Book summary “The brain that changes itself”: summary

Introduction

You likely view your brain as a fixed biological machine that stops changing after childhood. Decades of neuroscience taught that brain damage is permanent and that mental decline with age is inevitable.

Norman Doidge shatters this dogma in The Brain That Changes Itself. He reveals that the brain is neuroplastic, meaning its physical structure and functional maps are mutable throughout your life. When you learn, recover from injury, or change your habits, your neurons actively rewire themselves.

The book explores how science overturned centuries of dogma. You will discover how sensory substitution devices let blind people see, how stroke victims recover movement through intensive training, and how mental practice alters physical structures.

How can a stroke victim regain lost functions years after an injury? What links chronic pain to bad neuroplastic habits? Can you train an aging mind to stay sharp?

1. Transforming the Senses and Overcoming Stroke

Your brain can bypass damaged pathways and repurpose alternative routes long after an injury. Sensory substitution devices and intensive rehabilitation prove that the brain can repurpose alternative pathways and recover from severe damage long after an injury. You perceive the world through your brain rather than fixed sensory receptors. Paul Bach-y-Rita demonstrated that the skin and tongue can act as data ports to feed electrical signals into the central nervous system.

Sensory Substitution and Balance

An artificial vestibular device can bypass a damaged inner ear. A construction hat equipped with an accelerometer detects head movements and transmits electrical signals to a plastic strip placed on the tongue. You can practice this approach using specific steps:

• Wear the construction hat with the accelerometer and place the electrode strip on the tongue.
• Close the eyes and allow the accelerometer to translate head tilt into electrical sensations on the tongue.
• Use the tongue sensations to monitor spatial orientation and maintain a centered posture.

Cheryl Schiltz was disabled by antibiotic-induced vestibular damage at 39 years old. She retained only 2 percent of her vestibular function and lived on a 1000 dollars a month disability check, plagued by a constant sensation of falling. Using Bach-y-Rita's tongue display device featuring 144 electrodes, she successfully stood and walked normally. Blind subjects using a 400-pound tactile-vision chair with a camera and 400 vibrating back stimulators learned to recognize objects and perceive perspective.

Late Stroke Recovery

Traditional medicine once taught that stroke recovery stops after a few months. George Bach-y-Rita disproved this dogma by rehabilitating his father Pedro, who suffered a stroke in 1959 at age 68. Pedro weighed 118 pounds during rehabilitation and recovered fully enough to return to full-time university teaching at City College in New York before dying at age 72. You can apply these graded motor exercises through practical steps:

• Begin rehabilitation by teaching the patient to crawl on kneepads along a wall.
• Turn normal life experiences and games into motor exercises, such as playing marble or coin pickup games on the floor.
• Incorporate functional tasks like washing pots by constraining erratic hand movements within a circular container for fifteen minutes clockwise and fifteen minutes counterclockwise.
• Progress through deliberate steps from crawling to kneeling, standing, walking, and relearning fine motor skills like typing finger by finger.

Edward Taub developed constraint-induced movement therapy to overcome learned nonuse in stroke survivors. A shrunken brain map for an affected arm can double in size after intensive therapy. About 80 percent of stroke patients lose arm function and can improve substantially with CI therapy. You can apply these protocols using specific techniques:

• Wear a mitt and sling on the good arm for 90 percent of waking hours.
• Perform ten to twelve incremental tasks a day, repeating each task ten times.
• Use the behavioral technique of shaping to mold behavior in very small steps.
• Progress from simple gestures to more complex functional tasks without accepting the word can't.

Nicole von Ruden was paralyzed on her right side by radiation for a brain stem glioma. She wore a mitt on her good hand and performed shaping tasks like placing poker chips in a slit, allowing her to live alone, drive, and return to work. Jeremiah Andrews suffered a stroke at age seven and fell 150 times a year in his forties. He underwent CI therapy decades later, reduced his falls to seven per year, and regained the ability to write his name with his right hand.

2. Brain Maps and Competitive Plasticity

Brain maps are driven by competition for cortical real estate under the principle of use it or lose it, allowing skills and practice to reshape neural topography.

Norman M. Doidge explains that brain maps are dynamic, variable, and capable of reorganizing throughout adult life based on experience. Using microelectrodes for micromapping, Michael Merzenich proved that sensory and motor brain maps change continuously. You possess 100 billion adult human neurons, and a 1 to 2 millimeter strip of exposed cerebral cortex can be mapped with 500 microelectrode insertions for a single hand map.

Merzenich and his colleagues micromapped the hand regions in monkey brains, severed peripheral nerves, and discovered that the brain maps reorganized themselves to compensate for the lost input rather than remaining permanently chaotic. When peripheral nerves are cut or a body part is amputated, adjacent nerves take over the unused map space. This competitive nature explains why breaking bad habits or learning a second language later in life is extremely difficult, as the mother tongue or established habits heavily dominate available map space. Humans and monkeys share 3 main nerves in their hands: radial, median, and ulnar.

Cortical Reorganization

By linking Georges Luria's localization of brain functions with Mark Rosenzweig's evidence of neuroplasticity, Barbara Arrowsmith Young invented rigorous mental exercises that successfully strengthened her weakest cognitive functions. Instead of using compensations, she isolated her weakest function—relating symbols—and designed intense mental exercises.

Barbara created an exercise involving hundreds of cards picturing clock faces showing different times, checking the backs for answers, and turning hands on a real clock to understand why the hour hand is positioned three-quarters of the way to the next number at 2:45. You can apply similar methods at the Arrowsmith School, which uses targeted computer and manual exercises to strengthen specific weak brain areas in children and adults. Applicants undergo up to forty hours of assessments to determine precisely which brain functions are weak.

Students at the school follow specific steps:

• Take a deck of cards picturing clock faces showing different times with correct answers on the back.
• Shuffle the cards so answers cannot be memorized.
• Turn up a card and attempt to tell the time as fast as possible.
• Check the answer on the back and move immediately to the next card.
• Spend hours turning the hands of a real clock to understand the spatial relationships of the hands when failing an item.
• Add hands for seconds and sixtieths of a second once initial answers are mastered.
• Work at computer exercises reading complex ten-handed clocks with divisions for minutes, hours, seconds, days, months, and years until getting enough answers right to progress.
• Study unfamiliar shapes of Urdu and Persian letters to quickly recognize alien shapes and strengthen visual memory.
• Wear an eye patch on the left eye to force visual input into the right eye and opposite brain hemisphere.
• Trace intricate lines, squiggles, and Chinese letters with pens to stimulate neurons in the weakened premotor area.
• Listen to CDs and memorize poems through rote memorization to improve weak auditory memory.

A boy with a weak premotor cortex struggled to convert thoughts into speech, writing, and reading because his brain easily overloaded when stringing movements together. After tracing complex lines at the Arrowsmith School, his reading, writing, and speech dramatically improved.

Overcoming Learning Disabilities

Learning and language disabilities often stem from slow temporal processing where fast parts of speech are processed too slowly, but targeted computerized exercises can rapidly normalize brain function.

Children with language impairments have neurons that take 3 times slower neuron recovery, or a 90-millisecond delay compared to the 30-millisecond normal neuron recovery time, resulting in muddy signals. The author notes that 80 percent of language-impaired children suffer from this condition, which produces muddy in, muddy out processing problems. The Fast ForWord program uses computer games with slowed-down speech sounds that gradually speed up, accompanied by rewards that release dopamine and acetylcholine to consolidate map changes.

Seven-year-old Willy Arbor suffered from an auditory-processing disorder that confused similar-sounding words and overloaded his memory. He completed the Fast ForWord program across 500 children studied across 35 sites and gained 30 to 60 hours or 1.8 years of language development gained in 6 weeks, which improved his grades and social comprehension.

You can engage with auditory exercises designed around these principles:

• Catch a flying cow with the computer cursor and hold it while listening to a moo sound.
• Release the cow when the length of the moo sound changes subtly.
• Identify easily confused consonant-vowel combinations like ba and da at progressively faster speeds.
• Hear and track faster frequency glides that sweep up.
• Remember and match sounds across a series of structured exercises.

Age-related cognitive decline is largely caused by the neglect of attentional and plasticity systems rather than inevitable neuronal death. As you age, processing speed slows down, creating fuzzy engrams and signal-noise problems because the nucleus basalis is neglected, exposing you to a 47 percent chance of Alzheimer disease by age eighty-five. Posit Science developed computerized brain exercises that restore processing speed, strengthen signals, and stimulate acetylcholine and dopamine production.

Adults aged sixty to eighty-seven trained on auditory memory programs for forty to fifty hours of total exercise time in studies, improving their test scores from the typical seventy-year-old level to a youthful forty-to-sixty-year-old range, with PET scans confirming arrested metabolic decline and achieving 10 to 25 years of memory clock reversal achieved by participants.

3. The Dark Side of Plasticity and Pain

The same neuroplastic mechanisms that drive learning can lock the brain into chronic pain, phantom limbs, and obsessive-compulsive disorders.

Neuroplasticity is not always beneficial. When a limb is amputated, its corresponding brain map stops receiving sensory input and starves. Neighboring brain maps, such as the facial map which sits next to the hand map in the Penfield homunculus, sprout new connections and invade the vacant map area. As a result, stimulating a neighboring body part causes the brain to register signals in both areas.

95 percent of amputees experience chronic phantom pain that often persists for a lifetime. When V. S. Ramachandran stroked the cheek and upper lip of an amputee named Tom Sorenson with a Q-tip, Tom felt the touch on his face and simultaneously felt it in his phantom hand and missing index finger.

Phantom Limbs and Mirror Boxes

The mirror box creates a visual illusion that fools the brain into believing a missing or paralyzed limb is moving, allowing patients to unlearn paralysis and eliminate phantom pain. The mirror box uses a vertical mirror placed between two compartments. By putting the good hand in and looking at its reflection, the patient sees a resurrected image of the missing limb.

Philip Martinez was going forty-five miles per hour speed when hurled from his motorcycle, leaving him with a paralyzed and painful phantom arm. Philip spent ten minutes a day practice time using the mirror box. After four weeks of mirror box use, Philip's phantom arm and pain permanently vanished.

You can perform this treatment yourself with simple steps:

• Put the good hand through the front hole and into the right compartment of the mirror box.
• Imagine putting the phantom hand into the left compartment.
• Look at the mirror image reflection of the good hand, which appears to be the amputated hand.
• Move the good hand back and forth while watching the reflection to make the resurrected hand appear to move.

In disorders like reflex sympathetic dystrophy, minor injuries cause a limb to become so painful that you guard it against movement. Over time, the brain wires the motor command to move into the pain network, so that simply attempting to move triggers immediate agony even after the original injury has completely healed. Patients with chronic pain syndromes lasting less than two months recovered fully using mirror box therapy, while those suffering for more than two years failed to improve because their motor maps had wasted away from prolonged disuse.

Obsessive-Compulsive Disorder and Brain Lock

Behavioral self-treatment changes brain activation and normalizes the caudate nucleus in obsessive-compulsive disorder by reframing urges as false brain messages. Jeffrey Schwartz demonstrated that the caudate nucleus acts as an automatic transmission for thoughts and worries. Some children developed sudden OCD after strep throat infections because immune antibodies attacked their caudate nuclei, causing them to swell 24 percent larger than normal.

Treating OCD through neuroplasticity requires you to manually shift gears by relabeling the obsession and refocusing on a positive activity. You must recognize that distress is a symptom of a faulty brain circuit rather than a real external threat, and then actively redirect your attention to grow new competing neural circuits.

You can apply the brain lock framework using these four steps:

• Relabel what is happening by realizing the experience is an episode of OCD rather than a real threat like germs or AIDS.
• Remind yourself that the attack persists due to a faulty brain circuit.
• Refocus on a positive, wholesome, ideally pleasure-giving activity the moment you become aware of an OCD attack.
• Change the channel to some new activity for fifteen to thirty minutes when an OCD symptom occurs.

4. Imagination, Aging, and Cultural Plasticity

Mental rehearsal alters physical structures just like physical practice, while environmental enrichment and neurogenesis protect the aging brain.

Imagining an action activates many of the same brain regions as actually performing it, strengthening neuronal connections and motor programs. Mental practice prepares the brain efficiently, allowing you to reach higher accuracy levels with minimal physical execution.

Alvaro Pascual-Leone taught non-pianists a finger sequence. A group doing only mental practice for two hours a day for five days achieved motor changes and accuracy levels comparable to actual players on their third day.

You can apply mental rehearsal using these two steps:

• Sit in front of an electric piano keyboard two hours a day for five days.
• Imagine both playing a specific sequence of notes and hearing it played.

Imagining physical muscle contractions activates motor programs and can significantly increase actual physical strength without bodily movement. During imaginary contractions, the motor neurons responsible for programming movement sequences are activated and strengthened. This mental programming improves neural drive and force generation when muscles are subsequently contracted.

Guang Yue and Kelly Cole found that subjects who only imagined exercising a finger muscle for four weeks increased their strength by 22 percent, compared to 30 percent for those who exercised physically.

The Power of Mental Practice

You can strengthen muscles through visualization using these three steps:

• Imagine performing fifteen maximal contractions of a finger muscle.
• Rest for twenty seconds between each imagined contraction.
• Imagine a voice shouting harder instructions during the visualization.

Vision is so dominant that it normally suppresses other inputs in the visual cortex. Blocking light forces the visual cortex to quickly recruit unused processing power for touch and sound, demonstrating that brain regions are not rigidly locked to a single sense.

Alvaro Pascual-Leone blindfolded sighted subjects for five days and found that their visual cortices began processing tactile and auditory signals in as few as two days, accompanied by complex visual hallucinations.

You can enter the school of darkness using these two steps:

• Apply an impermeable blindfold or roadblock to eliminate all light.
• Maintain the sensory restriction for several days to trigger cortical reorganization.

Adult Neurogenesis and Aging

The human brain is capable of generating new neurons throughout life, a process known as neurogenesis. Contrary to the long-held dogma established by Santiago Ramon y Cajal that the adult brain is immutable and incapable of regeneration, Peter Eriksson and Rusty Gage discovered living neuronal stem cells in the hippocampus of human patients using a BrdU marker.

Peter Eriksson and Rusty Gage injected terminally ill patients with a marker called BrdU and later found newly formed baby neurons in their hippocampi after they died.

Physical exercise creates new stem cells, while cognitive learning helps those new cells survive and last longer. Research on mice by Gerd Kempermann and Henriette van Praag showed that physical activity like running or fast walking increases the proliferation of new hippocampal neurons, while learning to use toys and navigate new environments extends the lifespan of those newly created cells.

Gerd Kempermann raised aging mice in enriched environments with toys and running wheels for forty-five days, resulting in a 15 percent increase in hippocampal volume and forty thousand new neurons.

Consistent physical movement and cardiovascular exercise strengthen blood vessels supplying the brain and stimulate growth factors necessary for plastic change. Walking, cycling, or any natural movement of limbs stimulates the production of BDNF and supplies the brain with essential oxygen and energy, while avoiding monotony that undermines attentional systems.

Dr. Stanley Karansky combined auditory memory computer exercises with muscle exercises on CYBEX machines and thirty-minute exercise bicycle workouts three times a week.

You can protect your brain using these three steps:

• Do muscle exercises three times a week on CYBEX machines.
• Follow muscle exercises with a thirty-to thirty-five-minute workout on an exercise bicycle.
• Engage in consistent natural movement of the limbs such as walking at a good pace.

Every sustained cultural activity reshapes the brain's physical structure, creating a culturally modified brain. Unlike the view that genetics alone produce culture and that the brain has been stuck since the Pleistocene age, neuroplasticity proves that learning complex cultural skills such as reading, music, or navigation alters neural circuits and brain maps.

London taxi drivers who spend years navigating the city have a larger volume of the hippocampus compared to non-drivers.

10 Key Ideas

1. Sensory substitution devices and intensive rehabilitation prove that the brain can repurpose alternative pathways and recover from severe damage long after an injury.
2. Brain maps are driven by competition for cortical real estate under the principle of use it or lose it, allowing skills and practice to reshape neural topography.
3. Learning and language disabilities often stem from slow temporal processing where fast parts of speech are processed too slowly, but targeted computerized exercises can rapidly normalize brain function.
4. The same neuroplastic mechanisms that drive learning can lock the brain into chronic pain, phantom limbs, and obsessive-compulsive disorders.
5. The mirror box creates a visual illusion that fools the brain into believing a missing or paralyzed limb is moving, allowing patients to unlearn paralysis and eliminate phantom pain.
6. Behavioral self-treatment changes brain activation and normalizes the caudate nucleus in obsessive-compulsive disorder by reframing urges as false brain messages.
7. Mental rehearsal alters physical structures just like physical practice, while environmental enrichment and neurogenesis protect the aging brain.
8. Imagining physical muscle contractions activates motor programs and can significantly increase actual physical strength without bodily movement.
9. Physical exercise creates new stem cells, while cognitive learning helps those new cells survive and last longer.
10. Consistent physical movement and cardiovascular exercise strengthen blood vessels supplying the brain and stimulate growth factors necessary for plastic change.