Experience, brain, and behavior: the importance of a head start.

Nature and nurture stand in reciprocity, not opposition. All children inherit-along with their parents' genes-their parents, their peers, and the communities they live in. Development unfolds in an ecologic and a social setting which, just like the genes, is decisive in shaping the organism. The social niche is a crucial link between parents and offspring, an envelope of life chances. It is high time to replace the false dichotomy between nature versus nurture by a more inclusive trio: nature, niche, and nurture. Major brain pathways are specified in the genome, but the learned connections between brain and behavior are fashioned by social experience. The luxuriant overgrowth of neurons and their processes in embryonic and early life provides the substrate for environmentally induced structural change. Activity selects out the synapses that will persist; inactivity results in regression and apoptosis. Learning begins in utero and accelerates after birth. Responsive interactions between infants, their parents, and other caretakers is crucial to biological no less than psychosocial development. Comprehensive pediatric care can help provide a head start to enhance brain development and put the mind on the road to adaptive maturity.