The maternal brain under stress: Consequences for adaptive peripartum plasticity and its potential functional implications

• There is a large degree of plasticity in the maternal brain during pregnancy and lactation.
• Stress can significantly affect plasticity in the maternal brain.
• Steroid and peptide hormones may mediate changes in maternal brain plasticity under basal and stressed conditions.
• We discuss the implications of these changes in plasticity.

The peripartum period represents a time during which all mammalian species undergo substantial physiological and behavioural changes, which prepare the female for the demands of motherhood. In addition to behavioural and physiological alterations, numerous brain regions, such as the medial prefrontal cortex, olfactory bulb, medial amygdala and hippocampus are subject to substantial peripartum-associated neuronal, dendritic and synaptic plasticity. These changes, which are temporally- and spatially-distinct, are strongly influenced by gonadal and adrenal hormones, such as estrogen and cortisol/corticosterone, which undergo dramatic fluctuations across this period. In this review, we describe our current knowledge regarding these plasticity changes and describe how stress affects such normal adaptations. Finally, we discuss the mechanisms potentially underlying these neuronal, dendritic and synaptic changes and their functional relevance for the mother and her offspring.