TIRCIA · General public
Neuroplasticity: why the brain can change
What science says about the brain’s capacity to reorganise itself at any age, and what this means after trauma
By Marie-Agnès Thulliez · Author · Publishing Director6-minute read
For a long time, the adult brain was thought to be fixed: we were born with a stock of neurons, and all that remained was to lose them. We now know this is wrong: the adult brain keeps changing its connections throughout life, according to what we experience, learn and repeat. Whether new neurons are still born in adults remains a matter of debate (Sorrells et al., 2018; Boldrini et al., 2018). In 2025, however, a study found cells capable of becoming neurons in the adult hippocampus, an area involved in memory, in quantities that varied greatly from one person to another (Dumitru et al., 2025).
This capacity is called neuroplasticity. It explains why difficult experiences leave traces, and also why change is possible.
What is neuroplasticity?
Our brain contains billions of neurons linked to one another by connections. Every time we think, feel or act, certain circuits are activated. The more a circuit is used, the stronger its connections become; the less it is used, the weaker they grow. This idea, proposed in 1949 by the psychologist Donald Hebb, is often summed up in a phrase later popularised by the neurobiologist Carla Shatz: “neurons that fire together wire together”.
Neuroplasticity is the brain’s capacity to change its connections, and sometimes even its structure, in response to experience. It is especially strong in childhood, and it continues into adulthood.
What the studies show
Two studies that have become famous illustrate this phenomenon well:
| Study | What was observed | What it shows |
|---|---|---|
| Maguire et al., 2000 | 16 London taxi drivers, who have to memorise thousands of streets | The back of the hippocampus, an area linked to spatial memory, was larger than in men who were not taxi drivers, and all the more so the longer they had worked in the job (the front, by contrast, was slightly smaller). A later study followed trainees: only those who passed the exam showed this change (Woollett and Maguire, 2011). |
| Draganski et al., 2004 | 12 young adults who learned to juggle with three balls, compared with 12 others who did not | Grey matter increased in areas linked to the perception of movement. Three months after training stopped, it had partly decreased. |
These studies show two things: the brain changes with what we practise, and these changes need to be maintained. What is no longer used tends to fade.
Three common myths to set aside
- “We only use 10% of our brain.” This is a myth: every area of the brain has a function and is active at different times.
- “Brain-training games make you smarter.” A major scientific review showed that they mainly improve… performance on the game’s own exercises, with very little evidence of effects on everyday life (Simons et al., 2016). One exception is being studied: in older people, a specific training in processing speed, supplemented by booster sessions, was associated with fewer dementia diagnoses twenty years later; memory and reasoning training did not show this effect. It is an encouraging result, still to be confirmed (Coe et al., 2026).
- “After a certain age, it’s too late.” The brain remains capable of learning throughout life. Changes often require more time and repetition with age, and they remain possible.
What this means after trauma
Neuroplasticity has two sides. A traumatic event, or years of stress, strengthen the circuits of alarm and vigilance: the brain has learned that the world is dangerous, and it reacts quickly and strongly. This is a form of learning: the brain was trying to protect the person. To find out more: What is trauma?.
Yet what has been learned can, in part, be relearned. In people with post-traumatic stress disorder, imaging studies suggest that psychotherapy can reduce the activity of the amygdala, the “alarm detector”, and strengthen that of regions that help regulate emotions (Thomaes et al., 2014). New experiences of safety, caring relationships and repeated exercises work in the same direction. It is gradual work that takes time, and it is precisely what neuroplasticity makes possible.
What helps the brain to change
- Repeat: a new reflex is built through regular practice, step by step.
- Learn something new: a language, an instrument, a craft.
- Sleep well: sleep helps consolidate what we have learned during the day (Rasch and Born, 2013).
- Move: in older people, a year of regular aerobic exercise increased the volume of the hippocampus by about 2%, whereas it decreased in the control group (Erickson et al., 2011).
- Nurture relationships: trusting relationships are among the most fertile ground for change.
- Ease stress: chronic stress hampers learning. Exercises such as heart coherence breathing help bring the pressure down.
Need help now?
Thoughts of suicide? Contact a crisis line: 988 (US/Canada), Samaritans 116 123 (UK and Ireland), or find a local helpline at findahelpline.com. In France: 3114 (free and confidential, 24/7).
Immediate danger? Call your local emergency number: 999 in the UK, 911 in North America or 112 in the EU.
Key points
- The brain changes throughout life according to what we experience, learn and repeat.
- What is practised grows stronger; what is no longer used tends to fade.
- Brain-training games mainly improve performance on the game’s own exercises; their effects on everyday life are poorly demonstrated.
- Trauma involves learning about danger, and what has been learned can, in part, be relearned.
- Repetition, sleep, movement, relationships and easing stress all support this change.
References
- Boldrini, M. et al. (2018) 'Human hippocampal neurogenesis persists throughout aging', Cell Stem Cell, 22(4), pp. 589–599. Available at: https://doi.org/10.1016/j.stem.2018.03.015.
- Coe, N.B. et al. (2026) 'Impact of cognitive training on claims-based diagnosed dementia over 20 years: evidence from the ACTIVE study', Alzheimer's & Dementia: Translational Research & Clinical Interventions, 12(1), e70197. Available at: https://doi.org/10.1002/trc2.70197.
- Draganski, B., Gaser, C., Busch, V., Schuierer, G., Bogdahn, U. and May, A. (2004) 'Changes in grey matter induced by training', Nature, 427(6972), pp. 311–312. Available at: https://doi.org/10.1038/427311a.
- Dumitru, I. et al. (2025) 'Identification of proliferating neural progenitors in the adult human hippocampus', Science, 389(6755), pp. 58–63. Available at: https://doi.org/10.1126/science.adu9575.
- Erickson, K.I. et al. (2011) 'Exercise training increases size of hippocampus and improves memory', Proceedings of the National Academy of Sciences, 108(7), pp. 3017–3022. Available at: https://doi.org/10.1073/pnas.1015950108.
- Maguire, E.A. et al. (2000) 'Navigation-related structural change in the hippocampi of taxi drivers', Proceedings of the National Academy of Sciences, 97(8), pp. 4398–4403. Available at: https://doi.org/10.1073/pnas.070039597.
- Rasch, B. and Born, J. (2013) 'About sleep's role in memory', Physiological Reviews, 93(2), pp. 681–766. Available at: https://doi.org/10.1152/physrev.00032.2012.
- Simons, D.J. et al. (2016) 'Do "brain-training" programs work?', Psychological Science in the Public Interest, 17(3), pp. 103–186. Available at: https://doi.org/10.1177/1529100616661983.
- Sorrells, S.F. et al. (2018) 'Human hippocampal neurogenesis drops sharply in children to undetectable levels in adults', Nature, 555(7696), pp. 377–381. Available at: https://doi.org/10.1038/nature25975.
- Thomaes, K. et al. (2014) 'Can pharmacological and psychological treatment change brain structure and function in PTSD? A systematic review', Journal of Psychiatric Research, 50, pp. 1–15. Available at: https://doi.org/10.1016/j.jpsychires.2013.11.002.
- Woollett, K. and Maguire, E.A. (2011) 'Acquiring "the Knowledge" of London's layout drives structural brain changes', Current Biology, 21(24), pp. 2109–2114. Available at: https://doi.org/10.1016/j.cub.2011.11.018.
This article offers general guidance, up to date at the date of publication. It is no substitute for the advice of a doctor, who alone can make a diagnosis, or for support from a psychologist or psychotherapist.
