The Association of Postpartum Mood and Neural Responses to Infant-Related and Generally Rewarding Stimuli: An fMRI Study
Thesis or dissertation
University of Exeter
Abstract Background: The neurobiological basis of human maternal behaviour has primarily been explored functional magnetic resonance imaging (fMRI). Structures including the nucleus accumbens (NAcc) orbitofrontal cortex/ventromedial prefrontal cortex (OFC/VMPFC) and amygdala are consistently and specifically activated in the maternal brain by infant-related stimuli and thought to be important for the experiences of pleasure and reward and the evaluation of emotional salience in response to a range of rewarding stimuli. Less is known about how these brain areas respond in mothers experiencing low mood or Postpartum Depression (PPD). Methods: During fMRI, mothers 3-9 months postpartum with a range of subclinical depressive symptoms completed a task involving the anticipation and receipt of monetary reward and a second task eliciting maternal reward using unknown infant faces. Participants completed general and postpartum-specific questionnaire measures of mood. Correlations were used to explore associations between neural responses to different rewarding stimuli in pre-determined regions of interest (ROIs). Results: When anticipating monetary reward compared to baseline, mothers higher in anhedonia and lower in trait positive affect showed relative deactivation in the right NAcc and amygdala. Exploratory analyses suggested that quicker reaction times (RTs) to distressed baby faces was associated with higher state positive affect and less activation in the right NAcc and bilateral amygdala in response to distressed baby compared to adult faces. Deactivation of the left NAcc was associated with higher postnatal depressive symptoms. Conclusions: Altered neural correlates of monetary reward anticipation may be a more sensitive marker of anhedonic depressive symptoms than reward outcome and thus should be assessed separately. Monetary reward paradigms might be less sensitive to mothering-specific depressive symptoms. Postnatal depressive symptoms may be linked to reward system recruitment but specifically in response to infant relative to adult distress.
Doctorate in Clinical Psychology