The remarkable growth and development of the neural cortex during the earliest years of life can occur only when a child feels emotionally secure in warm, stable relationships. When young children are stressed, fearful, or insecure, the limbic (emotional) area of the brain actually prevents learning from occurring.

Whenever a child feels stressed or frightened, a structure in the limbic system responds by secreting cortisol into the bloodstream. This circulates through the body and washes over the neural cortex, where it prevents neural connections from being formed and strengthened. Even if excellent opportunities for stimulation and learning are present in the environment, children who are stressed cannot take advantage of them to develop their brains. Unable to use the higher, thinking part of the brain, children revert to functioning in the lower area of the brain stem and use the survival mechanisms of fight or flight to cope with their situation. It is only when the period of stress ends, and children again feel secure, that learning and higher-level thought processes can resume.

The relationship among fear, cortisol, and learning exists throughout life. Even adults with mature coping skills cannot learn or even think clearly when under too much stress. Infants, because they are dependent on others to fulfill their every need, are much more likely than individuals of any other age to frequently feel panic or fear.

If children live under stressful conditions for significant periods of time in their first two years, the results are disastrous. For it is during this time that the emotional center of the brain is being refined, and its entire developmental course is altered when it experiences frequent high levels of stress and the corresponding high levels of cortisol. Repeated exposure to a great deal of cortisol programs the child's brain to expect, like, and even seek situations that will lead to the release of cortisol. This happens in much the same way that children who live in a home where food is highly salted learn to prefer it that way. Children who become accustomed to high cortisol begin to live in the brain stem, rather than the thinking cortex, and view each interaction as one that threatens their survival. The teacher who is reaching out to them is not doing so to give a welcoming pat but an aggressive hit or shove. The child, without thinking, immediately responds by hitting the teacher first or running away. It is quite possible that the tremendous increase in seemingly random acts of violence in our society is related to the increased number of children responding to high levels of early stress and fear by living in their brain stems.

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