fMRI of Unconscious Affect Processing in Adolescence

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DESCRIPTION (provided by applicant): Despite the importance of the perception and processing of emotions to everyday human interaction, there is remarkably little understanding of the neurobiological substrates that influence these processes. Even less is known about how emotion pathways develop from childhood into adulthood. Recent studies of adults suggest that there are lateralized differences in the activation of the amygdala during conscious versus unconscious perception of facial emotion. The investigators' preliminary data suggest that the functioning of the amygdala and prefrontal cortex change dramatically over the adolescent years, but no study has yet examined unconscious facial affect processing in children or adolescents. The proposed research is a preliminary investigation that will use functional magnetic resonance imaging (fMRI) to examine the neurobiological pathways involved in the unconscious perception of emotion during adolescent development. While undergoing Blood Oxygen Level Dependent (BOLD) fMRI, 48 healthy adolescents ranging in age from 11 to 18 years will be presented with photographs of faces that vary by several features that are hypothesized to affect the responses of specific limbic and cortical pathways. In a backward masking paradigm, subjects will view extremely brief presentations (30 ms) of target faces expressing fear, anger, and happiness, which will be immediately replaced by a neutral masking face (970 ms). The backward masking paradigm will prevent subjects from consciously perceiving the affective expressions, although a detectable change in the MR signal that correlates with the target presentation is expected. Target faces will be presented across three visual field conditions (full, left-half only, right-half only) to permit greater precision of the initial lateralized presentation of affect to a single cerebral hemisphere. Data will be analyzed using whole-brain and region based analyses. Based on preliminary data, the investigators hypothesize that activation of the amygdala in response to unconscious affective stimuli will demonstrate age-related changes in lateralization that are both valence and gender specific. Furthermore, they hypothesize that limbic activity is moderated directly by the progressive development of prefrontal cortex during adolescence. The findings from the proposed preliminary research will clarify the role of the prefrontal cortex in modulating affective processing within the limbic system for males and females during development. The proposed research will provide the basis for further work aimed toward mapping the developmental trajectories of affective learning. This knowledge will directly impact the understanding of the neurobiological bases of normal and abnormal emotional processing, and potentially lead to a better understanding of factors leading to emotional dysfunction.