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    • Replicating prior studies we found that non anxious

    2018-10-25

    Replicating prior studies, we found that non-anxious individuals are capable of learning from positive outcomes, regardless of age (Moutsiana et al., 2013). However, this ability was impaired in both anxious adolescents and adults. Although anxious adolescents recalled expected Blebbistatin from high-value peers, they were unable to recall unexpected positive feedback, and thus could not draw on the ‘pleasant surprise’ of being proven wrong to update subsequent predictions. While memory impairments were relatively specific among anxious adolescents, there were more general or pervasive among anxious adults, who failed to recall both expected and unexpected positive outcomes from high-value peers. This finding may indicate that memory for social feedback is impaired in anxious adults regardless of its valence. Our focus on positive PEs reflects the fact that neural response during positive PE processing varied as a function of social anxiety and age group; no such effects were observed during negative PE processing, when participants expected positive, but received negative, feedback. Given that models of reinforcement learning emphasize the importance of both positive and negative PEs for learning, the specificity of our findings are somewhat surprising. Despite an emphasis on similarities in the neural mechanisms mediating positive and negative PEs, the two types of events can generate somewhat different neural responses (Redish, 2013). In fact, some evidence suggests positive and negative PEs differentially influence learning in social contexts similar to those in the current study. For instance, recent work demonstrated that healthy youths and adults effectively learned from positive, but not negative, PEs generated by social feedback (Jones et al., 2014). Thus, the present findings could reflect the fact that positive and negative PEs differentially influence social learning, and that the neural circuits engaged by negative social PEs fail to vary as a function of social anxiety and age group. Although null results must be interpreted with caution, these findings suggest that it is the dysregulated response to positive, but not negative, social PEs that may contribute to social anxiety in adolescents. One major limitation in the current study is the relatively small number of trials for some event types in our primary analyses. As the complexity of questions posed in fMRI research grows, task complexity has also increased. Our primary analysis parsed social experiences based on peer value, expectations, and feedback. This precisely mirrored the task structure, but came at a cost: some event types had relatively few trials. Although other well-established paradigms utilize similarly sparsely-populated events (e.g., Lebron-Milad et al., 2012; Milad et al., 2007, 2009, 2013; Visser et al., 2013; Wheelock et al., 2014), the small number of trials raises concerns about the stability of results. Research aimed at extending these findings should consider increasing the sample size, and/or implementing novel paradigms that include more trials for each event type while maintaining task complexity needed to retain external validity (Jarcho et al., 2013). A second limitation was our categorical approach to studying age and social anxiety. This facilitated the interpretation of complex higher-order interactions, which would have been difficult to interpret in the context of continuous, rather than categorical, analyses. A shortcoming of this approach is that we were unable to test whether unique patterns of brain response occurred during specific developmental phases (Blakemore and Mills, 2014; Forbes and Dahl, 2010, 2012; Spielberg et al., 2014a,b; van den Bos et al., 2012). Although we hypothesize that the greatest difference in brain function emerges during adolescence, puberty was not assessed via exam or hormonal assay. Thus, developmental phase could not be characterized with appropriate specificity (Blakemore et al., 2010). Moreover, since adolescents were not stratified by age according to puberty, we were unable to differentiate the effects of age and puberty on brain or behavioral outcomes (Blakemore et al., 2010). A categorical approach also precluded analyses based on severity of social anxiety symptoms. Although a dimensional approach to the study of psychopathology is critical, treatment is most commonly delivered to individuals who meet specific diagnostic criteria. Thus, treating social anxiety as a categorical variable was more closely in line with the overarching goal of our research, which seeks to inform potential treatment strategies.