Date of Award

5-6-2009

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

First Advisor

Joan Kaufman

Abstract

Child maltreatment is a significant contributor to psychopathology, including depressive disorders and Post-Traumatic Stress Disorder (PTSD). Multiple studies have demonstrated important changes in emotion processing and regulation in children exposed to early life stress, but the underlying neural mechanism is unknown. There is significant variability in outcome in children exposed to early life stress which may be moderated by genetic polymorphisms in the serotonin transporter. This study was designed as a functional Magnetic Resonance Imaging project using dichotic listening to study emotion-processing pathways and interhemispheric transfer. Eighteen children were recruited in a two-by-two factorial design with maltreatment and serotonin genotype as factors. Main effects of genotype were seen in increased activation in the amygdala and orbitofrontal cortex (OFC) to attended angry stimuli. No main effects of trauma (either as a categorical or continuous variable) were seen, and there was no interaction of trauma and genotype. Non-significant differences were found in the pattern of emotion processing between the maltreatment groups seen in the superior temporal gyrus. The results are consistent with a growing body of literature that has identified genotype as an important factor in neural pathways. The increased amygdala and OFC activity was seen in the controls as well as the traumatized children with the vulnerable genotype. An emerging question is how these differences lead to psychopathology in some instances and not others.

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