Introduction ¹

The human brain and all the functions that this amazing organ mediate develop as a reflection of developmental experiences. The young human brain's primary mandate is to perceive, process, and act on information from the environment in order to maximize survival potential.

The first three years of a child’s life are critically important to brain development. Billions of brain cells are formed in the first months of fetal life. After birth, trillions of brain cell connections are established and form the brain’s physical "maps" that govern such things as vision, language, and hearing. Brain cells, or neurons, analyze, coordinate, and transmit information. The brain learns and remembers throughout life by constantly changing its networks of trillions of connections between neurons as a result of stimuli from its environment.

The Growth of Synapses

These connections between neurons are called synapses, which grow stronger with learning and weaken or disappear when not in use. Jumping from one neuron to another, neurotransmitters cross these synapses and cause a response in the brain.

In a new brain, synapses form at a rate of three billion a second. By eight months of life, there are one thousand trillion connections. These gradually begin to decline after this time and by age ten or so, half the connections die off leaving about five hundred trillion that last most of life.

Brain Development

Information flows easily into the brain through "windows" that open for varying duration. These windows of development occur in phases from birth to age twelve when the brain is very actively learning from the environment. It is during this period, and especially the first three years, that the foundations for thinking, language, vision, attitudes, aptitudes, and other characteristics are laid down. As these windows close much of the fundamental architecture of the brain is completed.

Neuron connections that mediate behavior develop rapidly and irreversibly until eight months. Synapses, the connections between neurons, are overproduced during this early postnatal period.

These synapses are then selectively eliminated or amplified in large part as a result of experiences. Selective amplification of specific neuronal groups is believed to occur as a function of the frequency and intensity of environmental stimulation of specific groups of neurons. Once particular patterns of neuronal groups are selected in a mapped area of the brain, encounters with similar stimuli are likely to preferentially activate previously selected neuronal groups. Global mappings, therefore, are centrally involved in the creation of future expectancies of reward and punishment learning. Therefore, interactions between parents, other caregivers, and infants play an intricate role in brain development.

Serotonin and Noradrenaline

Scientists have found a biochemical link in which defective genes and the environment interact to produce abnormal levels of two mind-altering brain neurotransmitters, serotonin and noradrenaline.

Serotonin is the brain’s master impulse modulator for all our emotions and drives. It especially keeps aggression in line. When serotonin levels fall, depression, impulsive aggression, alcoholism, sexual deviance and explosive rage rises. High levels of serotonin cause shyness, obsessive compulsion, fearfulness, lack of self-confidence and unduly dampened aggression.

Noradrenaline is the alarm hormone. It organizes the brain to respond to anger, producing adrenaline and other chemicals that prepare the body to fight or flee. Low levels of noradrenaline cause underarousal, increased tendencies towards premeditated or cold blooded acts of violence and thrill seeking. High levels of noradrenaline cause over- arousal, increased tendencies towards impulsive, hot blooded acts of violence and a rapid heartbeat.

Normally, these two hormones work in smooth transitions with each other: the brain and body are prepared for action when need be and then put back on an even keel when danger is over. But when these chemicals are overactive as a result of persistent stresses encountered during fetal development or early childhood, they can take over genetic regulation. Traumatic experiences set up faulty brain chemistry and manifest as the release of low serotonin and high noradrenaline.

Impact of the Environment on Genes and Brain Functioning

Parents pass on a whole variety of characteristics to their children through their genes but the environment also plays a major role in shaping a child’s individuality by shaping the expression of those genes. Because parents’ characteristic manner of responding to their infants emotional behavior plays such a central role in shaping the infant’s emotional responses to it’s environment, parents may well influence the establishment of individual patterns of brain mapping and ultimately life long behavioral development.

External influences from conception onward, offer the brain experiences. Intellectual, emotional, social, and physical experiences are laid down on the trillions of connections between brain cells that make learning and memory possible. The experiences in the early years interact with genetic makeup to determine how children will think and whether they may become mentally retarded, sick, aggressive, or violent.

Some children, regardless of their social or economic status, have brains that are genetically more vulnerable to stress. They are born that way. In many cases however this genetic predisposition was brought about during pregnancy when the mother experienced high levels of stress, was smoking, or abusing alcohol or drugs.

Studies suggest that threatening environments in early infancy can also trigger imbalances of brain chemicals that influence how genes are expressed. Early experience interacts with genes to lay down a biochemical foundation for a lifetime of intellectual, emotional, and social functioning.

Stresses caused by experiences, such as abuse, poverty, neglect, or sensory deprivation, can actually affect genes. They can switch them on or off at the wrong times, forcing them to build abnormal networks of brain cell connections. Stressful environments have caused genes important for survival to become overexpressed, sometimes making individuals more aggressive, violent, or depressed.

Impact of Stress & Trauma on Brain Development

Stress is necessary to development. Children need to experience challenges through which they can organize appropriate emotional and intellectual responses and come to feel mastery. The infant who is allowed to experience manageable frustration, and control, his or own optimal degree of tension and anxiety (stress) and have available a parent or caregiver for comfort, is one who is developing a flexible, maximally-adaptive physiological apparatus for responding to future stressors. It is excessive stress or severe stress that damages early brain development.

The brain will ultimately organize itself in direct response to the pattern, intensity, and nature of sensory and perceptual experience. During key, critical periods of development, the brain is extremely sensitive to quantity, quality, and pattern of activation of its network of neurons. When stressful events of sufficient duration, intensity, or frequency occur, brain development is altered. In general, the earlier and the more pervasive the stress, the more neurodevelopment will be disrupted.

The brain areas involved in the acute stress response mediate motor behavior, affect regulation, anxiety, arousal, sleep, the startle response, cardiovascular and respiratory function and so forth. Sensitization of these systems by repetitive re-experiencing of a traumatic event leads to dysregulation in these various functions. It is not surprising then, that a traumatized child may, over time, exhibit motor hyperactivity, sleep problems, tachycardia and hypertension, among other dysfuncitons. In other words, the traumatized child is walking around in a persisting fear state.

Damage of severe stress or trauma

The child who is reared in an unpredictable, abusive or neglectful environment will have a brain that has developed to view the world as chaotic, violent, frightening, or devoid of nurturance. This child will be much more susceptible to psychosocial stressors through the course of his or her lifetime and will usually develop a hypervigilant, hyper-active arousal system. If primary relationships are characterized by violence, neglect, and unreliability, intimacy becomes maladaptive.

The number, nature, and pattern of traumatic events all make a difference in whether or not the trauma will be carried forward in a malignant way. The more frequently someone is traumatized, the more likely they are to have symptoms. The brain comes to have alterations in basic physiological functioning. If, for example, a young child is frequently assaulted, it becomes adaptive to over-interpret non-verbal cues as signs of aggression, to quickly act on impulses, and to strike out before being struck. The parts of the brain involved with the stress response will be reactivated when this child is exposed to a reminder of the traumatic event. Furthermore, these parts of the brain can be reactivated when the child simply thinks or dreams about the event. Children (and adults) who have been traumatized often have affective or emotional memories buried deep in their brainstem and midbrain. Over time, the same emotional and behavioral response can be elicited from a much smaller provocative stimulus. After sensitization, a full blown fear response may be evoked by a minor stressor. This, of course, is very often observed in traumatized children.

Early Stress & Trauma Intervention

Each year in the United States over 2 million children are traumatized by physical or sexual abuse or by exposure to domestic or community violence. The key to minimizing the potential damage of any traumatic experience is early intervention. Helping very young children to function more effectively in their social environment may be a very appropriate long-range strategy for preventing mental illness in general and violence in particular. Early interventions should focus on providing stability, predictability, and information. The child born with predisposition for high noradrenaline and fearful responses will remain calm in stressful situations if they are with a parent or caregiver they trust. If the child does not feel secure with his caretaker, noradrenaline and hyperactivity go up.

The major way to affect the primitive parts of the brain of a stressed child is to provide:

• predictability,
• nurturance,
• support, and
• cognitive or insight-oriented interventions which make a child feel safe, comfortable and loved.

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