The Amazing Human Brain and Human Development

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Lesson 5: Plasticity, Memory, and Cortical Modulation in the Brain
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Plasticity, Memory, and Cortical Modulation in the Brain

The brain changes in a use-dependent fashion. All parts of the brain can modify their functioning in response to specific patterns of activation -- or to chronic activation. These use-dependent changes in the brain result in equivalent changes in cognition. This is what we recognize as cognitive learning. Similarly, emotional functioning (social learning), motor-vestibular functioning (e.g., the ability to write, type, ride a bike) and state-regulation capacity (e.g., resting heart rate) all exemplify the brain's ability to make use-dependent changes.

Conversely, you cannot change any part of the brain that you are not activating! No one could learn to play golf by sitting in a classroom and listening to Tiger Woods talk about how to shoot a low score. In order to learn -- to change the brain -- the experience has to activate the part of the brain that mediates the function you are trying to learn; the right parts of the cortex must be activated and receptive to learn traditional "cognitive" concepts such as we teach in schools, for example.

A mismatch between modality of teaching and the receptive portions of a specific child's brain can occur. This is particularly true when considering the learning experiences of the traumatized child. Classroom learning cannot occur if the child is in either a persistent state of arousal and anxiety, or of dissociation. When in this state, the key parts of the cortex are not receptive to cognitive information that is not relevant to survival. The traumatized child's brain is essentially unavailable to process efficiently the complex cognitive information being conveyed by the teacher.

Trauma Impairs Interpretation

The traumatized child frequently has significant impairment in social and emotional functioning. Hyper-vigilant children frequently develop remarkable non-verbal skills in proportion to their verbal skills (street smarts). They often over-read (misinterpret) non-verbal cues. Eye contact is read as a threat, or a friendly touch is interpreted as an antecedent to seduction and rape. These assessments might have been accurate in the world they came from.

During early development, these traumatized children spent so much time in a low-level state of fear that they were focused primarily on non-verbal cues. Once out of such an environment, it is still difficult for the child's brain to interpret (relearn) these innocent looks and touches as benign.

 These children are often labeled as learning disabled. These difficulties with cognitive organization contribute to a more primitive, less mature style of problem solving -- with violence often being employed as a "tool."

This principle is critically important in understanding why a traumatized child -- in a persistent state of arousal -- can sit in a classroom and not learn. The brain of this child has different areas activated -- different parts of the brain controlling his functioning. The capacity to internalize new verbal cognitive information depends upon having portions of the frontal and related cortical areas activated, which in turn requires a state of attentive calm. Sadly, this is a state that the traumatized child rarely achieves.

Various developmental stages as they pertain to the brain and behavior. Image courtesy of Bruce D. Perry, M.D., Ph.D.
Various developmental stages as they pertain to the brain and behavior. Image courtesy of Bruce D. Perry, M.D., Ph.D.

The above table illustrates the various developmental stages as they pertain to the brain and behavior. Note that when a child is threatened, he or she is likely to act in an "immature" fashion. Regression, a retreat to a less-mature style of functioning and behavior, is commonly observed in all of us when we are physically ill, sleep-deprived, hungry, fatigued, or threatened. When we regress -- in response to a real or perceived threat -- our behavior is mediated (primarily) by less-complex brain areas.

Baseline State of Arousal

If a child has been raised in an environment of persistent threat, the child will have an altered baseline such that the internal state of calm is rarely obtained. The traumatized child will have a "sensitized" alarm response, over-reading verbal and non-verbal cues as threatening. This increased reactivity will result in dramatic changes in behavior in the face of seemingly minor provocative cues. Often, over-reading of threat will lead to a "fight or flight" reaction and impulsive violence. The child will view his violent actions as defensive.

Children exposed to significant threat will "re-set" their baseline state of arousal such that even when no external threats or demands are present, they will be in a physiological state of persistent alarm. As external stressors are introduced (e.g., a complicated task at school, a disagreement with a peer) the traumatized child will be more "reactive." Even a relatively small stressor can instigate a state of fear or terror. The cognition and behavior of the child will reflect his or her state of arousal.

No part of the brain can change without being activated. You can't instruct someone in the French language while they are asleep, nor can you teach a child to ride a bike by drawing a picture on a blackboard.

The increased baseline level of arousal and increased reactivity in response to a perceived threat plays a major role in the various behavioral and cognitive problems associated with traumatized children.


Life as a Constant Test

Children in a state of fear retrieve information from the world differently than children who feel calm. We all are familiar with test anxiety. Imagine what life would be like if all experiences invoked a similar and persistent feeling of anxiety. If a child has information stored in cortical areas, but is very fearful at a specific moment, the information becomes inaccessible.

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