Table 1.

Findings of functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) studies on the mesolimbic reward system in PPD. Abbreviations: NAc, nucleus accumbens; MAO-A, monoamine oxidase-A.

Year	Authors	Sample	Reward region Method Stimulus	Result in mothers with PPD (relative to healthy mothersunless otherwise noted)
2007	Silverman et al.	PPD women 6–8 weeks postpartum Healthy women 6–8 weeks postpartum	Striatum fMRI Positive words	↓ activation
2011	Moses-Kolko et al.	PPD women <10 weeks postpartum Healthy women <10 weeks postpartum	Striatum fMRI Monetary reward task	= Initial activation but ↑ attenuation to baseline
2012	Moses-Kolko et al.	PPD women early postpartum Healthy women early postpartum Non-postpartum depressed Non-postpartum healthy	Striatum PET	↓ D2/3 receptor binding with postpartum state but no differences between depressed and healthy postpartum women
2012	Laurent and Ablow	Depressed mothers 18 months postpartum Non-depressed mothers 18 months postpartum	NAc, striatum, OFC fMRIOwn infant cry	↓ Activation
2013	Laurent and Ablow	Depressed mothers 18 months postpartum Non-depressed 18 months postpartum	Striatum, OFC fMRI Own infant joy faces	↓ Activation
2015	Sacher et al.	PPD women <18 months postpartum Healthy postpartum women who cry due to sad mood <18 months postpartum Asymptomatic healthy postpartum women <18 months postpartum Healthy non-postpartum women	Striatum PET	↑ Increased MAO-A in PPD women and postpartum women who cry
2016	Moses-Kolko et al.	17–20 year old mothers and non-mothers varying in levels of depressive symptoms 16 weeks postpartum	Striatum fMRI Monetary reward	↑ Activity in non-mothers, but ≠ in mothers, with depressive symptoms
2017	Ho and Swain	Depressed mothers Non-depressed mothers	Functional connectivity fMRI Baby cry task	↓ Functional connectivity between the NAc and the amygdala in depressed mothers, ↑ in healthy mothers
2017	Morgan et al.	18–22 year old mothers varying in levels of depressive symptoms 17 weeks postpartum	Dorsal and ventral striatum fMRI Positive (i.e. happy) adult faces	↓ Activation in mothers with higher depressive symptoms; for mothers with higher depressive symptoms, ↑ response associated with more positive caregiving, opposite pattern for mothers with lower symptoms