What Recent Brain Research Tells Us about Learning

Editor's Note: This is the first in a series of three articles on recent brain research and its applications to teaching and learning. The next installments will focus on language acquisition, memory, how the brain processes learning, and, as author Kenneth Wesson describes it, Where Is God in the Brain? A companion piece for this series, containing a detailed description of the parts of the brain and their functions, will be available on our website, Memory and the Brain.

Talking about what motivates scientists, neuroscientist Michael Gazzaniga says, "The stuff that drives scientists into their laboratories instead of onto the golf links is the passion to answer questions, hopefully important questions, about the nature of nature. Getting a fix on important questions and how to think about them from an experimental point of view is what scientists talk about, sometimes endlessly."

As educators and parents become more cognizant of the impact they have on the brain of a developing child, they often begin asking questions like, "How does the human brain work and what can I do that will nurture the covert processes by which it operates?" This intriguing, centuries-old question is still an enormous mystery to most of us. However, there are several compelling sub-questions whose individual answers can aid us in piecing together some of the constituent keys to constructing an answer to our important original question. Among those questions are: What parts of the brain are involved in thinking, learning, and memory? Does the brain change during life and during the process of learning, or is it a permanently fixed/hard-wired creation? What can we do in our schools (and homes) to enhance learning?

In years past, educators, psychologists, and philosophers would talk about learning, knowledge acquisition, and child development often without ever mentioning the brain. However, the most recent advances in the fields of molecular biology, neuroanatomy, medicine, brain-imaging, genetics, and the numerous branches of the cognitive neurosciences that are emerging today permit us to take a closer look at the chemical, functional, and structural aspects of just how the brain actually does work. We are discovering many of the neurophysiological correlates of cognitive functioning and the neural events that regulate all of the components that go into the makings of human learning. The human brain, acclaimed as the universe's most complex structure, is gaining currency in these discussions and is ascending to its rightful place as the focal point of all equations for learning.

It has been said that the next great journey of discovery for humankind will not be in outer space, but in the "inner space" of the human brain. In order to grasp what is happening in that inner space of our students and children (to say nothing of our own brains), it is helpful to understand what neuroscientists have learned in recent years.

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What should you know about brain cells?

The two most prevalent types of nerve cells in the brain are glial cells and neurons. Glial cells comfortably outnumber neurons ten to one, although some neuroscientists estimate the figure to be as high as fifty to one. Higher ratios of glial cells to neurons appear to correlate with greater degrees of cerebral functioning in human brains. Albert Einstein, who had 40 percent more glial cells than men of a comparable age, is frequently used as one example of that relationship. Somewhere between seventy and ninety percent of the cells in the cerebral cortex are glial cells, whose main responsibility is to play "nursemaid" to the neurons by assisting, pampering, and nourishing the exceptionally talkative neurons. Without glia, neurons could not carry out their operations properly and all neural communications would be halted.

Early psychologists surmised that glial (meaning "glue") cells helped neurons remain in their proper places in the cerebral cortex. Unlike most neurons, glial cells actually reproduce inside the brain. Most brain tumors are gliomas, since glial cells are mitotic, not neuromas. Because the majority neurons are considered postmitotic, they are largely unable to re-enter cell division cycles, and do not divide for the most part. The neurons that you are born with must be carefully nourished and guarded to last your entire life -- over eighty years for most Americans. Very few new neurons seem to be generated later.

The human brain is composed of more than one trillion nerve cells in total, and roughly 100 billion of them are neurons. So small in size are the brain's neurons that if they were lined up single file, just one cubic centimeter of them would stretch over 400,000 miles. Neurons are the fundamental building blocks in the cerebral cortex and serve as the brain's primary "network communicators." For decades, it was believed that only the neurons communicated with one another. However, recent research has discovered that some glial cells may also contribute to cortical communications. Neurons operate (1) the sensory systems necessary for data intake, (2) the decision-making systems in the frontal lobes dedicated to informational processing, and (3) the motor systems that carry out our decisions by executing the actions we take or the movements we make.

There are three basic parts of each neuron -- the main cell body, the dendrites, and the axon. Dendrites are the antenna-like extensions emanating from the neuron that receive communication signals from other neurons. They can make as many as 50,000 connections with other neurons in their effort to decipher and encode the outside world. Dendrites increase with use and from a stimulating environment. Conversely, they will shrink from neglect or impoverishment, whether that poverty comes from a lack of stimulation, poor nutrition, excessive levels of fear in the environment, or a host of other negative sources.

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To maintain neuronal functioning, one of the chief assignments of glial cells is to produce myelin, a fatty insulating substance comparable to the rubberized insulation found surrounding an electrical cord on a home appliance. Neurons communicate by sending electro-chemical signals to one another. The myelination on the axons facilitates the sending of the electrical component of a signal more efficiently. With the protective coating surrounding the signal-sending elongated portion of the neuron, electrical signals can travel more rapidly down the axon without the signal scattering and inadvertently activating nearby brain cells. The devastating effects of diseases like multiple sclerosis are the result of de-myelination taking place on the axons of nerve cells found in both the brain and the spinal column.

When some students experience various problems in reading, those difficulties are possibly located in the frontal lobe of the brain in the region that encompasses Broca's Area. Most important in the cases of some poor readers is the fact that this area is frequently quite low in myelin formations. The abnormalities are in this frontal tract and not in the visual cortex as once thought.

The neurons linked to the critical brain circuits that handle survival skills are the first candidates for myelination inside the womb. Otherwise, we might not survive our critical first year of life. Further myelination continues on a gradual basis in the brain, where completely different regions of the brain are myelinated according to genetic instructions directing all developmental activities at their designated times. A careful analysis of the precise order in which various areas of the brain are myelinated also provides us with information regarding when a child is ready for learning and/or mastering different kinds of concepts, ideas, or assignments. There is an interesting correlation between the synchronous development of particular competencies and the simultaneous myelination of the brain areas localized for carrying out a specific responsibility in the brain.

Dr. Sally Shaywitz at Yale University is currently tracking the cortical changes in the brains of five- and six-year-old novice readers before they learn how to read as compared to afterwards. These brain alterations are being compared to the expected structural and functional changes that occur in early cortical development of children of similar ages, as well as comparisons with the brains of experienced readers.

The brain processes an average of approximately 40,000 bits of neuro-data per second. Each of these elements gets dissected and key aspects of an experience are broken down based on the specific traits, characteristics, and parts composing it. All informational contacts inside the brain occur through the transmission of neurons, where each neuron pitches in a single ingredient that goes into the making of any given experience or single idea. Each of the deconstructed "pieces" is forwarded to the region of the brain that has specialized neurons that process a single element of a specific nature.

When an individual watches a yellow ball roll across a table, the color yellow goes to one part of his or her brain, while the shape of the ball goes to another. The movement is processed elsewhere and the association cortex links the object "table" with the event, while line orientation is sent to still another area of the cerebral cortex, and so forth, each element receiving a completely different type of analysis and processing. This data dissection and storage method allows the brain to process a limitless number of experiences using cells linked to many similar network systems.

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When information arrives in the cerebral cortex for analysis, the brain attempts to match each component with previously stored memory elements residing on an existing neural network with similar traits. If a match is made, the constituent elements and the larger event will be "recognized." If not, the search continues, although we are often unaware of the ongoing subconscious brain processing. This is why many "ah-hah" experiences occur at 3:00 a.m.

As the various factors that make up a memory are encoded by the cerebral cortex and the specialized sub-cortical structures that become involved in the process, a particular circuit of neurons is activated. The explicit elements of any memory are actually a collection of those representative neurons that are distributed throughout a number of different regions in the brain, but they operate synchronously to re-assemble a distinct memory by "re-collecting" its pieces. When the specialized neurons representing the pieces of that same memory begin to fire together, they will all fire together eventually (whether they do so accurately, prematurely, or even erroneously). Repeating an activity among the same combination of neurons strengthens their connections. Neurons that actively fire together (a signal travels at approximately 270 miles per hour) retain strong synaptic connections. As the saying goes, "Neurons that fire together, wire together." Each time you think and re-think about an event, that memory is fortified in the brain, which is why obsessions, compulsions, and states of "depression" can be so inescapable or debilitating. It is the "wiring" of neurons that cements behaviors and memories together along with the facts or details related to a given event.

Memories and skills can erode. When the representative cells composing a memory are damaged or destroyed, their branch-like connections (the dendrites) often retract and the remaining neurons will need to "re-wire" themselves around the damaged area. This process is how physical therapy and re-training operate, by neurologically re-establishing connections for those memories and important physical functions that are critical to one's physical, emotional, or psychological survival.

Similar to the recently discovered "mirror neurons" (nerve cells that are activated when the brain anticipates an explicitly clear overt action by someone else), there are sensory-specific regions of the cortex that are re-activated when a particular object or sound is recalled. Using brain-imaging techniques such as Positron Emission Tomography (PET) scans, which monitor cerebral blood flow, or a functional MRI in which moment-by-moment cerebral activity is detected, neurologists have shown that specific areas of the auditory or visual cortex were reactivated based on precise and specific memories. Interestingly, the areas were in exactly the same locations that were active when the initial exposure to the object was experienced, proving that memories are truly "reconstructions" created by the exact same neural array.

When the brain processes incoming information, it is generally moved from the posterior (back) area of the brain forward to the anterior areas of the brain (immediately behind the forehead) as increasingly more sophisticated analysis of data takes place. Since 4/5 of the information entering the brain is first routed through the eyes, information is transmitted forward from the visual cortex ("I saw something") to the association cortex ("What was that? Have we recorded anything like it previously?") The association cortices send the information to the appropriate regions of the cortex for further processing. Once the incoming data has been analyzed by the pertinent processing systems, a "thoughtful/ rational" decision is made by the frontal cortex, prompting the most "reasonable" response based on how that information was assessed and the conclusions drawn. The final commands are sent to the motor cortex ("What should I do?"), which executes the directives sent by the decision-making frontal cortex.

One important goal of the growing young brain is to learn how effectively to attend to relevant environmental information (to "essentialize" as psychologist, Robert Grant describes the neural procedure) and to simultaneously discard all unimportant data -- distinguishing the relevant from the superfluous. When new stimuli are connected to a prior experience, particularly one that has a very strong emotional connection, the information is suddenly elevated to a priority position for preferred processing. In psychology, this is known as "motivation"; in life, it is sometimes called desperation. Daniel Goldman refers to the event as an "emotional hijacking" of the cerebral cortex.

However, it is well-known that all individuals do not process the same stimuli in exactly the same way. Testimony to this fact is seen daily in the courtroom as well as the classroom. When students submit their written materials to a teacher, their work serves as hard evidence that information processed by several different brains will frequently be recalled in completely different ways, all unrelated to one another (including the original author, the teacher). Human beings all process information based on the idiosyncratic ways in which our 100 billion neurons have been uniquely networked. Research has revealed that an individual's brain configurations are not only personally "tailor-made," but in many ways, are even more unique than our fingerprints. Thus, all of our perceptions are meticulously filtered through our well-entrenched biases. Those biases come complete with their own neuronal representations and person-specific internal wiring. Each individualized brain has been molded into a distinctly unique organ.

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In addition to human beings seeing and recalling events in immensely different ways (as evidenced by the varying reconstructions of the same events when we ask students, spouses, witnesses in court to describe "what happened"), various living organisms also analyze the same input in completely divergent ways. Insects process infrared rays as light, while the human neurobiological system will process this same stimuli as heat. Dogs will detect, dissect, and act upon sounds to which their human owners are completely oblivious. The dog's owner is not uncaring or negligent; people simply were not bestowed with the neural mechanisms necessary to decipher particular sounds at the pitch levels that the brains of dogs and other organisms find unavoidably "natural" to them.

If a brain is capable of processing the elements of an event, idea, object, or incident, then the faculty itself is evident that a corresponding set of neurons has made it all possible. The series of events that allowed for the transmission, analysis, and interpretation of the information inside the brain came by way of a specific type of neuronal processing.

For centuries, scientists and children have watched with amazement as spiders ensnared what appeared to humans to be pathetically errant insects, whose last grave mistake was to accidentally fly into a spider's cobweb. Human beings viewed the web as being nearly transparent, which, to humans at least, accounted for the poor bug's "flight plan error" resulting in its fatal capture. However, the ways in which we process this event are distinctly different from the manner in which either the spider or the insect "sees" things.

First, a spider is exclusively interested in attracting only specific insects (ants, wasps, bees, and fellow spiders are not the chosen victims). Second, insects do not fail to see the web at all. In fact, they see the spider's cobweb quite vividly. Insects are captured because they in fact do observe the web directly in front of them, but in a treacherous way that the crafty spider had intended. It was recently discovered that, in ultraviolet light, a spider's web consists of visual patterns, as seen by the insects, that mimic particular flowers. Those images are of just the species of flowers that a specific kind of insect searches for when buzzing around our planet. The insect gets trapped because its nerve cells process the spider's web, not as the menacing mesh net that humans clearly see, but as the kind of flowers for which the insect regularly seeks.

The insect does not know that its preferences are the kinds of which the spider is clandestinely well aware. The spider's handiwork, as it turns out, is a net-like artifact that impersonates a low budget, deceptive art piece. It is a life-sized mural of flowers, but only to an insect, which, of course, is all that matters to his nemesis, the spider. We have been baffled by this spider-insect conundrum for eons, primarily due to a complete neuronal disconnect between the human and insect neuronal processing systems.

Similarly, neurons in a frog's brain fire incessantly when a horizontal matchstick is placed directly in front of him mimicking a worm. However, if the same matchstick is presented to the frog in a vertical position, the frog's visual system does not fire or respond at all. The upright stick simply does not register.

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There is a comparable state of affairs found in the brains of insect-eating monkeys, leaf-eating primates, and their fruit-eating cousins. In each group, only the food of choice stimulates an individual's brain circuitry, when that particular kind of food is observed and is categorized as "food." Those foods preferred by primates with a different palate do not register on the retina of other primates. For example, inside an insect-eating monkey's brain, the neural networks would not resonate with fresh fruits nor consider a ripe plum as something that would fall into the category of "food."

What does this mean for educators? Essentially, that any incoming data that does not match a particular human brain's prior experiences simply does not register in the brain (neurons do not respond in any recognizable or meaningful way). Background knowledge is critical for any new or meaningful student learning. This is also the reason why a foreign language might sound like incomprehensible chatter to one individual, while another finds it to be the best and only fitting way of communicating with other people.

What is this talk lately about "mirror neurons"?

While watching a televised boxing match, football game, or mystery, have you ever noticed yourself perspiring? When a parent sticks his tongue out at a newborn baby, the infant will often reciprocate. When I yawn, you will likely yawn without thought, hesitation, or control. While watching a movie or reading a novel, you might find yourself crying. While witnessing someone else's vaccination, you cringe and sometimes scream, "Ouch!" What brain mechanisms cause such behaviors?

A series of "monkey see, monkey do" neurons with absolutely fascinating properties was recently discovered in the cerebral cortex of monkeys. Giaccamo Rizzollati, of the University of Parma, Italy, found a system of brain cells, now known as "mirror cells," in the ventral premotor area of the frontal lobes of the brain. This area is a part of the larger premotor cortex, whose activities are linked to planning and initiating movements. Immediately anterior to the motor area is a cortical strip of the brain referred to as the Supplementary Motor Area (SMA) or the premotor cortex. The premotor cortex is a functional brain landmark separating the motor input (sensory/detecting) and output (motor/performing) systems. All proposed actions are rehearsed here before being executed by the motor system.

This cluster of neurons fires a signal when a monkey physically performs a single highly specific action with its hand. Whether pushing, pulling, tugging, or grasping an object, or when picking up or putting a peanut in its mouth, a particular series of neurons in the motor cortex is very active. However, the fascinating characteristic about mirror neurons is that many of the same neurons in the premotor areas also fired when the monkey watched another monkey or the experimenter perform the exact same task! During these experiments, it became easy to predict precisely which neurons would fire based on which activity the monkey was observing. Interestingly, when mechanical tools performed the same task, the mirror neurons remained inactive. However, they fired rapidly when a monkey watched a living being in action.

TAnytime a student watches a teacher or when he or she watches another student while working in a cooperative learning setting, mirror neurons are likely working in a similarly sophisticated observation-execution matching system. When we watch another human being perform a task or even starting to perform that action, there is a high probability that mirror neurons are beginning to fire at an incredible rate. Thus, mirror neurons faithfully help "read" the intentions of others, and they play a critically important, behind-the-scenes role in empathy, imitation learning, deciphering facial cues, early language development, social skills, and cultural rules. The ability to predict, mimic, and understand the actions of others is vital to social and physical survival. During verbal discourse, even anticipating another person's words as they complete a sentence seems to be associated with these newly discovered neurons.

Education and parenting are among some of the human endeavors most reliant on the proper functioning of mirror neurons. Isn't the goal of teaching and parenting to get exactly the same neuronal systems firing in our students and children that are actively at work within the adult's neural networks? Mentoring programs and the master-apprentice relationship used in contemporary educational settings are based on the successful transfer of skills governed by active imitation. Mirror cells foster high learning levels, promote acceptable social behaviors, and help in the important skill of understanding one another's intentions, be they malicious or generous.

There is fairly clear and convincing evidence of what can occur when mirror neurons go awry. Without properly functioning mirror neurons, a child may not understand or empathize with other people and, therefore, he or she will completely withdraw emotionally and socially. These are the cardinal traits of the autistic child. Antisocial, amoral serial killers also reveal sub-normal levels of activity in the frontal lobes and in the premotor region of the brain.

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Equally fascinating are the cases in which a patient, who experiences a right hemispheric stroke resulting in complete paralysis on his body's left side, will predictably complain about it, as would be expected of anyone. However, about 5 percent of them will vehemently deny experiencing any paralysis in their body at all, a response known as the denial syndrome or anosognosia. These patients will otherwise exhibit normal mental ability and intelligence. The startling discovery, though, was that these patients not only denied their own paralysis, but they also denied any perception of immobility in other patients whose paralysis was identical to their own. Denying one's own paralysis was peculiar enough, but when these patients denied a similar paralysis in other patients, it clearly suggested that there had been some degree of damage to the mirror neurons.

What's the latest thinking in the "nature/nurture" debate?

Every semester, the "nature or nurture" debate inevitably rears its head in every traditional psychology, neuroanatomy, and teacher education course. As the semester quietly ends, so does the still-smoldering discussion pertaining to the dominance of these two developmental factors. Now there is remarkable news coming out of neuroscience that should excite the debaters on either side of this argument -- they are both correct, since the only accurate answer lies somewhere in the middle encircling both nature and nurture. The delicate dance of both nature and nurture determines the end result of each human "product."

All brain development occurs as a complex interplay between the environment into which a child is born and his or her genes. The genetic blueprints for brain and body construction are cautiously monitored in utero as the developing organs, limbs, and operating systems are assembled. Given time, the environment will play an ever-increasing role in the growing young brain. Similar to a massive piece of wood that is destined to be transformed into a statue, the brain undergoes a comparable sculpting procedure, where environmental circumstances whittle away at the raw material and dictate the eventual outcome. Regardless of a parent's desires nurture can only modify what nature had originally supplied. This universal strategy for growth and adaptation will continue for the next seven or more decades.

No human being is ever really quite finished, until the last moments of life. At any given age or stage, he or she is still a work in progress. Genes and environment continue to play their respective roles throughout our lifetimes. Recent research has shown that with every experience, a child's (or adult's) genetically- constructed brain is subject to physical, chemical, and structural alterations based upon any experiences and new stimuli.

During prenatal development, the blossoming fetal brain produces an average of 250,000 new brain cells each minute. There are several points during the process of "neurogenesis" where over 50,000 brain cells are formed every second. By the 20th week of fetal life, over 200 billion neurons have been created. Later, a pruning of these large numbers of cells occurs. Approximately six weeks later, only fifty percent of those cells remain alive. The surviving 100 billion neurons are the healthy cells, which are ready for assignment to a permanent position on an important neural circuit in order to aid the growth and development of the newborn child. The overproduction of neurons and synapses is nature's way of guaranteeing that a child born anywhere in the world, under nearly any circumstances, has the adequate neural wherewithal for survival and successful adaptation.

As new learning occurs, neurons respond by reaching out to one another with their dendrites in an elaborate branching process that connects millions of previously unaligned cells and circuits. The result is the creation of "magic trees," as UC Berkeley's Marian Diamond refers to the dense "neural forests" that are the physiological consequences of stimulation and learning.

The impressive power of the human brain comes, not from the mere numbers of brain cells, but from the constantly changing, infinite number of connections, "synapses," that the 100 billion surviving neurons make as a consequence of genetic programming and stimuli encountered in the outside world. These synaptic contact points between neurons connect one another as well as to the important circuits that represent all human functioning.

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Peter Huttenlocher, at the University of Chicago, was the first neuroscientist to successfully conduct a synaptic census in the human brain. He catalogued the almost infinite junctures (dendrites and synapses) that enable the neurons to communicate with one another. All dendrites, synapses, and their respective connections are so minute and abundant that any pre-Huttenlocher tabulation was based on estimation and speculation, but not grounded in any precise quantification.

any neural advantage over an adult had never been fathomed before. However, Huttenlocher found that the brain of a normal three-year-old child has far more neural connections (synapses) with greater density than the adult brain. In addition, the younger brain consumes 225 percent more energy than an adult brain. Every time the sponge-like brain of a child learns something new, neurons in the cerebral cortex construct new widespread connections to accommodate the newly acquired information, thereby rearranging the operating nature of his or her developing brain.

In addition, the developing brain also undergoes architectural and structural changes based on the new experiences that are processed by the infant brain. When any form of learning occurs, a new series of brain connections is set up within the current framework of neural networks. Those same connections will undergo additional alterations later with still newer input. The trillions of linkages give the brain its amazing capacity to process and store information in a fashion that renders its learning potential virtually unlimited. Thus, the more we learn, the more we are capable of learning in the future, particularly if that new learning is similar to any previous knowledge or skill.

All postnatal experiences serve to shape the brain and to reconfigure it regularly and faithfully as one's personal biography continues to carve the three pounds of malleable brain matter into a distinct human being and one who functions quite well within the parameters of his or her exclusive surroundings. Until death, the brain is never actually finished building, rearranging and reconstituting itself to orchestrate our continued existence.

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Do we really use only 10 percent of our brain?

As a possible spillover effect from the "left-brained/right-brained" craze of the 1980s, we still hear assertions that human beings use only 10 percent of their brains. The statement implied that some gifted scientist had already been able to accurately calibrate the brain's maximum operational capability. There is not a single neuroscientist who has quantified the brain's extensive aptitude. Thus, any claim to have measured 10 percent of this truly mysterious quantity is worthy of extreme suspicion.

What neuroanatomists do know is that there was a high physiological price to pay during cephalization, the evolutionary process by which neurons began to concentrate around the head region of primitive invertebrates. A higher level of cephalization developed in the more advanced invertebrates, and in the more complex brains of larger more sophisticated vertebrates, like our early hominid ancestors three to four million years ago. This developmental course resulted in a considerably larger human brain, and a correspondingly larger cranium in which to house it.

An unavoidable consequence of the new human talent to use language, create tools, and function in complex social arrangements was the gradual enlargement of the human brain. Not only did we enjoy these new skills, but they were also accompanied by early man's revolutionary proficiency in bipedalism. Unfortunately, becoming a bipedal vertebrate with the ability to walk upright had its downside for early woman. This capacity was evolutionarily beneficial in finding food, identifying mates and children, locating enemies, etc., but it caused the human pelvis to grow narrower to support walking erect. As the pelvis and hips contracted, the birth canal grew narrower. Had the reverse conditions prevailed -- the human head getting smaller as the dimensions of the birth canal increased -- the challenge of childbirth would be largely absent. Instead, a larger cranium was required to pass through a slowly constricting birth canal. An infant's head is now frequently 102Ð103 percent the size of the birth canal. The evolutionary "correction" for this dilemma was to require a greater proportion of human brain development to take place in the post-natal periods. The human burden was unlike most other newborn animals and mammals, which are "geared to go" only hours after birth.

Thus, human beings are among the most helpless creatures on earth immediately following birth. Twelve to fourteen years must pass before a child can satisfactorily care for himself and function independently. Of course, most parents of teenagers and young adults might take issue with the figures of twelve to fourteen years, considering these to be wildly optimistic numbers, since the parental "time investment" for contemporary American and Western offspring has been greatly extended. The sustained care for our children, in many contemporary cases, seems endless.

During the years that the brain competed with other organs in the body for a favored position in the body's functional pecking order of importance over the past four to five million years, the brain's volume crept forward and finally saw a 350 percent increase in size. Consequently, the human brain has become became an extremely "high maintenance" organ. When body weights are plotted against brain weight, animals with high brainÐto-body ratios are quite atypical. Here is the question begging an answer: Is the brain an evolutionary luxury that continued to consume vast amounts of resources (nutrients, energy, and oxygen) unchecked by the omnipresent evolutionary monitoring systems? Evolution was never known for its compassion and generosity. Instead, it operates by the more economically rigid use-it-or-lose-it principle. From this standpoint, a brain that is used only 10 percent of the time (and therefore useless during the other 90 percent) would have never passed the millions of years of scrutiny nor would it have been tolerated over such a lengthy time span of ongoing evolutionary assessments, analyses, and adjustments.

New brain-imaging evidence convincingly dismisses all notions that only 10 percent of the human brain is used at any given time. In PET scans of any activity including thinking and sleeping, the entire brain "lights up" with vivid reds and yellow indicators that visually identify a great amount of cortical activity taking place in nearly every area of the brain during the execution of just about all cognitive tasks. More than 60 percent of the brain is highly active even during the course of REM (Rapid Eye Movement) sleep or dreaming.

In the devastating cases of brain disease and trauma, we only yearn for the day when 90 percent of the brain had been held in reserve, which would surely guarantee all restoration of brain functioning following strokes, missile wounds, and automobile accidents. Not a single medical case has ever demonstrated that an individual was capable of functioning after losing 90 percent of his or her brain. In matters of the brain, the contrary is more accurate. There is no known region of the human brain that can sustain considerably low levels of damage without an extensive loss in mental capacity or major functional changes evidenced by vast difference in one's behavior. Recovering 100 percent of an individual's pre-injury or pre-operative abilities seldom occurs.

Some neuroscientists have traced the "10 percent legend" back to early neuroanatomists, who were only able to identify approximately 10 percent of what the various parts of the brain actually did, which led others to infer that only 10 percent of the brain was actually functioning. Since only 10 percent of the brain had been mapped out and accounted for, many concluded that only that amount was ever subject to use. Later came the ads and programs claiming, "You, too, can use more than the typical 10 percent of your brain, if you buy my miraculous brain-enhancing products, books and tapes for $499!"

Still, important questions remain. How much of the brain's capacity do we use? Can we develop a brain to its full potential? What can be done in a classroom to maximize the development of a young brain? How can we keep an adult brain performing at its highest levels for a lifetime?

At this point, no definitive answers are available.

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What's the connection between brain plasticity and learning?

Alvin Toffler, the noted author, said, "The illiterates of the future are not those who cannot read or write, but those who cannot learn, unlearn, and re-learn." But what happens inside of the human brain to foster those events commonly described as "learning"? In order to avoid being among those illiterates of the future, how should we modify our classroom instruction so that it conforms to the latest research findings concerning the human brain?

Some of the best of the recent good news about neurons is found in this notion of cortical plasticity. The brain can literally change the functional qualities of various brain regions depending on the regularity and type of new tasks that the local neurons are asked to discharge. The bad news is that any of the seldom used or unused neural networks get unceremoniously purged especially during those early pre-pubescent years. Some specific skills can be lost forever if they are not cultivated during especially sensitive first years of life.

Cortical plasticity refers to the brain's ability to continue exercising its flexible nature by allowing different areas of the brain to change their function or structure as a result of new experiences that the brain gets from the outside environment. The brain is not only sturdy, but it is also delicate and flexible. A child's early interactions directly impact the ways in which his or her brain gets physically connected or how it gets "wired" initially. With the acquisition of new knowledge, the elaborate networks and structures inside the brain go through modification, re-organization, and cellular adjustment. Those changes are reflected in tangible transformations in the brain.

At the earliest stages of infancy, not only are all children biologically ready to learn from their stimulating environment and their interactions with other people, early brain development requires this. Healthy brain cells will perish if they fail to find a job to carry out during these critical early developmental periods. The lack of visual stimuli during infancy can permanently rob a healthy eye of its ability to see. If a child does not hear words by age ten, he or she will have a difficult time learning to speak any language at all. Neurons that should have participated in the language processing, but instead find themselves lacking a role to play, have only one of two options. They will be recruited to support another function with a different neural circuit devoted to a contrasting specialty, or they will experience apoptosis, cell death. In brain terms, neuronal death occurs via a self-induced cell-suicide. In the case of language, the remaining brain cells that specialize in language processing are well fed and well nourished for most of one's entire life. The others are gone forever.

The ways in which the brain is stimulated (or not stimulated) will determine the cortical complexity of any region in the brain, which is measured by the number of synapses and the nature of their connections to the various other parts of the brain. Brain cells constantly rearrange their one quadrillion-plus connections in response to extrinsic circumstances. All new learning, the external or internal stimuli that the brain encounters, promotes additional changes in the brain. In doing so, areas of the brain can adapt to any surroundings, quite different from other animals, which operate solely by instinct and do so only within specialized, limited environments. Human brains can adopt new functions based on the quantity and the quality of input received and processed by the brain.

In the 1980s, UC Berkeley's Mark Rosenzweig discovered that a rat's environment affected both the weight of its brain as well as the quantity and density of connections between and among its neurons. These are considered the best indicators of a rat's ability to learn new skills or information. Boosting the immature brains with excessive amounts of growth hormones can also increase the number of neurons in rats.

High levels of stimulation and numerous learning opportunities at the appropriate times lead to increases in the density of the neural connections (the dendrites) and more brain real estate devoted to an emerging talent. Howard Gardner's theory of multiple intelligences identifies eight forms of human intelligence. Each of these intelligences comes with a matching primary area of the brain that houses the cortical representations, executes the motor outcomes, and is connected with its myriad associated areas. None of the multiple intelligences will unfold naturally until the appropriate environmental conditions are present to allow that talent to develop and flourish. In a model environment, one's gifts, skills, talents, and aptitudes can be maximized by regularly stimulating them all as frequently as possible in cooperation with the appropriate set of genes.

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In human beings, one's level of expertise shows itself by means of cortical distinctions in the brain, and major differences in the neural representations of the very same information, when we compare brain-images of "novices" and "experts" performing precisely the same task. Their differences are vividly apparent. Experts organize, process, and interpret information in their brains in ways that are different from non-experts. Following additional input, that information is represented differently in the brains of those members of each group. Cortical variations are even observable in the neural networks accompanying the development of a specific talent that an individual cultivates over time.

For instance, when comparing three pianists with varying backgrounds, we can detect their distinct cortical differences. The pianists are a thirty-year-old who began piano lessons at the age of four, a thirty-year-old who casually took up piano at age twenty-eight, and a highly motivated nine-year-old novice who has been playing piano for slightly less than a year. All three pianists can play the exact musical piece, but each of the performances shows completely different neuronal activities taking place.

The areas in their brains that represent finger movements (the motor cortex) in each hemisphere of their brains are different. The regions of the cortex that handle the reading of musical notations are also different. Different neurophysiological circuits represent the different aspects of how that particular song is processed in their brains and performed by their bodies. The sorting and processing of particular "musical performance" neural data all flows more freely between the cortical areas of the brain in the more adept and well-trained "expert" brain. The attentional efforts are significantly less for the expert, who studies the notation far less than the novice. Their cortical differences can now be evidenced both in the performance quality as well as through brain imaging techniques.

In an experiment, expert chess players and novices were asked to memorize random chess pieces on a board. Under these conditions, the experts performed no better than the novices. However, when the chess pieces were in "game positions" that might replicate positions if two players were in the midst of a challenge, the experts' recall of the location of each chess piece far exceeded that of a novice. The ways in which the accomplished players organized the information was clearly unlike the emerging organizational talents of players with no prior chess experience.

In education, a novice teacher and an experienced teacher will scrutinize the same classroom events and assign contrasting instructional significance to many of them. When at home or outside of their classes, encountering information that can potentially improve preparation and instruction will often be acknowledged by the expert teacher, but overlooked by the novice.

We see identical events taking place in reading and language arts classes. There are students with natural advantages in linguistic capabilities and skills (girls), sitting next to students with limited experiences in the language spoken in class (the foreign-born student), as well as children who have had absolutely no personal experiences that relate to the contents of the story nor familiarity with the language. For example, the story can be about yachting and a student's limited inner-city life has never taken him to a harbor, let alone sailing on a boat of any kind. The linguistically different student cannot transfer any appropriate language from his or her native tongue to the yachting experience and is at a tremendous conceptual and language disadvantage. This student can be contrasted with those whose parents read to them at a very early age and who also demonstrate a more sophisticated usage of the language, which correlates to the language that is used by the teacher, found in the textbooks, and used in standardized testing.

The manner in which fictional stories are pro-cessed in the brains of students in each of these groups will vary drastically, as will the level of detail in recalling a story and its composing elements. Meaning is not conveyed; it is evoked. Activating the appropriate neural pathways for reading and understanding a given passage assumes that a child has already developed the corresponding schema (the necessary background knowledge) fostering those neural connections. The human cortex operates best by patterns, not by facts. But the patterns must make sense or the individual facts are the first casualties in tests calling on one's memory. Information that is difficult to comprehend or that has no meaningful context for an individual's neural networks will be information that is difficult to link to any long-term memory circuits. As a result, the idiosyncratic human brain and the manner in which we deliver formal instruction reveal major design flaws. These known facts partially explain the successes and the failures regularly seen in classrooms, particularly in the primary grades.

The experiential paradigms of two people offer a similar contrast. Should they watch the same movie about a man escaping through the jungle, the first person might find the film entertaining, while the second finds it quite disturbing. Knowing that the latter individual survived the Khmer Rouge in Cambodia (the so-called "Killing Fields") will help us understand the differences in their two brains processing precisely the same movie at exactly the same time. When a class of students reads the same material, although the words and pictures are the same, the schools must begin to acknowledge that a vast range of individual experiences, cortical representations, and variations in brain circuitry will generate different learning results. As a consequence, some students will relate to the content material well and remember it easily. Others might remember little or nothing. The way new material gets processed and connected inside the brain makes comparing one student's performance with another for grading purpose an effort that defies logic. Such a system for grading students has all of the trappings of fool's gold. We live and exist sometimes in completely different cognitive worlds that have shaped our brains into markedly diverse organs. Such variation defies the simplified classroom comparisons that are holdovers from the school-as-factory model designed to mass-produce knowledge.

This is not all there is to say about brain plasticity. There are interesting new studies that suggest -- contrary to the eons-old "neuro-dogma"-- that we can generate new neurons and that pinpoint particular growth spurts for brain activity. Between the approximate ages six and puberty, for instance, the parietal lobes begin to show a great amount of activity. During this time, the skills for developing language and spatial relations reach their construction "peak." At the end of this period, the impressive growth and connecting rate falls off quickly. After puberty, mastering a new language becomes enormously challenging and any new language will be accompanied by an accent, which cannot be changed once this window for language construction has closed.

Immediately prior to puberty, another spurt in brain cell activity takes place in the frontal lobe (at age twelve in boys and a year earlier in girls). These neural construction projects are suddenly and strangely placed on hold and there is a substantial loss in the frontal lobes for close to a decade beginning in the mid-teen years.

A generation ago, we would cautiously speculate about neural activities and the corresponding structural transformations. At that time, our best evidence came from investigations permitted only due to misfortune or through autopsies. Today, not only can we observe brain plasticity, but we can also capture it pictorially with non-invasive brain-imaging techniques using perfectly healthy subjects, where we leave neither side effects nor scars.

In the last five years, we have learned more about the human brain than in all of our previous history. Daily, we continue to learn still more about the human brain and its amazing capabilities as well as its delicate functioning. It is our hope that educators and parents will soon put this exciting new information from neuroscience to its most profitable advantage in the home and the classroom. Each week, over 80,000 babies are born in the U.S., giving us 80,000 more opportunities to utilize the ever-expanding knowledge reservoir in brain research. By using this information, we can build better baby brains, better learners, and one hopes, a more brain-considerate system of formal education.

[Please remember to read Parts II and III of Kenneth Wesson's article in the Winter and Spring editions of Independent School.]

Kenneth A. Wesson is an educational consultant living in San Jose, California. He speaks throughout the world on the neuroscience of learning and methods for creating classrooms and learning environments that are "brain-compatible." He also lectures on the subjects of emotional intelligence, diversity in learning, and early brain development.

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