Neuroplasticity and Trauma: How the Brain Changes

An Overview of the Brain

“Neurons that fire together, wire together” is a popular summary of an idea from the psychologist Donald Hebb (Hebb, 1949).

The brain grows and changes throughout life. Each time you practise something or learn a new skill, the brain strengthens some connections. When your environment changes, genes can turn on or off, and the brain can adapt to what it senses gives it the best chance of survival. The more you do something, the stronger the connections in the brain become, and the more efficient the process. One classic example is a study of London taxi drivers, carried out before satellite navigation. The drivers had learned to find their way around the whole city and had spent years doing it. Compared with men who did not drive taxis, they had larger posterior hippocampi, a part of the brain involved in spatial memory (Maguire and colleagues, 2000).

With trauma, certain parts of the brain can become much more active, specifically the parts responsible for sensing and reacting to threats. The brain becomes “too good” at this and starts perceiving threat where there is none. Over time, as this pattern strengthens and you become used to living in a state of nervous system arousal, it can feel impossible to find the way back to the safety you once felt. But just as the brain changed to reach this state, it can change again with the right care and attention.

Like Riding a Bike

They say it comes back like riding a bike. The old circuits are still somewhere in the brain. It just needs some time to access them again. So it may be with trauma and the return to the social engagement system described in polyvagal theory. The video The Backwards Brain Bicycle, from Smarter Every Day, shows neuroplasticity at work as a man learns to ride a bicycle whose steering has been reversed.

Triggers and Brain Rewiring

PTSD can bring changes in the brain. One such change is wiring for triggers. A trigger can cause the traumatic event to be relived. Some cases are obvious, such as a war veteran who panics when watching fireworks on New Year’s Eve. For some people, especially those with C-PTSD, triggers can be more difficult to identify.

Triggers are not always consciously known. Sometimes the body remembers things the mind does not. For example, someone may have experienced repeated physical abuse from a caregiver that often happened at mealtimes, at the same table. Even if that detail is forgotten over the years, the body may constantly feel on edge when eating around other people. There may be dozens of these triggers in some cases, and the longer someone lives with PTSD, the more triggers they may accumulate, as the body keeps sensing danger and associating it with whatever is around.

The logical conclusion is to try to become aware of every time you feel triggered, so that you can work out what these hidden triggers are. Unfortunately, it can be trickier than that. It is possible to be triggered without consciously realising it. In one study, people who feared snakes or spiders reacted physically to pictures of them flashed too briefly to be recognised (Öhman and Soares, 1994).

These triggers are rarely static. Say, for example, someone has trauma from being bitten by a dog as a child. They may not fear all dogs. They may have a very kind old dog at home that has never acted aggressively. But when they see other dogs fighting, or have another bad experience with a dog, their brain may begin to shut out the whole category of “dog” as a loving animal. They may begin to fear all dogs and take precautions to avoid them. This fear and avoidance can keep symptoms going, but from their experiences their brain has decided that it is safer to fear all dogs.

What Are the Principles of Neuroplasticity?

Jeffrey Kleim and Theresa Jones described ten principles of how experience changes the brain, drawn mainly from research on rehabilitation after brain injury (Kleim and Jones, 2008). Three may be relevant to therapy. Repetition matters, so new responses take practice. Salience matters, so change comes more easily through what is meaningful to you. Specificity matters too, so practising one skill mainly changes that skill. How far these principles carry over to recovery from trauma has been studied less.

Can You Rewire Your Brain after Trauma?

“Rewiring” is a loose metaphor. The brain keeps changing with experience throughout life. Therapy aims to offer repeated new experiences, such as noticing a trigger and staying steady, which may make other responses easier over time. Change tends to be gradual.