Environmental influences on neural plasticity, the limbic system, emotional development and attachment: a review.

The effects of early environmental influences on neural plasticity, the limbic system, and social and emotional development are reviewed and an illustrative case study is briefly discussed. Deprived or abnormal rearing conditions induce severe disturbance in all aspects of social and emotional functioning, and effect the growth and survival of dendrites, axons, synapses, interneurons, neurons, and glia. The amygdala, cingulate, and septal nuclei develop at different rates which correlate with the emergence of wariness, fear, selective attachments, play behavior, and the oral and phallic stages of development. These immature limbic nuclei are "experience-expectant," and may be differentially injured depending on the age at which they suffer deprivation. The medial amygdala and later the cingulate and septal nuclei are the most vulnerable during the first three years of life. If denied sufficient stimulation these nuclei may atrophy, develop seizure-like activity or maintain or form abnormal synaptic interconnections, resulting in social withdrawal, pathological shyness, explosive and inappropriate emotionality, and an inability to form normal emotional attachments.