Childhood Trauma Leading To Over-Dominant Brain Stem

A simplified way of describing the structure of the brain is to think of it as comprising three main regions (e.g. MacLean, 1990) that develop in the following order from birth to a person’s early or mid-twenties.

FIRST TO DEVELOP: The brain stem and midbrain :

Main functions : Sensory / motor and basic survival mechanisms (‘fight / flight’)

SECOND TO DEVELOP: The limbic brain :

Main functions: Emotional development, behaviour and attachment

THIRD TO DEVELOP: The cortical brain :

Main function: inhibition, thinking, language, planning, decision-making, abstract thought and learning.



As described above, it is the brain stem’s function to preserve our safety in dangerous situations (by physiologically preparing us for ‘fight or flight’).

However, when a child has been traumatized over an extended period and has been excessively exposed to frightening situations, the brain stem can become overactive and over-dominant so that the brain is on a constant state of ‘red-alert’ (giving rise to feelings of hypervigilance, edginess, agitation and constant fear) even in situations which are, in objective terms, very safe.

IN SHORT, THE CHILD BECOMES ‘LOCKED INTO SURVIVAL MODE’, primed to lash out (figuratively or literally) or run away (again, figuratively or literally). And, of course, in the case of the former, this can lead to him/her being wrongly labelled as ‘bad’ whereas, in fact, his or her behaviour is essentially due to what can reasonably be described as brain injury incurred due to the traumatic events to which s/he has been subjected over a protracted period.



Such children are, in effect, ‘stuck’ at the first stage of brain development shown above (i.e. the brain stem/midbrain developmental stage).

Unfortunately, this means the child is not only locked into feeling constantly hyperalert to anticipated danger and profoundly unsafe but can suffer from other significant impairments (see below):



Being locked into the brain stem development stage also prevents the higher regions of the brain (i.e. the limbic brain and the cortical brain, as described above) from developing correctly, and, therefore, also from functioning correctly.

This can mean that the child is unable to form attachments or control his/her emotions (due to the damage done to the ‘limbic brain’ ) and is also unable properly to perform the functions of the ‘cortical brain’, including inhibition (leading to impulsive behaviour), planning, decision-making, reflecting and learning. Such problems can manifest themselves in numerous ways, including being unable to form friendships at school, ‘misbehaving’ in class and learning difficulties).



‘Bottom-Up’ (as opposed to ‘Top-Down’) therapies such as SENSORIMOTOR PSYCHOTHERAPY can be of benefit to individuals affected by ‘brain stem’ associated problems, and it is generally agreed that these problems should be addressed prior to addressing issues related to the ‘limbic brain’ and ‘cortical brain.’

There is also a growing body of evidence to suggest that the traumatised brain may also be helped to recover using a treatment known as neurofeedback.


MacLean, Paul D. (1990). The triune brain in evolution: role in paleocerebral functions. New York: Plenum Press. ISBN 0-306-43168-8. OCLC 20295730.


David Hosier BSc Hons; MSc; PGDE(FAHE). is reader-supported. When you buy through links on this site, I may earn an affiliate commission.

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