The goal of this set of projects is to use functional magnetic resonance imaging (fMRI) to compare the degree to which brain regions of adolescents and adults are engaged by tasks involving processing of emotionally salient stimuli. Based on developmental continuities in the relevant psychological processes, we anticipate considerable similarity across age groups in the topography of brain regions engaged by relevant tasks. However, we hypothesize that developmental differences in cortico-limbic circuits of adolescents and adults will be reflected in patterns of fMRI activation. Specifically, we hypothesize in both adults and adolescents that attention, threat perception, and memory tasks involving the processing of emotionally salient stimuli will engage the amygdala, cingulate gyrus, and association cortex of medial/inferior prefrontal cortex and temporal regions. Nevertheless, height of task-associated activation is hypothesized to differ between adolescents and adults within these regions. Moreover, prior studies distinguish puberty vs. age-related aspects of cognitive development: some aspects of attention, threat perception, or memory development relate to changes in chronological age whereas other aspects, particularly those involving emotional processes, relate to pubertal status. Therefore, we expect eventually to use emotion-evoking fMRI tasks to test hypotheses on the presence of complementary, distinguishable puberty vs. age-related components of brain development. Due to the limited fMRI database on neurodevelopmental aspects of emotional processes, one initial goal of the current project is to compare brain activation patterns in adults and adolescents, irrespective of pubertal status. A second initial goal is to generate behavioral data in adults and adolescents designed to inform the implementation of future fMRI tasks. Studies accomplishing both goals will facilitate eventual studies designed to distinguish puberty vs. age-related aspects of brain development. To meet these initial goals, the current project implemented a series of studies during the first two years in which data have been collected. For our fMRI studies, brain activation profiles were examined to four sets of emotionally evocative stimuli. This included evocative faces, standardized emotion-inducing picture sets, monetary feedback during a decision task, and threat of a mildly aversive air-puff. In total, an initial set of five fMRI studies were completed in samples of between 14 and 17 psychiatrically healthy adults. Two additional fMRI studies were completed in samples of between 14 and 17 psychiatrically healthy adolescents. In each of these, hypothesized brain activation patterns emerged. For one of these tasks, involving face emotion processing, we compared patterns of activation in adolescents and adults. As hypothesized, this comparison revealed signs of amygdala, orbitofrontal, and medial frontal hyperactivation in adolescents during passive viewing, as well as signs of hyperactivation in these regions in adults during attention manipulations. These results are summarized in three recent publications from our group [1-3]. In an effort to replicate these associations, we have acquired further data sets in other samples that are larger than the initial data sets. We will be analyzing these data during the coming year, with the plan of also publishing these findings. Finally, for our behavioral studies, neuropsychological data were gathered to facilitate the development of new fMRI tasks. These included data on four additional tasks. In these tasks, between 20-60 subjects were studied, including approximately equal numbers of adolescents and adults. One paper concerning these data was recently published [4]. Three additional manuscripts using these data have been submitted and are under-review. We are also in the process of analyzing other data and preparing research reports for other tasks.
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