If we suffer severe, protracted childhood trauma that involved us living in an environment in which we were constantly anticipating danger from an abusive parent or primary carer it is possible that our ‘survival’ brain was so frequently activated that it became dominant at the expense of the development and functioning of the ‘learning’ brain.

CHILDHOOD TRAUMA AND TOXIC STRESS LEADING TO THE ‘SURVIVAL BRAIN’ BECOMING OVERDOMINANT:

A key part of the survival brain is the amygdala which acts as the brain’s alarm system. If during childhood, this is repeatedly overactivated it can eventually, figuratively speaking,  get ‘stuck’ in the ‘ON’ position causing us to become preoccupied with threat and to live in a state of fear with the perpetual feeling that catastrophe is imminent and that it is, therefore, necessary for us to stay on ‘red alert’, even though we may not be consciously aware of the reasons underlying this highly distressing state (i.e. the toxic stress to which we were subjected in childhood). 

Overdominance of the survival brain due to early life trauma will tend to lead to dysfunctional, maladaptive survival-based coping in adulthood. As well as constantly anticipating danger, the brain stuck in survival mode can lead to extreme, reactive, defensive aggression (driven by the unconscious motive that aggression can constitute a form of defense – the ‘fight response’), avoidance (related to the ‘flight response’), and dissociation.

Although such behaviours develop in response to the original trauma, if the ‘survival brain’ has been overactivated over a long period and become dominant, these behaviours will become generalized to life experiences outside of the original trauma that involves interpersonal vulnerability and uncertainty (e.g. a general inability to trust).

Children who are driven by survival-based coping behaviours as a result of their home environments may avoid school (‘flight’ response), misuse drugs and alcohol (to achieve a state of dissociation), become defiant (fight-response), become socially withdrawn (‘flight’ response), indulge in high-risk behaviours (to achieve a state of ‘dissociation’) in an attempt to reduce feelings of powerlessness, vulnerability, anxiety, depression, mental distress and extremes of hypo- and hyper-arousal (i.e. the very low arousal associated with dissociation or extreme overarousal). In such children, this can lead to extreme overactivation of the brain’s stress and reward pathways which, in turn, can lead to a sudden change from the ‘learning brain’ being ‘in charge’ to the ‘survival brain’ being in charge (Lewis, 2005).

WHY DOES CHILDHOOD TRAUMA IMPAIR THE DEVELOPMENT AND FUNCTIONALITY OF THE ‘LEARNING BRAIN’?

Various areas of the brain associated with learning can have their development impaired by severe, protracted childhood trauma, including damage to the development of the Broca’s area (a part of the brain associated with the production of speech). One of the adverse effects of damage to this area of the brain is that survivors of childhood trauma may find it especially difficult to verbalize their traumatic experiences (Hull, 2002).

Parts of the frontal cortex may also be damaged by prolonged childhood trauma which reduces the brain’s ability to inhibit survival responses (fight/flight/freeze) in response to triggers that are not (objectively speaking) threatening (Ali et al., 2011) e.g. misperceiving neutral facial expressions as threatening facial expressions or a neutral tone of voice as a hostile tone of voice, especially if it is the facial expression or tone of voice by a person in authority, such as a teacher.

Furthermore, trauma can damage the brain’s reward pathways (see above) and this can result in individuals anticipating less pleasure (compared to the average person) from completing tasks and achieving goals. This, in turn, can reduce levels of motivation (Pechtel and Pizzagali, 2011).

Prolonged childhood trauma can increase levels of the stress hormone known as cortisol in our systems and this excess of cortisol can damage a part of the brain known as the hippocampus, even to the extent that the volume of this part of the brain is reduced which impairs its ability to function correctly. Amongst other adverse effects, this can harm declarative memory (also known as ‘explicit’ memory where information is explicitly – i.e. consciously and deliberately – stored and retrieved, attention, and learning (Pechtel and Pizzagali, 2011).

Damage to the prefrontal cortex caused by extensive childhood trauma adversely affects our ability to problem-solve, think logically, self-soothe, reflect on our actions, curb our impulses, and behave in flexible ways. As the thinking and reflective skills of the prefrontal cortex are required to shut down the amygdala’s and brain stem’s (constituting the ‘survival brain’) threat response once it (i.e. the prefrontal cortex) has established there is, after consideration, no danger, damage done to it by trauma can impair its ability to ‘switch off’ the ‘survival brain’ (i.e. the amygdala and brain stem). This means that if we are frightened by something that turns out not to be a threat, after all, it takes us much longer than the average person to bring our brain stem’s and amygdala’s overreaction (and associated symptoms such as rapid heartbeat, hyperventilation, etc.) under control.

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David Hosier BSc Hons; MSc; PGDE(FAHE).