Childhood Experience and the Expression of Genetic Potential: What Childhood Neglect Tells Us About Nature and Nurture

Abstract

Studies of childhood abuse and neglect haveimportant lessons for considerations of natureand nurture. While each child has uniquegenetic potentials, both human and animalstudies point to important needs that everychild has, and severe long-term consequencesfor brain function if those needs are not met. The effects of the childhood environment,favorable or unfavorable, interact with all theprocesses of neurodevelopment (neurogenesis,migration, differentiation, apoptosis,arborization, synaptogenesis, synapticsculpting, and myelination). The time coursesof all these neural processes are reviewed herealong with statements of core principles forboth genetic and environmental influences onall of these processes. Evidence is presentedthat development of synaptic pathways tends tobe a ``use it or lose it'' proposition.Abuse studies from the author's laboratory,studies of children in orphanages who lackedemotional contact, and a large number of animaldeprivation and enrichment studies point to theneed for children and young nonhuman mammals tohave both stable emotional attachments with andtouch from primary adult caregivers, andspontaneous interactions with peers. If theseconnections are lacking, brain development bothof caring behavior and cognitive capacities isdamaged in a lasting fashion.These effects of experience on the brainimply that effects of modern technology can bepositive but need to be monitored. Whiletechnology has raised opportunities forchildren to become economically secure andliterate, more recent inadvertent impacts oftechnology have spawned declines in extendedfamilies, family meals, and spontaneous peerinteractions. The latter changes have deprivedmany children of experiences that promotepositive growth of the cognitive and caringpotentials of their developing brains.