46 pages • 1 hour read
Norman DoidgeThe Brain That Changes Itself: Stories of Personal Triumph from the Frontiers of Brain Science
Nonfiction | Book | Adult | Published in 2007A modern alternative to SparkNotes and CliffsNotes, SuperSummary offers high-quality Study Guides with detailed chapter summaries and analysis of major themes, characters, and more.
Summary
Background
Chapter Summaries & Analyses
Key Figures
Themes
Index of Terms
Important Quotes
Essay Topics
Tools
BetaChapters 5-8Chapter Summaries & Analyses
Chapter 5 Summary: “Midnight Resurrections”
Chapter 5 explores the extent to which the brain is plastic by observing cases where people were treated for long-term paralysis—focusing on the work of neurologist Edward Taub. It begins with the case of eye surgeon Michael Bernstein, who suffered a debilitating stroke at the age of 54, which damaged his motor cortex on the right hemisphere and paralyzed the left side of his body. Bernstein did not fully recover in typical poststroke rehabilitation, which lasts about six weeks. For example, he could not walk without a cane or make a pincer motion with his left thumb and first finger. It was only during his time at the Taub Therapy Clinic that he fully recovered his motor functions.
The Taub Therapy Clinic uses constraint-induced movement therapy (CI) to help stroke patients recover their motor functions. It creates training programs that take advantage of neuroplasticity to help the brain rewire itself efficiently. Prior to Taub, it was believed patients who suffered strokes and became paralyzed would never recover their motor functions. Behaviorism is a theory that dismissed the effect of mind on body, framing humans as largely passive creatures responding to outside stimuli. For example, the knee reflex is independent of the mind, as the sensory receptors in the area send a signal to the spine, which sends an impulse back to make the muscles of the knee contract—all without passing through the brain.
Behaviorism was further solidified through the work of Nobel Prize winner and neuroscientist Sir Charles Sherrington. He invented deafferentation, a surgical procedure that involves cutting nerves in a specific part of the body so it can no longer send signals to the spine and brain. This process also prevents movement and feeling in that part of the body. After testing this procedure on a monkey’s arm, Sherrington’s team was surprised that the monkey could not move his arm, even though they only cut sensory nerves (which detect feeling), not afferent nerves (which control movement). Thus, certain scientists concluded all movement is a system of reflex independent from the brain’s control, and paralysis, especially long-term paralysis, cannot be cured.
However, Taub’s research on deafferentation went further. He realized the monkey might not have used his deafferented arm because it was simply easier to use his unaffected arm to accomplish tasks. To test this theory, he put the monkey’s unaffected arm in a cast, and soon, the monkey learned to control his deafferented arm. Later, Taub deafferented both arms, and the monkey relearned to control both. This gave him hope that paralysis could be treated with forced use of limbs. There is a neurological basis to explain these results: Preventing the movement of an unaffected arm or deafferenting both arms creates space in the brain map which was previously used to receiving and processing signals from the unaffected arm. This new space can thus be allocated to decoding faint signals from the deafferented limb. Taub realized he could help people with long-term paralysis if he created a training program that addressed nonuse.
Taub coined a training style called “shaping,” which involves modifying behavior in incremental steps and rewarding them. For example, monkeys that made any gesture toward using a deafferented limb were heavily rewarded. Then, as they progressed, they were rewarded for completing harder tasks. The Taub Therapy Clinic has since proven that shaping and creating map space by restricting functional limbs can help patients who have been paralyzed for decades learn to move again. However, Taub became infamous in popular memory because Alex Pacheco, the president of People for the Ethical Treatment of Animals (PETA)—a militant organization against the cruel treatment of animals—denounced his testing on monkeys. Doidge argues that while the surgical procedure of deafferentation is not painful, the monkeys who lost sensation in their arms often injured themselves by accidentally bumping into things. Pacheco photographed Taub’s lab while he was away on vacation, stole the monkeys, and leaked information to the press in what would later be remembered as the Silver Spring monkeys case. Fearing scrutiny of their own animal testing, the National Institutes of Health (NIH) turned against Taub, painting him as a bad case among the otherwise ethical scientific community.
Over the next decade, Taub continually defended himself in court, and proved PETA’s photographs of test monkeys in their own feces were likely fabricated or posed. Since PETA removed the test monkeys, there was no way to prove Taub’s guilt. Eventually, the NIH retracted their initial stance and defended Taub, who was exonerated in a unanimous ruling. Although he won the case, his reputation was ruined in the public eye, and he could no longer resume his research. Thus, Taub pursued rehabilitation: The training program at the Taub Therapy Clinic involves doing physical tasks, such as wiping tables, tracing letters, and stretching rubber bands in a mimicry of normal daily tasks. Sometimes, patients’ functional limbs are restricted to create more brain space for paralyzed limbs. Therapy sessions last six hours (with breaks) for 10 to 15 uninterrupted days. Patients like Jeremiah Andrews, who became paralyzed 40 years ago, regained enough motor function to lead normal lives again.
A decade after the PETA debacle, neuroscientist Mortimer Mishkin managed to track some of the deafferented monkeys from Taub’s lab. Mishkin inserted electrodes in their brains and was amazed to find their brain maps fired when he stroked their faces. This means the neurons in their brains were capable of massive reorganization; the previous theory that neurons could only grow 1-2 millimeters to compensate for losses in adjacent areas was false. In fact, the neurons in Taub’s deafferented monkeys grew over 14 millimeters. Again, due to various biases, scientists underestimated the extent of neuroplasticity.
Chapter 6 Summary: “Brain Lock Unlocked”
Chapter 6 observes how neuroplasticity exercises can help patients with obsessive-compulsive disorder (OCD). Neuroscientist Jeffrey M. Schwartz developed a psychotherapy program after contrasting the brains of people with and without OCD. He realized the fundamental difference between the two groups is that those with OCD are incapable of moving on after their anxiety is triggered; their brains hyperfocus on issues and amplify them. There are three parts of the brain involved with obsession: The orbital frontal cortex detects a mistake, the cingulate gyrus triggers anxiety to correct the mistake, and the caudate nucleus helps the brain move from one thought to the next once the problem is solved. Patients with disruptive OCD display hyperactivity in all three regions, which amplifies their anxiety, realistic or otherwise.
Schwartz developed a neuroplasticity-based method to unlock the orbital frontal cortex from the cingulate gyrus, so specific triggers no longer lead to anxiety. Then, he decreases activity in the caudate nucleus by teaching patients to focus on positive thoughts. Patients are asked to relabel experiences by understanding their anxiety attacks are triggered by OCD, not a phobia. This encourages a degree of separation between experiences and themselves. If they cannot redirect their thoughts, they are asked to physically move on to another task. If this change in thought or action brings pleasure, the body will release dopamine. Schwartz’s therapy helps grow new brain circuits and solidify them: It helps OCD patients learn to not give in to obsessions, rather than preventing anxiety altogether. Over time, this therapy, used in combination with medication, proved successful even in severe cases of OCD.
Chapter 7 Summary: “Pain”
Chapter 7 discusses how neuroplasticity can sometimes cause suffering, as is the case with phantom pain. It follows the work of India-born neurologist V. S. Ramachandran, who is famous for his use of simple tools and understanding of neuroplasticity to treat otherwise untreatable pain. He prefers simple tools over complicated machinery because he believes too much distance between raw data and final conclusions can lead to false interpretations; likewise, he is skeptical of large scientific gatherings, as they often work as echo chambers. This chapter analyzes how Ramachandran uses imagination and a mirror box to help reconfigure amputees’ brains.
Pain is created by the brain to alert an organism that a part of it might be in danger. Neuroscientists Ronald Melzack and Patrick Wall posited the “gate control theory of pain,” which argues damaged body tissue sends a signal to the brain to trigger pain; however, this signal must pass through several “gates,” starting in the spinal cord, before reaching the brain, and at any point, the brain can prevent the gates from opening. If a signal is blocked, the organism feels no pain, even if it can see their damaged tissue: In Ramachandran’s words, “pain is an opinion on the organism’s state of health rather than a mere reflexive response to injury” (192). This is why people can feel pain in limbs that do not exist anymore. Phantom pain is also called neuropathic pain, which means it only exists in the brain as the result of false alarms. Ramachandran became interested in this topic after reading about Edward Taub’s Silver Spring monkeys, whose arm-related brain maps reallocated to respond to facial sensations. He suspected the same brain reconfiguration could occur in amputees who lost their arms—and successfully tested this theory with a patient whose missing arm felt “itchy,” by stroking his cheek. According to the law of competition, when people lose sensation in an area of their body, the brain area dedicated to these signals becomes free and can be reallocated to neighboring areas. Thus, women who have mastectomies can still experience sexual excitement in their ears, clavicles, and sternums; foot fetishes might be common because the brain map for the genitals is adjacent to the brain map for the feet.
Ramachandran also posits that people can feel pain in severed limbs because when the brain sends a signal to move a limb, it expects a reply from the limb. When a limb is prevented from sending a return signal, the brain could interpret this as the limb having been frozen in constant distress. Ramachandran believed that to relieve these phantom pains, he needed to fool the brain into believing it was receiving a return signal from the phantom limb. Thus, he invented a mirror box with two compartments and a mirror between them. A patient inserts their arm into the corresponding side of the box and imagines doing the same on the other side with their phantom limb. Then the patient must look at the mirror and move their arm while pretending the image they see is their severed arm. After practicing with the mirror box, Philip, one of Ramachandran’s first patients, reported his phantom limb had unfrozen. In other words, he had successfully tricked his brain with a mirror image, body image.
Ramachandran distinguishes body image from mental constructs and the material body. A mental construct is imaginary whereas the material body exists in the physical world. Body image is flexible and can be projected onto anything if done correctly. To illustrate this, Ramachandran asked Doidge to hide his right hand under a table. Using one hand, Ramachandran began stroking the table; at the same time, his other hand stroked Doidge’s hidden right hand. He then tapped the table and Doidge’s hidden right hand. Soon, Doidge stopped feeling his right hand, and his body image extended to the table. When Ramachandran hit the table—now an extension of Doidge’s body—with a hammer, Doidge reflexively felt stress because his brain expected to feel pain.
Australian scientist G. L. Moseley used the same principle of imagination to help patients with type 1 chronic pain. This condition happens when a limb suffers a minor injury but triggers a disproportionate response in the brain. People often freeze when they feel pain because this reflex, called “guarding,” is intended to prevent the body from aggravating the injury. People with type 1 chronic pain are stuck in a loop where any attempt to move their limb triggers intense discomfort because their brain still believes the limb is in danger. Because these patients often cannot use the mirror box, Moseley instead asks them to study pictures of their affected limbs for 45 minutes per day in three 15-minute increments, an exercise that activates the motor cortex in the brain. After 12 weeks, half of his patients reported either a decrease in or loss of chronic pain. Overall, these successes showcase how some pain can be treated with the power of the mind.
Chapter 8 Summary: “Imagination”
Chapter 8 explores Alvaro Pascual-Leone’s groundbreaking work on transcranial magnetic stimulation (TMS). Pascal-Leone is the chief of the Beth Israel Deaconess Medical Center at Harvard Medical School, the first person to use TMS to make specific neurons fire. He built a small machine capable of generating magnetic field surges that excite neurons in a specific area. When Doidge wore this machine on his head, it made his fourth finger move by stimulating its region in his brain map. TMS can excite neurons to the point where they continue firing even after the machine is turned off, and this can produce therapeutic effects. For example, depression can be treated by triggering the underperforming prefrontal cortex.
Pascual-Leone also used TMS to analyze how people learn. He mapped the motor cortex brain area of blind subjects who were starting to learn braille, and measured their progress on Mondays and Fridays. These students learned from Monday to Friday for two hours, and Pascual-Leone found that, although their index finger-related brain maps changed as they learned to read faster, their progress on Mondays and Fridays differed. From the start, the students’ brain maps showed dramatic expansion on Fridays, likely due to their sustained efforts to learn during the week. However, by Monday, these maps returned to their normal size because there was no school on weekends. This pattern repeated for the first six months of learning. After six months, a change occurred: Friday maps did not increase as dramatically as before, while Monday maps began to grow, plateauing at 10 months. These new Monday maps correlated better with students’ average reading speed, and after a two-month break from school, the maps kept their expanded size. Pascual-Leone concludes there are two types of plasticity involved in learning: “Friday” changes are responsible for strengthening existing neuronal connections, while “Monday” changes are responsible for forging new neuronal connections. These results suggest sustained practice is essential to maintain and internalize a skill.
Pascual-Leone suspected the blind students read using their visual cortex, even though braille is conveyed through touch. When he used TMS to block their visual cortex, the students found they could no longer read braille. His research not only confirms the plasticity of the brain but made him curious about the mind’s effect on the ability to learn. Pascual-Leone asked two groups of amateurs to learn a sequence on the piano, but only one group was allowed to practice. The other group was told to sit in front of the piano and merely imagine playing the sequence. Both practiced for the same amount of time, and in the end, both were successful in learning the sequence and showed similar changes in their motor brain maps. From a neuroscientific standpoint, there is a small difference between imagining an action and performing it. There is also a pattern in neuron firing when people accomplish specific tasks, such as lifting a finger or pressing a button. This is how certain machines have been trained to read thoughts—such as devices that help people with paralysis move objects.
According to Pascual-Leone, the brain is like Play-Doh: It is constantly changing, and though it can learn to take on a specific shape, each iteration will never be the same as a previous version. The brain is plastic, not elastic. Patterns can still emerge from the plastic brain, but once a pattern is set, it paradoxically becomes harder to change. To unlearn bad habits or learn a new skill quickly, one must block the brain from using its competitor. For example, a school for blind children in Spain asks teachers to live blindfolded for a week to experience what their students feel daily. When Pascual-Leone mapped these teachers’ brains with TMS, he found their visual cortices processed other senses after two days.
Pascual-Leone theorizes areas of the brain such as the “visual” and “auditory” cortexes do not only process one sense. Rather, they are operators that decode abstract information about spatial relationships, movement, and shapes, which can be detected by any of the five senses. Thus, when people learn new skills by blocking the usual channels, they increase their brain’s processing power and its ability to use other senses. Doidge concludes by refuting philosopher René Descartes’s body-mind dualism: Pascual-Leone’s research proves even “immaterial” thoughts can leave material changes on the plastic brain.
Chapters 5-8 Analysis
Chapters 5-8 analyze how a better understanding of neuroplasticity can treat certain psychological and physical conditions, and how neuroplasticity itself can sometimes cause undesirable conditions—playing with the idea of Neuroplasticity and Rigidity. Chapters 5-6 introduce extreme cases that prove the plastic brain is malleable as long as it is given proper exercise. Chapter 5 is notable for using the work of neurologist Edward Taub to illustrate how stroke patients with paralysis can regain use of their limbs if they restrict their unaffected limbs. Taub’s discoveries in rehabilitation can be explained with a theory of competition, which Doidge calls the “use it or lose it” principle. This theory paints the brain as a system with limited resources. When a limb ceases working, the brain enters a period of shock and then begins assigning a different function to the area that has been freed of its previous task. Unless the patient actively forces the brain to relearn moving the limb after the initial shock, the plastic brain will prefer processing other easier tasks. However, because the brain is ultimately malleable, patients who have long been paralyzed, with time and effort, can teach their brains to process the weak signals coming from their paralyzed limbs. Over time, synaptic connections become stronger and the limbs can move again. Chapter 6 discusses this same theme of intentionally rewiring the brain, but in the context of a psychological condition (specifically, OCD).
Chapters 7-8 delve into how the plastic brain can also become the root cause of people’s woes. They point out the adaptable brain will continuously learn to operate more efficiently, and neurons that fire in tandem will see their connections strengthened, but this, in turn, means that once a routine has been established, it becomes both physiologically and psychologically difficult to break. Chapter 7 uses phantom pain to illustrate how some undesirable conditions can be “imagined.” Whenever the brain suddenly ceases receiving signals from a severed limb, it produces pain to alert the body of this danger. Thus, phantom pains are the result of “crossed wires” in the brain and therefore do not originate from the limb itself. However, Chapter 8 shows how imagination can instead treat otherwise untreatable psychological conditions (specifically, with devices like a mirror box). Overall, Chapters 5-8 explore how neuroplasticity can both cause and alleviate suffering.
