Impaired vitality form recognition in autism.

Along with the understanding of the goal of an action ("what" is done) and the intention underlying it ("why" it is done), social interactions largely depend on the appraisal of the action from the dynamics of the movement: "how" it is performed (its "vitality form"). Do individuals with autism, especially children, possess this capacity? Here we show that, unlike typically developing individuals, individuals with autism reveal severe deficits in recognizing vitality forms, and their capacity to appraise them does not improve with age. Deficit in vitality form recognition appears, therefore, to be a newly recognized trait marker of autism.

Impairment of actions chains in autism and its possible role in intention understanding.

Experiments in monkeys demonstrated that many parietal and premotor neurons coding a specific motor act (e.g., grasping) show a markedly different activation when this act is part of actions that have different goals (e.g., grasping for eating vs. grasping for placing). Many of these "action-constrained" neurons have mirror properties firing selectively to the observation of the initial motor act of the actions to which they belong motorically. By activating a specific action chain from its very outset, this mechanism allows the observers to have an internal copy of the whole action before its execution, thus enabling them to understand directly the agent's intention. Using electromyographic recordings, we show that a similar chained organization exists in typically developing children, whereas it is impaired in children with autism. We propose that, as a consequence of this functional impairment, high-functioning autistic children may understand the intentions of others cognitively but lack the mechanism for understanding them experientially.