To drive a black cab in London, you first have to pass one of the hardest tests in the world. It’s called the Knowledge, and it means memorising every street, landmark, and route within six miles of Charing Cross. That’s roughly 25,000 streets in all. Most drivers need three to four years to do it.
When neuroscientists scanned London taxi drivers, they found their hippocampi, the brain’s memory and navigation hub, were larger than average, and the effect grew with years on the job.
To check whether learning the Knowledge caused that change, rather than big hippocampi simply drawing certain people to the work, researchers tracked trainees across their years of study. As they absorbed the Knowledge, that part of their brain physically grew.
This is neuroplasticity, and it overturns one of the oldest assumptions in science: that the adult brain is fixed. It’s not. Every time you learn something, your brain alters its own physical structure to hold it.
Learning is not filed away in the brain like a document on a hard drive. Learning is the brain rebuilding itself.
That fact is the foundation of everything an organisation does when it trains its people. If learning physically reshapes the brain, then training is not information transfer. It is brain-building, and it can be done well or badly. With this in mind, let’s start by understanding what that building actually involves.
What is Neuroplasticity?
Neuroplasticity is the brain’s ability to change its own structure and function in response to experience. Every skill you build, fact you learn and habit you form leaves a physical mark, in the connections between your neurons, and sometimes in the shape of the brain itself.
Arriving at this idea took a long time. For most of the history of neuroscience, the adult brain was assumed to be fixed, its wiring set in childhood and unchangeable thereafter.
Santiago Ramón y Cajal, the founding father of modern neuroscience, wrote in 1928 that in the adult brain “the nerve paths are something fixed, ended, immutable”. That view held for decades.
We now know that it’s wrong. As a recent review puts it, plasticity was once believed to occur only in early development, but is now understood to continue across our whole lifespan. What’s more, this neuroplasticity comes in two broad forms:
- Functional Plasticity: This is the brain’s ability to shift a job from one area to another, most dramatically when it reroutes a function around damaged tissue. It’s why some stroke survivors regain speech or movement as healthy regions take over the work of injured ones.
- Structural Plasticity: This is the brain physically changing its architecture in response to use. It involves strengthening connections, growing new ones, and pruning others away. This is the kind of plasticity that learning depends on, and where we’ll focus most of our energy.
There is one correction worth making, since it often causes confusion. Plasticity is not confined to one or two special regions. It happens throughout the brain, wherever experience makes demands on it. Nowhere is this clearer than in what the brain can do when part of it is lost.
What Happens When the Brain is Damaged?
The most dramatic proof that the brain can rewire comes not from learning but from injury. This is functional plasticity: the brain’s ability to shift a job from a damaged region to a healthy one.
After a stroke destroys the tissue controlling movement or speech, patients can regain lost abilities as neighbouring or opposite regions gradually take over the work. Indeed, brain imaging shows the activity physically relocating as recovery progresses.
The most striking case is hemispherectomy, an operation that removes or disconnects an entire half of the brain to stop severe epilepsy in children. It sounds catastrophic, yet many of these children recover remarkably well, because the remaining hemisphere reorganises to take on the work of the one that is gone.
There is a limit, and it is one this article will keep returning to: age. This wholesale reorganisation is far more complete in young children, whose brains are at their most plastic, than in adults, where recovery is slower and more partial.
For everyday learning, though, the lesson is not about injury. It is that the reorganising capacity injury reveals in its most extreme form is the very same capacity ordinary learning draws on every day.
If the brain can rebuild itself around a missing hemisphere, reshaping it through training suddenly becomes a rather modest ask.
How the Brain Physically Changes
So what actually changes when you learn? Plasticity is not one process but several, working at different scales, from the join between two cells to the growth of entirely new ones.
Connections Strengthen
The foundation is the synapse, the junction where one neuron signals the next. When two neurons fire together repeatedly, the connection between them strengthens, a principle captured in the phrase “neurons that fire together, wire together”.
This is the same synaptic strengthening that underlies memory: learning something and remembering it are, at this level, the same physical event. Repetition is not dull necessity. It’s how a pathway is reinforced until it holds.
Newer work has found a form of plasticity that works over seconds rather than milliseconds. Behavioural timescale synaptic plasticity is a single burst of activity that can tune a neuron in one shot. It’s early science, but it hints at how the brain can sometimes learn from a single, vivid experience rather than through exposure alone.
Structure Remodels
Strengthened connections add up to visible change. When volunteers learned to juggle over three months, scans showed grey matter expand in regions handling visual motion. The telling detail came next: when they stopped practising, the growth partly reversed.
The brain builds what you use and releases what you don’t, which is why the taxi drivers’ hippocampi from our earlier example grew with the Knowledge, and why unused skills fade.
Wiring Gets Insulated
The brain also speeds up its own circuits. Axons, the cables between neurons, are wrapped in a fatty sheath called myelin that makes signals travel faster. Learning a skill triggers new myelin, and when researchers blocked that process in mice, the animals could not learn the skill at all.
In humans, the myelin in a pianist’s motor pathways tracks the hours they have practised. So the brain does not only rewire. It re-insulates, laying faster cabling along the routes you use most.
New Neurons Grow
Most strikingly, the adult brain can grow entirely new neurons. In 1998, researchers found new neurons forming in the adult human hippocampus, overturning the old belief that we are born with all the neurons we will ever have.
The finding was contested for two decades, until work in 2025 identified the dividing cells behind it and largely settled the question in favour of lifelong neurogenesis.
There we have it. Four mechanisms, with a unifying theme. Experience leaves a physical trace, and the brain you use is the brain you build.
Is It Ever Too Late to Learn?
If the brain rewires itself through use, an obvious question follows: does that ability fade with age? The popular answer is that it does, and hardens into a firm belief that the brain is “fully formed” at 25 and set in its ways thereafter.
The truth is more encouraging.
Childhood does have a genuine advantage: early life contains sensitive periods, windows when the brain is especially malleable, which is why children pick up languages and accents so effortlessly. But heightened plasticity in youth does not mean we have no plasticity later in life. The brain’s capacity to change never switches off.
The evidence for adult rewiring is exactly the evidence we have already met.
- The London taxi drivers were grown adults when the Knowledge reshaped their hippocampi.
- The jugglers were university students and beyond.
- The pianists laid down new myelin through years of adult practice.
And the adult hippocampus, we now know, keeps producing new neurons into old age. None of this describes a brain that stops changing at 25.
What is true is that it can take more deliberate effort as we age. The easy, absorbent plasticity of childhood does gradually settle. But “harder” is not “impossible” and this belief can cause real damage. It leads to a fixed mindset, because the learner who thinks they are too old to change will not put in the effort that would prove them wrong.
The science is clear: the brain remains capable of rewiring for as long as you keep asking it to.
What Turns Plasticity Up and Down?
The brain does not rewire at a constant rate. Plasticity is dialled up or down by the state you are in, which is why the same hour of training can reshape one brain and barely touch another. With this in mind, here are three factors that can shift the dial:
- Attention: The brain rewires what you concentrate on, not what merely passes before you. Indeed, when researchers trained monkeys on a listening task, their auditory cortex only remapped for the sound they were paying attention to. The identical sound, ignored, changed nothing.
- Sleep: Much of the physical work of rewiring, consolidating connections and laying down myelin, happens after the learning during sleep. A well-rested brain builds. A sleep-deprived one struggles.
- Stress: Short bursts of pressure can sharpen focus, but chronic stress has a corrosive impact. Sustained high cortisol impairs the mechanisms of plasticity, weakening connections in the hippocampus and causing its neurons to retract their branches.
A workforce under relentless pressure is, quite literally, less able to learn, however good the training may be.
The practical implication is that plasticity is a property not just of the brain but of the conditions around it. Deliver identical content to two people and you can get entirely different physical results, depending on whether they are focused and rest enough for the brain to do its building work.
What Neuroplasticity Means for Workplace Learning
If learning physically rewires the brain, then training is not about transferring information. It’s about changing the structure of someone’s brain, and that reframes what good training looks like. Five principles follow directly:
- Repetition Builds the Pathway: A single exposure rarely rewires anything durably. Connections strengthen through repeated activation, so the skills that matter need to be revisited, practised and applied, not covered once and ticked off. This is why one-off training events so rarely change behaviour.
- Spacing and Sleep Do the Construction: The physical work of rewiring, consolidating connections and laying down myelin, happens over time, much of it during sleep. Learning spread across days with rest between sessions gives the brain the time it needs to build, which is the logic behind spaced repetition.
- Use it or Lose It: Remember, the jugglers’ gains reversed when they stopped practising. The brain releases what it does not use, so skills that are trained but never applied will quietly fade. Learning has to connect to the day job, or the pathway it built will get pruned away.
- Retrieval Strengthens the Circuit: Every time a learner actively recalls something, they fire and reinforce the pathway that holds it. This is why retrieval practice, testing and applying knowledge rather than rereading it, physically embeds learning more deeply than passive review.
- Old Wiring Has to be Overwritten: Learners are not blank slates. They come with existing habits and assumptions, and these are physical pathways too. Genuine change means competing with and overwriting that wiring, which takes more repetition and effort than teaching something new.
Taken together, these principles turn an abstract idea into a design brief. Training that respects how the brain rewires works with our biology. That means it should be spaced, repeated, applied, retrieved, and mindful of what it’s replacing.
Final Words
Everything in this article points to one conclusion. The brain is not a container to be filled, but a structure to be reshaped, and every piece of learning is a physical change in the tissue. Get the conditions right and your brain will rewire readily.
This is what neurogogy means: designing learning around how the brain actually rewires itself, rather than how we wish it worked. A brain that changes through repetition, consolidates during rest, strengthens through retrieval and prunes what it does not use needs learning built to match.
Training that ignores how the brain rewires does not simply underperform. It leaves the brain unchanged. And that’s the whole point of training: to build for how you’re wired.
Ready to build learning that lasts?
- Download 100 Brain Science Tips for neuroscience-backed tactics to put brain-friendly learning to work.
- Book a demo to see how the Impact Suite turns the science of neuroplasticity into training that sticks.
- Explore the Impact Suite and the neuroscience behind every feature.
