Probing Social Motivation Heterogeneity in Young Children

Background: There are vast knowledge gaps in understanding neurobiological mechanisms that contribute to the broad heterogeneity seen in social-affective behavior across human populations. This is particularly true for children with neurodevelopmental disorders whereby neural circuitry involving complex mental functions, such as social-affective processing, is disrupted. This processing, which can influence attention, motivation/reward, and emotional regulation, is a difficult construct to test in young children. While it is well documented that children with autism spectrum disorder (ASD) show disruptions in social behaviors, the underlying mechanisms driving those disruptions is less understood. Theories range in explanations that these social deficits arise from a lack of motivation for social interaction, to aversion to social interaction. These knowledge gaps in both understanding and measuring social-affective processes currently limits the design of effective and scalable interventions for improving disrupted social behavior. Strategies and tools are needed to better probe complex internal responses, such as feelings, drives, and motivations independent from language, and to decipher subtle behavioral consequences of these internal responses for low-verbal children including those with neurodevelopmental disorders.

Objectives: There were two goals of this study. The first was to build upon our previously established paradigm of conditioned place preference (CPP) for use in young typically developing (TD) children by adapting the task for use with a social unconditioned stimulus. The second goal was to use the social CPP task to probe whether the social interaction phenotype in children with ASD is due to an aversion to social interactions, or alternatively, a lack of reward from social interactions.

Methods: Typically developing children and children with ASD aged 36-60 months participated in this social CPP task. The task utilized Pavlovian conditioning methods in which a conditioned stimulus (CS) was repeatedly paired with an unconditioned stimulus (US), which elicited an unconditioned response (UR), and after successful conditioning, the CS elicited a conditioned response (CR) similar to the UR. Using a novel social experimenter as the US, and a custom-designed child-friendly arena, a castle, as the CS, the CS was paired with the US across four conditioning trials and we then measured place preference scores when the US was not present.

Results: Our results demonstrate that TD children display a robust social CPP (p<0.05) and that CPP scores correlate with sub-scales of the Mullen Scales of Early Learning. In comparison, the ASD group shows more heterogeneous conditioning scores in the social CPP task, revealing less preference for the social US in our preliminary data.

Conclusions: There is significant heterogeneity in the behavioral characteristics and genetic underpinnings of social behaviors in both TD children and children with ASD. The establishment of reliable and robust behavioral paradigms that can reveal differences in motivation, reward, and aversion for social stimuli, as utilized in this study, promises to transform approaches to assessment and intervention in young or low-verbal children, and to illuminate potential underlying neurobiological mechanisms responsible for the observed heterogeneity. This will allow for more precise interventions to target and reduce core social-affective symptoms of ASD.