Dysfunction of the motivational brain: evidence from anxiety and schizophrenia

Impairments in motivational systems are at the core of distinct maladaptive goal-directed behaviors in psychiatric disorders. In this thesis, we examine the neurocognitive deficits underlying abnormally low approach motivation in schizophrenia with negative symptoms, and abnormally high avoidant motivation in anxiety with overdefensive behaviors. We first systematically integrate previous neuroimaging findings on different stages of reward processing in schizophrenia by conducting a coordinate-based meta-analysis. Next, we examine the dopaminergic brain system in schizophrenia in relation to social amotivation by using resting state functional magnetic resonance imaging. Converging results suggest that hypo-active dopaminergic brain areas and their weakened connections with brain areas related to top-down control may contribute to amotivation and maladaptive approach behaviors in schizophrenia. By manipulating emotional context of risk decision making, and experimentally dissociating subjective aversion to risk from aversion to loss, we examined the neural basis of risk preference in anxiety. Collectively, we show that heightened risk-avoidant behaviors in anxiety are associated with hyperactivation of brain areas involved in emotional processing but lower coupling of brain systems implicated in top-down control. Together with previous findings, we proposed a model of maladaptive motivation in psychiatric disorders, which highlights adequate top-down/bottom-up modulations on valuation of approach-avoidance motivation in adaptive behaviors and the underlying neural pathways of psychiatric disorders, especially for anxiety and schizophrenia. This thesis provides neuroimaging evidence and scientific understanding of the neurocognitive mechanisms underlying maladaptive goal-directed behaviors in anxiety and schizophrenia, which have widespread implications for the improvement of diagnostics and treatment for various psychiatric disorders.