Moderation by depression and anxiety of connectivity among brain areas associated with motivation

Pathological anxiety and depression are prevalent forms of psychopathology and are associated with significant impairment in multiple areas of life, including occupational and social functioning. Although both forms of psychopathology have been heavily researched, the factors involved in their etiology and maintenance are still a matter of debate and require further investigation. Levels of trait approach and avoidance motivation may be relevant for understanding the differential correlates of anxiety and depression, given research indicating that they have distinct relationships with dimensions of trait motivation. An integrative model of the brain regions instantiating the approach and avoidance motivational systems is needed to understand how dysfunction in these systems manifests in anxiety and depression. The present dissertation aims to advance these literatures by proposing a hierarchical model of the neural components implementing the approach and avoidance motivational systems and examining the functional relationships among the proposed brain regions for motivational control. This model is then used to delineate areas of motivational dysfunction associated with pathological anxiety and depression

Exciting fear in adolescence: Does pubertal development alter threat processing?

Adolescent development encompasses an ostensible paradox in threat processing. Risk taking increases dramatically after the onset of puberty, contributing to a 200% increase in mortality. Yet, pubertal maturation is associated with increased reactivity in threat-avoidance systems. In the first part of this paper we propose a heuristic model of adolescent affective development that may help to reconcile aspects of this paradox, which focuses on hypothesized pubertal increases in the capacity to experience (some) fear-evoking experiences as an exciting thrill. In the second part of this paper, we test key features of this model by examining brain activation to threat cues in a longitudinal study that disentangled pubertal and age effects. Pubertal increases in testosterone predicted increased activation to threat cues, not only in regions associated with threat avoidance (i.e., amygdala), but also regions associated with reward pursuit (i.e., nucleus accumbens). These findings are consistent with our hypothesis that puberty is associated with a maturational shift toward more complex processing of threat cues—which may contribute to adolescent tendencies to explore and enjoy some types of risky experiences