Postural control is a fundamental component of action in which deficits have been shown to contribute to motor difficulties in children with developmental coordination disorder (DCD). The purpose of this study was to examine anticipatory postural adjustments (APAs) in children with DCD in a bimanual load-lifting task.METHOD Sixteen children with reported motor problems (two females, 14 males; mean age 9y; SD 2y) and 16 typically developing, age-matched children (six females, 10 males; mean age 9y; SD 2y) took part in the study. The task required the children to maintain a stable elbow angle, despite imposed or voluntary unloading of the forearm. APAs were assessed using electromyography and kinematics analysis.RESULTS Although children with DCD could compensate for the consequences of unloading, the results demonstrated that APAs were less efficient in children with DCD than in typically developing children. A positive and significant coefficient of regression between the flexor inhibition latency and the postural stabilization was only found in typically developing children. INTERPRETATIONThe impaired fine-tuning of the muscle contribution and the poor stabilization performances demonstrate poor predictive modelling in DCD.Developmental coordination disorder (DCD) is the term used to describe marked clumsiness without any sign of neurological injury, pervasive developmental disorder, or learning disability.* Performances on daily activities that require motor coordination are substantially poorer than expected. DCD may manifest itself in considerable delays in achieving motor milestones, poor performance in sports, or poor handwriting. 1 The clinical picture of the motor impairment is very heterogeneous, with some children presenting with poor gross motor coordination whilst demonstrating proficiency in fine coordination, and vice versa.Postural deficits have been found in children with DCD. 2 It has been demonstrated that static postural control in children with DCD relies on a greater amount and a more variable patterns of muscular activity than it does in typically developing children of a similar age. 3 Studies exploring balance during quiet standing have yielded inconclusive results. Although Geuze et al. 4 failed to find any clear differences between children with and without DCD, other authors have observed a greater centre of pressure sway in children with DCD than in their typically developing peers. 5 It seems that the former are especially prone to difficulties when placed in novel situations. 4 In more dynamic postural tasks the differences between children with and without DCD in the fine control of postural adjustments become more obvious. By predicting the possible postural disturbance created by movement performance, anticipatory postural adjustments (APAs) allow the body or one of its segments to maintain stability. 6 In a forward-and backward-leaning task, Przysucha et al. 7 observed less efficient postural adaptations in young males with DCD than in males without DCD. Using electromyograp...