Cooperative behavior guided by peer coordination is impaired in a Fragile-X rat model of autism
Cooperative behavior, the ability of individuals to coordinate their actions toward shared goals, is fundamental to survival and social success across species. However, the behavioral mechanisms that support cooperation, and how their disruption leads to social deficits in neurodevelopmental disorders such as autism spectrum disorder (ASD), remain poorly understood. To address these questions, we developed a cooperation task in paired spatial mazes in dyads of wild-type (WT) and Fmr1 knockout (Fmr1) rats, a model of Fragile X syndrome, under deterministic (100%) and probabilistic (50%) reward contingencies. Both WT and Fmr1 rat pairs exhibited mixed leader-follower strategies to coordinate their actions for cooperation, however WT pairs achieved significantly greater cooperation success than Fmr1 pairs. WT and Fmr1 pairs both displayed a follower-tracking-leader strategy during transitions between reward wells, which required partner-directed visual attention, followed by a reactive action to match leader position, with Fmr1 pairs reliant on this strategy to a greater degree. In WT rats, more efficient cooperation was based on a flexible predictive strategy leading to coordination of optimal choice patterns between rat pairs and sensitivity to recent partner choices, whereas Fmr1 rats were significantly weaker in these strategies leading to deficits in adaptive behavior. These findings identify key behavioral strategies for cooperation, reveal their disruption in a rat model of ASD, and provide a framework for linking social cue usage to flexible and strategic cooperative decision-making with relevance to neurodevelopmental disorders.