Neuroplasticity: How the Brain Changes and Adapts

Neuroplasticity is the brain's ability to change its structure, connections and function in response to experience. Every time you learn a fact, practice a skill or recover from an injury, networks of neurons adjust: some connections strengthen, others weaken, new ones form and unused ones are pruned. Plasticity is strongest in childhood, but it continues throughout adult life.

For much of the twentieth century, many scientists believed the adult brain was essentially fixed once development was complete. A series of discoveries from the 1960s onward overturned that view, showing that experience reshapes the brain at every age. At the same time, "neuroplasticity" has become a popular buzzword attached to products and promises that the science does not support. This page covers both what is known and where the claims outrun the evidence.

Understanding Neuroplasticity

Definition and core concepts

Neuroplasticity is an umbrella term. It covers changes at many levels, from molecules inside a single synapse to the reorganization of whole brain regions. Researchers often describe two broad kinds:

• Structural plasticity: physical changes such as new dendritic spines, growth or pruning of axon branches, changes in the myelin that insulates nerve fibers, and, in some brain regions, the addition of new neurons.
• Functional plasticity: changes in how existing networks work, such as a synapse becoming more efficient, or another brain area taking over a function after damage.

William Greenough and colleagues (1987) drew another useful distinction. Experience-expectant plasticity relies on experiences nearly every member of a species will have, such as seeing patterned light or hearing speech in infancy, and is tied to sensitive periods. Experience-dependent plasticity reflects experiences unique to each person, such as learning to play the violin, and continues across life.

A brief history

Core principles from rehabilitation research

Rehabilitation scientists have summarized several principles that describe when experience-dependent plasticity is most likely to occur. Among the best supported:

• Use it or lose it: networks that are not used tend to weaken.
• Specificity: the brain changes in ways specific to what is practiced, which is why training one task rarely improves unrelated abilities.
• Repetition and intensity: lasting change usually requires sustained, effortful practice.
• Salience: practice that is meaningful and attention-grabbing tends to drive more change.
• Age matters: plasticity is easier in younger brains but persists in older ones.
• Interference: plasticity in one direction can make other learning harder, as when a compensatory habit after injury blocks recovery of the original skill.

Types and Mechanisms of Neuroplasticity

Synaptic plasticity

The best-understood form of plasticity happens at synapses, the junctions where neurons communicate. In long-term potentiation (LTP), repeated stimulation makes a synapse respond more strongly for hours, days or longer; in long-term depression (LTD), a synapse weakens. These processes rely on receptors for the neurotransmitter glutamate and on changes in gene expression and protein synthesis. LTP in the hippocampus is widely regarded as one of the cellular bases of learning and memory, a topic explored in memory psychology.

Structural changes

Learning is associated with the growth of new dendritic spines, the small protrusions that receive synaptic input, and with pruning of unused ones. White matter also changes: myelin, the fatty insulation around axons, can be adjusted by activity, which may help tune the timing of signals between brain regions. Growth factors such as brain-derived neurotrophic factor (BDNF) support these processes.

Map reorganization

The cortex contains "maps" of the body and senses. These maps can shift. After a finger is lost, the area that used to represent it can begin responding to neighboring fingers. In people who are blind from an early age, parts of the visual cortex become active during Braille reading, an example of cross-modal plasticity. Violinists and other string players show enlarged cortical representations of the fingers of the left hand, which does the fine fingering work.

Adult neurogenesis: an open question

New neurons are clearly produced throughout life in some animals, particularly in the hippocampus. In humans the picture is contested. Some studies, including a 2013 analysis of carbon-14 in human brain tissue, estimated that hundreds of new neurons are added to the hippocampus each day in adults. A 2018 study found new neurons to be extremely rare or undetectable in adult human hippocampi, while a 2019 study using different tissue methods found them into old age. Until this is resolved, claims that any activity "grows new brain cells" in humans should be treated with caution.

Developmental versus adult plasticity

Childhood is marked by rapid growth of connections followed by extensive pruning, and by sensitive periods when particular experiences have outsized effects. Hubel and Wiesel's work showed that if one eye is deprived of vision during a sensitive period in kittens, the visual cortex permanently favors the other eye; a similar logic explains why childhood amblyopia ("lazy eye") is treated early. Language shows a comparable pattern, discussed in our page on language acquisition. Adult plasticity is real but more effortful, and usually refines existing circuits rather than building new systems from scratch.

Landmark Studies in Humans

Several studies are cited so often that they are worth knowing in detail, including what they do and do not show.

• London taxi drivers (2000): Eleanor Maguire and colleagues found that licensed London taxi drivers, who must memorize the city's complex street layout, had a larger posterior hippocampus than control participants, and the size correlated with years of driving. A later longitudinal study found that trainees who qualified showed growth over the training period, which strengthens the case that the training caused the change. Drivers also had a smaller anterior hippocampus, a reminder that plasticity involves trade-offs.
• Juggling (2004): Bogdan Draganski and colleagues found that people who learned to juggle over three months showed temporary increases in gray matter in visual motion areas, which partly reversed after they stopped practicing.
• Meditation (2011 onward): An influential study by Britta Hölzel and colleagues reported gray matter changes after an eight-week mindfulness course. However, a larger and more rigorous 2022 randomized trial did not find structural brain changes after similar training, so claims that meditation "grows" particular brain regions in weeks remain uncertain.

Together these studies show that the adult brain responds to sustained, specific experience. They also show the limits of the method: MRI measures of "gray matter" are indirect and can be influenced by many factors, and small studies often produce effects that larger ones do not confirm.

Factors That Influence Plasticity

Factors associated with healthy plasticity

• Physical activity: aerobic exercise is associated with higher levels of BDNF in animal and human studies, and some trials in older adults have found modest benefits for memory and hippocampal volume. Our page on exercise psychology discusses the wider evidence.
• Learning demanding skills: sustained practice at something new and challenging, such as a language, an instrument or a complex craft, engages the kind of focused, repeated effort that drives change.
• Sleep: sleep supports the consolidation of newly learned material and the balancing of synaptic strength; see sleep hygiene for general background.
• Social engagement: complex social interaction is cognitively demanding, and social isolation is associated with poorer cognitive health in later life.

Factors associated with reduced plasticity

Chronic stress, sleep deprivation, heavy alcohol use and some illnesses are associated with reduced markers of plasticity in animal and human research. Prolonged high levels of stress hormones, for example, can affect the hippocampus in animal studies. These are associations studied at the population level; they do not mean any individual's brain is damaged by ordinary stress. For background, see stress management.

Age-related changes

Brain volume gradually declines with age on average, processing speed slows, and some forms of plasticity become less efficient. Yet older adults continue to learn new skills, and accumulated knowledge often remains stable or grows. The idea of cognitive reserve describes how education, mentally demanding work and other life experiences may help some people maintain function despite age-related brain changes.

Neuroplasticity and Mental Health

Researchers increasingly describe mental health conditions partly in terms of how brain networks adapt. Long-standing patterns of fear, rumination or habitual behavior involve learned associations that are, in a sense, products of plasticity. Psychological therapies such as cognitive behavioral therapy and exposure-based approaches involve new learning, and imaging studies have reported changes in brain activity after successful treatment, although findings vary and are not used to guide individual care.

Some studies have linked depression with differences in hippocampal volume and with lower levels of BDNF, and researchers are investigating whether various treatments work partly by influencing plasticity. This is an active research area rather than settled science. Decisions about treatment, including any medication, are made with a doctor or mental health professional, and anyone struggling with their mental health should seek qualified support. If you are in crisis, see our crisis resources.

Injury, Rehabilitation and Recovery

Stroke rehabilitation

After a stroke, some recovery occurs spontaneously as swelling subsides and surviving tissue resumes function, with the fastest gains usually in the first months. Rehabilitation aims to harness plasticity through intensive, task-specific practice. Constraint-induced movement therapy, developed by Edward Taub, restricts use of the stronger arm so that the weaker one must be practiced; a multi-site trial published in 2006 found improvements in arm function for selected patients. Recovery can continue for years in some people, though progress varies widely.

Traumatic brain injury

After a traumatic brain injury, rehabilitation may combine practice of impaired skills with compensatory strategies, such as memory aids. Clinicians use neuropsychological testing to map which abilities are affected and to track change over time, and the field of neuropsychology studies how brain injury affects thinking and behavior. Children's brains often show greater capacity to reorganize after early injury, a topic covered in child neuropsychology, although early injury can also disrupt development in ways that appear later.

Phantom limbs and mirror therapy

After amputation, many people continue to feel the missing limb, sometimes painfully. V. S. Ramachandran's work in the 1990s linked some of these sensations to remapping in the sensory cortex and popularized mirror therapy, in which a mirror creates the visual illusion of the missing limb moving. Evidence for mirror therapy is mixed but suggests it may help some people.

When plasticity works against us

Plasticity is not always helpful. In some forms of chronic pain, the nervous system becomes more sensitive, so that pain persists or spreads beyond the original injury, a process called central sensitization. Tinnitus and some movement disorders in musicians are also thought to involve maladaptive plasticity. Our page on chronic pain psychology describes how psychological approaches are used alongside medical care.

Neuroplasticity and Neuropsychological Testing

The two terms are sometimes confused because both involve the brain and thinking skills, but they are different things.

The two connect in practice: repeated neuropsychological assessments can show improvement in specific skills after injury, which partly reflects the brain's plasticity. Testing is ordered and interpreted by qualified professionals; online quizzes cannot substitute for it. For a fuller explanation of what an assessment involves, see our guide to neuropsychological testing.

What Helps, and What Is Overhyped

Brain-training games

Commercial brain-training programs promise sharper memory and attention. A comprehensive 2016 review by Daniel Simons and colleagues concluded that training reliably improves performance on the trained tasks and closely related ones, but there is little good evidence of transfer to everyday cognitive performance. In 2016 the US Federal Trade Commission also took action against one major brain-training company over unsupported advertising claims.

Learning real skills

Learning complex, real-world skills engages attention, memory, motor control and emotion together and is consistent with what is known about how plasticity works. The benefits are mainly the skill itself; whether such learning protects against later cognitive decline is still being studied.

Lifestyle and brain health

The 2024 report of the Lancet Commission on dementia identified 14 potentially modifiable risk factors across life, including less education in early life, hearing loss, physical inactivity, high blood pressure, smoking, social isolation and others, and estimated that a substantial share of dementia cases worldwide might in theory be delayed or prevented by addressing them. These are population-level estimates, not guarantees for any individual. Our pages on cognitive decline and dementia provide more background.

Common myths

• "You can rewire your brain in 21 days." Lasting change usually takes sustained practice over months, and timelines vary.
• "Plasticity means anything can be fixed." Some injuries and conditions cause lasting effects despite intensive rehabilitation.
• "Novelty alone builds the brain." Small daily novelties, such as taking a new route, are fine, but there is little evidence they produce meaningful brain change on their own.
• "We only use 10% of our brain." Imaging shows activity across the whole brain; this myth is unrelated to plasticity.

Learning, Memory and Neuroplasticity

Every lasting memory involves some change in the brain. Newly learned information is initially fragile and is stabilized through consolidation, a process that sleep supports. When a memory is recalled it can become temporarily changeable again, a phenomenon called reconsolidation.

Research on learning offers practical lessons consistent with plasticity. Spaced practice beats cramming; testing yourself strengthens memory more than rereading; and mixing different types of problems (interleaving) improves the ability to choose the right approach. These findings come from cognitive psychology and are covered in our pages on the psychology of learning and metacognition. Popular ideas such as matching teaching to a student's "learning style" are not supported by evidence.

Belief in plasticity also matters for motivation. Teaching students that ability can grow with effort is the basis of growth mindset interventions, although large studies suggest their effects on grades are small and concentrated in particular groups.

Future Directions

Researchers are working to understand how to open and close windows of heightened plasticity safely, for example to improve recovery after stroke. Non-invasive brain stimulation methods such as transcranial magnetic stimulation are being tested alongside rehabilitation, brain-computer interfaces are helping some people with paralysis control devices, and the debate over adult human neurogenesis continues. Each area raises practical and ethical questions, including how to distinguish genuine treatment advances from commercial hype.

Summary

Neuroplasticity is one of the most important ideas in modern neuroscience: the brain is shaped by experience throughout life. It explains how we learn, how children's brains are tuned by their environments, and how people can regain abilities after injury. But plasticity is gradual, specific and sometimes unhelpful, and it is not a promise that any desired change is possible with the right product or routine. The most reliable messages from the research are modest ones: sustained practice changes the trained skill, physical and social activity support brain health, and recovery after injury is real but varies from person to person.