Most excited I’ve been while reading a book in a while. I emphatically suggest you read it and think on it for yourself.
The Brain that Changes itself – Stories of Personal Triumph from the Frontiers of Brain Science. By Norman Doidge, M.D.
1 – A Woman Perpetually Falling…
“We see with our brains, not with our eyes,” [Paul Bach-y-rita] says.
This claim runs counter to the commonsensical notion that we see with our eyes, hear with our ears, taste with our tongues, smell with our noses, and feel with our skin. Who would challenge such fats? But for Bach-y-Rita, our eyes merely sense changes in light energy; it is our brains that perceive and hence see.
How a sensation enters the brain is not important to Bach-Rita. “When a blind man uses a cane, he sweeps it back and forth, and has only one point, the tip, feeding him information through the skin receptors in the hand. Yet this sweeping allows him to sort out where the doorjamb is, or the chair, or distinguish a foot when he hits it, because it will give a little. Then he uses this information to guide himself to the chair to sit down. Though his hand sensors are where he gets the information and where the cane ‘interfaces’ with him, what he subjectively perceives is not the cane’s pressure on his hand but the layout of the room: chairs, walls, feet, the three-dimensional space. The actual receptor surface in the hand becomes merely a relay for information, a data port. The receptor surface loses its identify in the process.”
2 – Building Herself a Better Brain
The irony of this new discovery is that for hundreds of years educators did seem to sense that children’s brains had to be built up through exercises of increasing difficulty that strengthened brain functions. Up through the nineteenth and early twentieth centuries a classical education often included rote memorization of long poems in foreign languages, which strengthened the auditory memory (hence thinking in language) and an almost fanatical attention to handwriting, which probably helped strengthen motor capacities and thus not only helped handwriting but added speed and fluency to reading. Often a great deal of attention was paid to exact elocution and to perfecting the pronunciations of words. Then in the 1960s educators dropped such traditional exercises from the curriculum because they were too rigid, boring, and “not relevant.” But the loss of these drills has been costly; they may have been the only opportunity that many students had to systematically exercise the brain function that gives us fluency and grace with symbols. For the rest of us, their disappearance may have contributed to the general decline of eloquence, which requires memory and a level of auditory brainpower unfamiliar to us now. In the Lincoln-Douglas debates of 1858 the debaters would comfortably speak for an hour or more without notes, in extended memorized paragraphs; today many of the most learned among us, raised in our most elite schools since the 1960s, prefer the omnipresent PowerPoint presentation – the ultimate compensation for a weak premotor cortex.
Animals raised in enriched environments—surrounded by other animals, objects to explore, toys to roll, ladders to climb, and running wheels—learn better than genetically identical animals that have been reared in impoverished environments. Acetylcholine, a brain chemical essential for learning, is higher in rats trained on difficult spatial problems than in rats trained on simpler problems. Mental training or life in enriched environments increases brain weight by 5 percent in the cerebral cortex of animals and up to 9 percent in areas that the training directly stimulates. Trained or stimulated neurons develop 25 percent more branches and increase their size, the number of connections per neuron, and their blood supply. These changes can occur late in life, though they do not develop as rapidly in older animals as in younger ones. Similar effects of training and enrichment on brain anatomy have been seen in all types of animals tested to date.
3 – Redesigning the Brain
Fast ForWord is disguised as a children’s game. What is amazing about it is how quickly the change occurs. In some cases people who have had a lifetime of cognitive difficulties get better after only thirty to sixty hours of treatment. Unexpectedly, the program has also helped a number of autistic children.
[Michael] Merzenich claims that when learning occurs in a way consistent with the laws that govern brain plasticity , the mental “machinery” of the brain can be improved so that we learn and perceive with greater precision, speed, and retention.
Clearly when we learn, we increase what we know. But Merzenich’s claim is that we can also change the very structure of the brain itself and increase its capacity to learn. Unlike a computer, the brain is constantly adapting itself.
“The cerebral cortex,” he says of the thin outer layer of the brain, “is actually selectively refining its processing capacities to fit each task at hand.” It doesn’t simply learn; it is always “learning how to learn.”
The discovery of the critical period became one of the most famous in biology in the second half of the twentieth century. Scientists soon showed that other brain systems required environmental stimuli to develop. It also seemed that each natural system had a different critical period, or window of time, during which it was especially plastic and sensitive to the environment, and during which it had rapid, formative growth. Language development, for instance, has a critical period that begins in infancy and ends between eight years and puberty. After this critical period closes, a person’s ability to learn a second language without an accent is limited. In fact, second languages learned after the critical period are not processed in the same part of the brain as is the native tongue.
When it came to allocating brain-processing power, brain maps were governed by competition for precious resources and the principle of use it or lose it.
Merzenich and [Bill] Jenkins also showed that individual neurons got more selective with training. Each neuron in a brain map for the sense of touch has a “receptive field,” a segment on the skin’s surface that “reports” to it. As the monkey were trained to feel the disk, the receptive fields of individual neurons got smaller, firing only when small parts of the fingertip touched the disk. Thus, despite the fact that the size fo the brain map increased, each neuron in the map became responsible for a smaller part of the skin surface, allowing the animal to have finer touch discrimination. Overall, the map became more precise.
Merzenich and Jenkins also found that as neurons are trained and become more efficient, they can process faster. This means that the speed at which we think is itself plastic. Speed of thought is essential to our survival. Events often happen quickly, and if the brain is slow, it can miss important information. In one experiment Merzenich and Jenkins successfully trained monkeys to distinguish sounds in shorter and shorter spans of time. The trained neurons fired more quickly in response to the sounds, processed them in a shorter time, and needed less time to “rest” between firings. Faster neurons ultimately lead to faster thought—no minor matter—because speed fo thought is a crucial component of intelligence. IQ tests, like life, measure not only whether you can get the right answer, but how it takes you to get it.
They also discovered that as they trained an animal at a skill, not only did its neurons fire faster, but because they were faster their signals were clearer. Faster neurons were more likely to fire in synch with each other—becoming better team players—wiring together more and forming groups of neurons that gave off clearer and more powerful signals. This is a crucial point, because a powerful signal has greater impact on the brain. When we want to remember something we have heard we must hear it clearly, because a memory can be only as clear as its original signal.
Finally, Merzenich discovered that paying close attention is essential to long-term plastic change. In numerous experiments he found that lasting changes occurred only when his monkeys paid close attention. When the animals performed tasks automatically, without paying attention, they changed their brain maps, but they changes did not last. We often praise “the ability to multitask.” While you can learn when you divide your attention, doesn’t lead to abiding change in your brain maps.
In 1996 Merzenich, Paula Tallal, Bill Jenkins, and one of Tallal’s colleagues, psychologist Steve Miller, formed the nucleus of a company, Scientific Learning, that is wholly devoted to using neuroplastic research to help people rewire their brains.
One of the most important brain—activities one we don’t often think about—is the determination of how long things go on, or temporal processing. You can’t move properly, perceive properly, or predict properly if you can’t determine how long events last. Merzenich discovered that when you train people to distinguish very fast vibrations on their skin, lasting only 75 milliseconds, these same people could detect 75-millisecond sounds as well. It seemed that Fast ForWord was improving the brain’s general ability to keep time. Sometimes these improvements spilled over into visual processing as well.
When we perform an activity that requires specific neurons to fire together, they release [brain-derived neurotrophic factor] BDNF. This growth factor consolidates the connections bgetween those neurons and helps to wire them together so they fire together reliably in the future. BDNF also promotes the growth of the thin fatty coat around eveyr neuron that speeds up the trainsmission of the electrical signals.
During the critical period BDNF turns on the nucleus basalis, the part of our brain that allows us to focus our attention—and keeps it on, throughout the entire critical period. Once turned on, the nucleus basalis helps us not only pay attention bur remember what we are experiencing. It allows map differentiation and change to take place effortlessly. Merzenich told me, “It is like a teacher in the brain saying ‘Now this is really important—this you have to know for the exam of life.’” Merzenich calls the nucleus basalis and the attention system the “modulatory control system of plasticity”—the neurochemical system that, when turned on, puts the brain in an extremely plastic state.
The fourth and final service that BDNF performs—when it has completed strengthening key connections—is to help close down the critical period. Once the main neuronal connections are laid down, there is a need for stability and hence less plasticity in the system. When BDNF is released in sufficient quantities, it turns off the nucleus basalis and ends that magical epoch of effortless learning. Henceforth the nucleus can be activated only when something important, surprising, or novel occurs, or if we make the effort to pay close attention.
During the critical period,[Merzenich] argues, some situations overexcite the neurons in children how have genes that predispose them to autism, leading to the massive, premature release of BDNF. Instead of important connections being reinforced, all connections are. So much BDNF is released that it turns off the critical period prematurely, sealing all these connections in place, and the child is left with scores of undifferentiated brain maps and hence pervasive developmental disorders. Their brains are hyperexcitable and hypersensitive. If they hear one frequency, the whole auditory cortex starts firing. This si what seemed to be happening in Lauralee, who had to cover her bionic” ears when she heard music. Other autistic children are hypersensitive to touch and feel tormented when the labels in their clothes touch their skin. Merzenich’s theory also explains the high rates of epilepsy in autism: because of BDNF release, the brain maps are poorly differentiated, and because so many connections in the brain have been indiscriminately reinforced, once a few neurons start firing, the whole brain can be set off. It also explains why autistic children have bigger brains—the substance increases the fatty coating around the neurons.
If BDNF release was contributing to autism and language problems, Merzenich needed to understand what might cause young neurons to get “overexcited” and release massive amounts of the chemical.
Psychologically, middle age is often an appealing time because, all else being equal, it can be a relatively placid period compared with what has come before. Our bodies aren’t changing as they did in adolescence; we’re more likely to have a solid sense of who we are and be skilled at a career. We still regard ourselves as active, but we have a tendency to deceive ourselves into thinking that we are learning as we were before. We rarely engage in tasks in which we must focus our attention as closely as we did when we were younger, trying to learn a new vocabulary or master new skills. Such activities as reading the newspaper, practicing a profession of many years, and speaking our own language are mostly the replay of mastered skills, not learning. By the time we hit our seventies, we may not have systematically engage the systems in the brain that regulate plasticity for fifty years.
That’s why learning a new language in old age is so good for improving and maintaining the memory generally. Because it requires intense focus, studying a new language turns on the control system for plasticity and keeps it in good shape for laying down sharp memories of all kinds. No doubt Fast ForWord is responsible for so many general improvments in thinking, in part because it stimulates the control system for plasticity to keep up its production of acetylcholine and dopamine. Anything that requires highly focused attnetion will help that system—learning new physical activities that required concentration, solving challenging puzzles, or making a career change that requires that you master new skills and material. Merzenich himself is an advocate of learning a new language in old age. “You will gradually sharpen everything up again, and that will be very highly beneficial to you.”
4 – Acquiring Tastes and Loves
Given that sexuality is an instinct, and instinct is traditionally defined as a hereditary behavior unique to a species, varying little from one member to the next, the variety of our sexual tastes is curious. Instincts generally resist change and are thought to have a clear, non-negotiable, hardwired purpose, such as survival. Yet the human sexual “instinct” seems to have broken free of its core purpose, reproduction, and varies to a bewildering extent, as it does not in other animals, in which the sexual instinct seems to behave itself and act like an instinct.
No other instinct can so satisfy without accomplishing its biological purpose and no other instinct is so disconnected from its purpose. Anthropologists have shown that for a long time humanity did not know that sexual intercourse was required for reproduction. This “fact of life” had to be learned by our ancestors, just as children must learn it today. This detachment from its primary purpose is perhaps the ultimate sign of sexual plasticity.
When a person gets high on cocaine, becomes manic, or falls in love, he enters an enthusiastic state and is optimistic about everything, because all three conditions lower the firing threshold for the appetitive pleasure system, the dopamine-based system associated with the pleasure of anticipating something we desire. The addict, the manic, and the lover are increasingly filled with hopeful anticipation and are sensitive to anything that might give pleasure—flowers and fresh air inspire them, and a slight but thoughtful gesture makes them delight in all mankind. I call this process “globalization.” ♥
Globalization is intense when falling in love and is, I believe, one of the main reasons that romantic love is such a powerful catalyst for plastic change. Because the pleasure centers are firing so freely, the enamored person falls in love not only with the beloved but with the world and romanticizes his view of it. Because our brains are experiencing a surge of dopamine, which consolidates plastic change, any pleasurable experiences and associations we have in the initial state of love are thus wired into our brains.
Globalization not only allows us to take more pleasure in the world, it also makes it harder for us to experience pain and displeasure or aversion. Heath showed that when our pleasure centers fire, it is more difficult for the nearby pain and aversion centers to fire too. Things that normally bother us don’t. We love being in love not only because it makes it easy for us to be happy but also because it makes it harder for us to be unhappy.
Globalization also creates an opportunity for us to develop new tastes in what we find attractive, like the pockmark that gave Alberic such pleasure. Neurons that fire together wire together, and feeling pleasure in the presence of this normally unappealing pockmark causes it to get wired into the brain as a source of delight. A similar mechanism occurs when a “reformed” cocaine addict passes the seedy alleyway where he fist took the drug and is overwhelmed with cravings powerful enough that he goes back to it.
But the pains of love also have a chemistry. When separated for too long, lovers crash and experience withdrawal, crave their beloved, get anxious, doubt themselves, lose their energy, and feel run-down if not depressed. Like a little fix, a letter, an e-mail, or a telephone message from the beloved provides an instant shot of energy. Should they break up, they get depressed—the opposite of the manic high. These “addictive symptoms”—the highs, crashes, cravings, withdrawal, and fixes—are subjective signs of plastic changes occurring in the structure of our brains, as they adapt to the presence or absence of the beloved.
Walter J. Freeman, a professor of neuroscience at Berkeley, was the first to make the connection between love and massive unlearning. He has assembled a number of compelling biological facts that point toward the conclusion that massive neuronal reorganization occurs at two life stages: when we fall in love and when we begin parenting. Freeman argues that massive plastic brain reorganization—far more massive than in normal learning or unlearning—becomes possible because of a brain neuromodulator.
Neuromodulators are different from neurotransmitters. While neurotransmitters are released in the synapses to excite or inhibit neurons, neuromodulators enhance or diminish the overall effectiveness of the synaptic connections and bring about enduring change. Freeman believes that when we commit in love, the brain neuromodulator oxytocin is released, allowing existing neuronal connections to melt away so that changes on a large scale can follow.
Oxytocin is sometimes called the commitment neuromodulator because it reinforces bonding in mammals. It is released when lovers connect and make love—in humans oxytocin is released in both sexes during orgasm—and when couples parent and nurture their children. In women oxytocin is released during labor and breastfeeding.
Whereas dopamine induces excitement, puts us into high gear, and triggers sexual arousal, oxytocin induces a calm, warm mood that increases tender feelings and attachment and may lead us to lower our guard. A recent study shows that oxytocin also triggers trust. When people sniff oxytocin and then participate in a financial game, they are more prone to trust others with their money. Though there is still more work to be done on oxytocin in humans, evidence suggests that its effect is similar to that in prairie voles: it makes us commit to our partners and devotes us to our children.
Oxytocin is not, however, released with the first litter—only with those litters that follow—suggesting that the oxytocin plays the role of wiping out the neural circuits that bonded the mother with her first litter, so she can bond with her second. … Freeman proposes that oxytocin melts down existing neuronal connections that underlie existing attachments, so new attachments can be formed. Oxytocin, in this theory, does not teach parents to parent. Nor does it make lovers cooperative and kind; rather, it makes it possible for them to learn new patterns.
Robert Stoller, M.D., a California psychoanalyst, did make important discoveries through visits to S&M and B&D (bondage and discipline) establishments in Los Angeles. He interviewed people who practiced hardcore sadomasochism, which inflicts real pain on the flesh, and discovered that masochistic participants had all had serious physical illnesses as children and had undergone regular, terrifying, painful medical treatment. “As a result,” writes Stoller, “they had to be confined severely and for long periods [in hospitals] without the chance to unload their frustration, despair and rage openly and appropriately. Hence the perversions.” As children, they consciously took their pain, their inexpressible rage, and reworked it in daydreams, in altered mental states, or in masturbation fantasies, so they could replay the story of the trauma with a happy ending and say to themselves, This time, I win. And the way they won was by erotizing their agony.
The idea that an “inherently” painful feeling can become pleasurable may at first strike us as hard to believe, because we tend to assume that each of our sensations and emotions is inherently either pleasurable (joy, triumph, and sexual pleasure) or painful (sadness, fear, and grief). But in fact this assumption does not hold up. We can cry tears of happiness and have bittersweet triumphs; and in neuroses people may feel guilty about sexual pleasure, or no pleasure at all, where others would feel delight. An emotion that we think inherently unpleasureable, such as sadness, can, if beautifully and subtly articulated in music, literature, or art, feel not only poignant but sublime.
5 – Midnight Resurrections
6 – Brain Lock Unlocked
[Jeffrey M.] Schwarz divides the therapy into a number of steps, of which two are key.
The first step is for a person having an OCD attach to relabel what is happening to him, so that he realizes that what he is experiencing is not an attack of germs, AIDS, or battery acid but an episode of OCD. He should remember that brain lock occurs in the three parts of the brain. As a therapist I encourage OCD patients to make the following summary for themselves: “Yes, I do have a real problem right now. But it is not germs, it is my OCD.” This relabeling allows them to get some distance from the content of the obsession and view it in somewhat the same way Buddhists view suffering in meditation: they observe its effects on them and so slightly separate themselves from it.
7 – Pain
…[Vilayanur Subramanian] Ramachandran developed his next idea: that pain is a complex system under the plastic brain’s control. He summed this up as follows: “Pain is an opinion on the organism’s state of health rather than a mere reflexive response to injury.” The brain gathers evidence from many sources before triggering pain. He has also said that “pain is an illusion” and that “our mind is a virtual reality machine,” which experiences the world indirectly and processes it at one remove, constructing a model in our head. So pain, like the body image, is a construct of our brain. Since Ramachandran could use his mirror box to modify a body image and eliminate a phantom and its pain, could he also use the mirror box to make chronic pain in a real limb disappear?
8 – Imagination
When [Alvaro] Pascual-Leone used [transcranial magnetic stimulation] TMS to map the motor cortex, he found that the maps for people’s “Braille reading fingers” were larger than the maps for their other index fingers and also those for the index fingers of non-Braille readers. Pascual-Leone also found that the motor maps increased in size as the subjects increased the number of words per minute they could read. But his most surprising discover, one with major implications for learning any skill, was the way the plastic change occurred over the course of each week.
The subjects were mapped with TMS on Fridays (t the end of the week’s training), and on Mondays (after they had rested for the weekend). Pascual-Leone found that the changes were different on Friday and Monday. From the beginning of the study, Friday maps showed very rapid and dramatic expansion, but by Monday these maps had returned to their baseline size. The Friday maps continued to grow for six months—stubbornly returning to baseline each Monday. After about six months the Friday maps were still increasing but not as much as in the first six months.
Monday maps showed an opposite pattern. They didn’t begin to change until six months into the training; then they increased slowly and plateaued at ten months. The speed at which the subjects could read Braille correlated much better with the Monday maps, and though the changes on Mondays were never as dramatic as on Fridays, they were more stable. At the end of ten months the Braille students took two months off. When they returned, they were remapped, and their maps were unchanged from the last Monday mapping two months before. Thus daily training led to dramatic short-term changes during the week. Thus daily training led to dramatic short-term changes during the week. But over the weekends, and months, more permanent changes were seen on Mondays.
Pascual-Leone believes that the differing results on Monday and Friday suggest differing plastic mechanisms. The fast Friday changes strengthen existing neuronal connections and unmask buried pathways. The slower, more permanent Monday changes suggest the formation of brand-new structures, probably the sprouting of new neuronal connections and synapses.
Understanding this tortoise-and-hare effect can help us understand what we must do to truly master new skills. After a brief period of practice, as when we cram for a test, it is relatively easy to improve because we are likely strengthening existing synaptic connections. But we quickly forget what we’ve crammed—because these are easy-come, easy-go neuronal connections and are rapidly reversed. Maintaining improvement and making a skill permanent require the slow steady work that probably forms new connections. If a learner thinks he is making no cumulative progress, or feels his mind is “like a sieve,” he needs to keep at the skill until he gets “the Monday effect,” which in Braille readers took six month. The Friday-Monday difference is probably why some people, the “tortoises,” who seem slow to pick up a skill, may nevertheless learn it better than their “hare” friends—the “quick studies” who won’t necessarily hold on to what they have learned without the sustained practice that solidifies the learning.
Consider the case of Rüdiger Gamm, a young German man of normal intelligence who turned himself into a mathematical phenomenon, a human calculator. Though Gamm was not born with exceptional mathematical ability, he can now calculate the ninth power or the fifth root of numbers and solve such problems as “What is 68 times 76?” in five seconds. Beginning at age twenty, Gamm, who worked in a bank, began doing four hours of computational practice a day. By the time he was twenty-six, he had become a calculating genius, able to make his living by performing on television. Investigators who examined him with a positron emission tomography (PET) brain scan while he was calculating found he was able to recruit five more brain areas for calculating than “normal” people. The psychologist Anders Ericsson, an expert in the development of expertise, has shown that people like Gamm rely on long-term memory to help them solve mathematical problems when others rely on short-term memory. Experts don’t store the answers, but they do store key facts and strategies that help them get answers, but they do store key facts and strategies that help them get answers, and they have immediate access to them, as though they were in short-term memory. This use of long-term memory for problem solving is typical of experts in most fields, and Ericsson found that becoming an expert in most fields usually takes about a decade of concentrated effort.
One reason we can change our brains simply by imagining is that, from a neuroscientific point of view, imagining an act and doing it are not as different as they sound. When people close their eyes and visualize a simple object, such as the letter a, the primary visual cortex lights up, just as it would if the subjects were actually looking at the letter a. Brain scans show that in action and imagination many of the same parts of the brain are activated. That is why visualizing can improve performance.
In an experiment that is as hard to believe as it is simple, Drs. Guang Yue and Kelly Cole showed that imagining one is using one’s muscles actually strengthens them. The study looked at two groups, one that did physical exercise and one that imagined doing exercise. Both groups exercised a finger muscle, Monday through Friday, for four weeks. The physical group did trials of fifteen maximal contractions, with a twenty-second rest between each. The mental group merely imagined doing fifteen maximal contractions, with a twenty-second rest between each, while also imagining a voice shouting at them, “Harder! Harder! Harder!”
At the end of the study the subjects who had done physical exercise increased their muscular strength by 30 percent, as one might expect. Those who only imagined doing the exercise, for the same period, increased their muscle strength by 22 percent. The explanation lies in the motor neurons of the brain that “program” movements. During these imaginary contractions, the neurons responsible for stringing together sequences of instructions for movements are activated and strengthened, resulting in increased strength when the muscles are contracted.
…consider this: in some cases, the faster you can imagine something, the faster you can do it. Jean Decety of Lyon, France, has done different versions of a simple experiment. When you time how long it takes to imagine writing your name with your “good hand,” and then actually write it, the times will be similar. When you imagine writing your name with your nondominant hand, it will take longer both to imagine it and to write it. Most people who are right-handed find that their “mental left hand” is slower than their “mental right hand.”
Pascual-Leone explains…with a metaphor. The plastic brain is like a snowy hill in winter. Aspects of that hill—the slope, the rocks, the consistency of the snow—are, like our genes, a given. When we slide down on a sled, we can steer it and will end up at the bottom of the hill by following a path determined both by how we steer and the characteristics of the hill. Where exactly we will end up is hard to predict because there are so many factors in play.
“But,” Pascual-Leone says, “what will definitely happen the second time you take the slope down is that you will more likely than not find yourself somewhere or another that is related to the path you took the first time. It won’t be exactly that path, but it will be closer to that one than any other. And if you spend your entire afternoon sledding down, walking up, sledding down, at the end you will have some paths that have been used a lot, some that have been used very little…and there will be tracks that you have created and it is very difficult now to get out of those tracks. And those tracks are not genetically determined anymore.”
The mental “tracks” that get laid down can lead to habits, good or bad. If we develop poor posture, it becomes hard to correct. If we develop good habits, they too become slidified.
He blindfolded people for five days, then mapped their brains with TMS. He found that when he blocked out all light—the road “block” had to be impermeable—the subjects’ “visual” cortices began to process the sense of touch coming from their hands, like blind patients learning Braille. What was most astounding, however, was that the brain reorganized itself in just a few days. With brain scans Pascual-Leone showed that it could take as few as two days for the “visual” cortex to begin processing tactile and auditory signals. (As well, many of the blindfolded subjects reported that as they moved, or were touched, or heard sounds,t hey began having visual hallucinations of beautiful, complex scenes of cities, skies, sunsets, Lilliputian figures, cartoon figures). Absolute darkness was essential to the change because vision is so powerful a sense that if any light got in, the visual cortex preferred to process it over sound and touch.
Everything your “immaterial” mind imagines leaves material traces. Each thought alters the physical state of your brain synapses at a microscopic level. Each time you imagine moving your fingers across the keys to play the piano, you alter the tendrils in your living brain.
The experiments are not only delightful and intriguing, they also overturn the centuries of confusion that have grown out of the work of the French philosopher René Descartes…
9 – Turning our Ghosts into Ancestors
Most people assume that our genes shape us—our behavior and our brain anatomy. [Eric] Kandel‘s work shows that when we learn our minds also affect which genes in our neurons are transcribed. Thus we can shape our genes, which in turn shape our brain’s microscopic anatomy.
Kandel argues that when psychotherapy changes people, “it presumably does so through learning, by producing changes in gene expression that alter the strength of synaptic connections, and structural changes that alter the anatomical pattern of interconnctions between nerve cells of the brain.” Psychotherapy works by going deep into the brain and its neurons and changing their structure by turning on the right genes. Psychiatrist Dr. Susan Vaughan has argued that the talking cure works by “talking to neurons,” and that an effective psychotherapist or psychoanalyst is a “microsurgeon of the mind” who helps patients make needed alterations in neuronal networks.
Frued state that when two neurons fire simultaneously, this firing facilitates their ongoing association.
The well-developed memory system in twenty-six-month-old children is called “procedural” or “implicit” memory. These terms are often used interchangeably by Kandel. Procedural/implicit memory functions when we learn a procedure or group of automatic actions, occurring outside our focused attention, in which words are generally not required. Our nonverbal interactions with people and many of our emotional memories are part of our procedural memory system. As Kandel says, “During the first 2-3 years of life, when an infant’s interaction with its mother is particularly important, the infant relies primarily on its procedural memory systems.” Procedural memories are generally unconscious. Riding a bike depends on procedural memory, and most people who ride easily would have trouble consciously explaining precisely how they do it. The procedural memory system confirms that we can have unconscious memories, as Freud proposed.
REM sleep has also been shown to be particularly important for enhancing our ability to retain emotional memories and for allowing the hippocampus to turn short-term memories of the day before into long-term ones (i.e., it helps make memories more permanent, leading to structural change in the brain).
Depression, high stress, and childhood trauma all release glucocorticoids and kill cells in the hippocampus, leading to memory loss. The longer people are depressed, the smaller their hippocampus gets. The hippocampus of depressed adults who suffered prepubertal childhood trauma is 18 percent smaller than that of depressed adults without childhood trauma—a downside of the palstic brain: we literally lose essential cortical real estate in response to illness.
If the stress is brief, this decrease in size is temporary. If it is too prolonged, the damage is permanent. As people recover from depression, their memories return, and research suggest their hippocampi can brow back. In fact, the hippocampus is one of the two areas where new neurons are created from our own stem cells as part of normal functioning.
The plastic paradox is that the same neuroplastic properties that allow us to change our brains and produce more flexible behaviors can also allow us to produce more rigid ones. All people start out with plastic potential. Some of us develop into increasingly flexible children and stay that way through our adult lives. For others of us, the spontaneity, creativity, and unpredictability of childhood gives way to a routinized existence that repeats the same behavior and turns us into rigid caricatures of ourselves. Anything that involves unvaried repetition—our careers, cultural activities, skills, and neuroses—can lead to rigidity. Indeed, it is because we have a neuroplastic brain that we can develop these rigid behaviors in the first place. As Pascual-Leone’s metaphor illustrates, neuroplasticity is like pliable snow on a hill. When we go down the hill on a sled, we can be flexible because we have the option of taking different paths through the snoft snow each time. But should we choose the same path a second or third time, tracks will start to develop, and soon we will tend to get stuck in a rut—our route will now be quite rigid, as neural circuits, once established, tend to become self-sustaining. Because our neuroplasticity can give rise to both mental flexibility and mental rigidity, we tend to underestimate our own potential for flexibility, which most of us experience only in flashes.
10 – Rejuvenation
[Gage’s] theory, that novel environments may trigger neurogenesis, is consistent with Merzenich’s discovery that in order to keep the brain fit, we must learn something new, rather than simply replaying already-mastered skills.
We now know that exercise and mental activity in animals generate and sustain more brain cells, and we have many studies confirming that humans who lead mentally active lives have better brain function. The more education we have, the more socially and physically active we are, and the more we participate in mentally stimulating activities, the less likely we are to get Alzheimer’s disease or dementia.
Not all activities are equal in this regard. Those that involve genuine concentration—studying a musical instrument, playing board games, reading, and dancing—are associated with a lower risk for dementia. Dancing, which requires learning new moves, is both physically and mentally challenging and requires much concentration. Less intense activities, such as bowling, babysitting, and golfing, are not associated with a reduced incidence of Alzheimer’s.
11 – More than the Sum of her Parts
From his research Grafman has identified four kinds of plasticity.
The first is “map expansion,” described above, which occurs largely at the boundaries between brain areas as a result of daily activity.
The second is “sensory reassignment,” which occurs when one sense is blocked, as in the blind. When the visual cortex is deprived of its normal inputs, it can receive new inputs from another sense, such as touch.
The third is “compensatory masquerade,” which takes advantage of the fact that there’s more than one way fo ryour brain to approach a task. Some people use visual landmarks to get from place to place. Others with “a good sense of direction” have a strong spatial sense, so if they lose their spatial sense in a brain injury, they can fall back on landmarks. Until neuroplasticity was recognized, compensatory masquerade—also called compensation or “alternative strategies,” such as switching people with reading problems to audio tapes—was the chief method used to help children with learning disabilities.
The fourth kind of plasticity is “mirror region takeover.” When part of one hemisphere fails, the mirror region in the opposite hemisphere adapts, taking over its mental function as best it can.
Appendix 1 – the Culturally Modified Brain
So a neuroplastically informed view of culture and the brain implies a two-way street: the brain and genetics produce culture, but culture also shapes the brain. Sometimes these changes can be dramatic.
…Easterners [i.e. Asia] perceive holistically, viewing objects as they are related to each other or in a context, whereas Westerners [N. America and Europe] perceive them in isolation. Easterners see through a wide-angle lens. Westerners use a narrow one with a sharper focus. Everything we know about plasticity suggests that these different ways of perceiving, repeated hundreds of times a day, in massed practice, must lead to changes in neural networks responsible for sending and perceiving.
Television watching, one of the signature activities of our culture, correlates with brain problems. A recent study of more than twenty-six hundred toddlers shows that early exposure to television between the ages of one and three correlates with problems paying attention and controlling impulses later in childhood. For every hour of TV the toddlers watched each day, their chances of developing serious attentional difficulties at age seven increased by 10 percent.
Appendix 2 – Plasticity and the Idea of Progress