Event:

Early life experiences including chronic stress (ELS) are associated with vulnerability to neuropsychiatric disorders, which often commence during adolescence. We studied adolescent rats reared under routine or impoverished, ELS provoking early-life environments, and found cognitive vulnerabilities that became overt later in life, as well as significant reductions in peer-play and sucrose preference. These are measures of anhedonia (inability to experience pleasure), that typically herald major depression. As maternal care is a key source of sensory signals to the developing brain and governs ELS, we used mathematical approaches to analyze dam nurturing behaviors. Unexpectedly, whereas the quantity and typical qualities of maternal care behaviors were indistinguishable in the two environments, their patterns and rhythms differed and influenced emotional and cognitive outcomes. Specifically, unpredictable, fragmented maternal care patterns in impoverished cages translated into high entropy, chaotic sensory signals to the developing offspring brain. These aberrant patterns may disrupt normal maturation of cognitive and emotional brain networks, promoting adolescent anhedonia and cognitive vulnerabilities.