A primary, and often most troubling, concern of many parents of children with autism spectrum disorders (ASD) is the lack of emotional connectedness or reciprocity with their child. Such concerns predict early treatment-seeking (Twyman et al., 2009). Though a significant source of distress, the mechanisms underlying this deficit are only recently starting to be characterized. One model of the etiology of this deficit is drawn from the social motivation hypothesis (Dawson et al., 1998a;Grelotti et al., 2002;Dawson et al., 2004;Dawson et al., 2005;Schultz, 2005;Monk 2008;Kohls et al., 2009) and holds that this deficit arises from a lack of sensitivity to social rewards. Understanding reward responsiveness is extremely important not only for behavioral (Jerome &Sturmey, 2008;Trosclair-Lasserre et al., 2008) interventions but pharmacologic (Walker, 2008), as there are potential mechanisms for manipulating reward responsiveness, providing a potentially powerful target for intervention. However it is unknown whether there is a general deficit in reward responsiveness, whether more salient rewards are required to trigger a reward response in ASD, or whether the reward response deficit is limited to social stimuli, which would suggest that apparent reward deficits are secondary, rather than primary, and potentially less amenable to direct intervention. This study proposes to test these alternatives by manipulating reward content (social vs. non social) and reward salience (special interest vs. typical rewards) using functional MRI in children with ASD. We will use pictures of the participants'primary caregiver (PC) as salient social rewards and pictures of strangers as typical social rewards. We will use pictures representing the participant's favorite object/activity as salient non-social rewards and pictures representing other participants'favorite objects/activities as typical non-social rewards. Participants will perform an implicit learning task based on Knowlton's well studied probabilistic classification task (Knowlton et al., 1994) where arbitrary stimulus response pairs are implicitly learned over time with rewarded and non-rewarded conditions. Our hypothesis is that children with ASD can indeed respond to and learn from social rewards;however, the social rewards need to be of higher salience than for TD children.
This work stems from the social motivation theory which holds that from a young age, children with ASD, unlike typically developing children, fail to feel a sense of reward or pleasure when seeing their mothers smiling face for example. This failure to experience reward to social stimuli has tremendous negative sequelae which are difficult if not impossible to reverse. Our work will help to better characterize the reward responsiveness of children with ASD and of TD children with the hope of leading to improved pharmacological and behavioral treatment strategies.
