The influence of unpredictable, fragmented parental signals on the developing brain.

Mental illnesses originate early in life, governed by environmental and genetic factors. Because parents are a dominant source of signals to the developing child, parental signals - beginning with maternal signals in utero - are primary contributors to children's mental health. Existing literature on maternal signals has focused almost exclusively on their quality and valence (e.g. maternal depression, sensitivity). Here we identify a novel dimension of maternal signals: their patterns and especially their predictability/unpredictability, as an important determinant of children's neurodevelopment. We find that unpredictable maternal mood and behavior presage risk for child and adolescent psychopathology. In experimental models, fragmented/unpredictable maternal care patterns directly induce aberrant synaptic connectivity and disturbed maturation of cognitive and emotional brain circuits, with commensurate memory problems and anhedonia-like behaviors. Together, our findings across species demonstrate that patterns of maternal signals influence brain circuit maturation, promoting resilience or vulnerability to mental illness.