Memory and the Brain

Editor's Note: This is the third in a three-part series on recent brain research and its impact on teaching and learning. Part I, What Recent Brain Research Tells Us about Learning, appeared in the Fall 2001 issue. Part II, Where Is God in the Brain?, appeared in the Winter 2002 issue.

Prior to addressing a conference for educators and administrators in sub-Saharan Africa a year ago, the absolutely profound beauty of non-Western thinking had never been quite so obvious to me. In several regions of Southern Africa, a single word exists for both "teaching" and "learning." In the Western mindset, we have separated the two, as if they were distinct functions unto themselves. We often hear educators lament, "I taught it; they just didn't learn it!" However, within the insightful African context, when learning does not take place, then the instructor has not yet completed the important "teaching component," rendering the learning equation fragmented and unfinished.

From tribal elders to master tradesmen to university professors to kindergarten teachers, all "teachers" have noticed that learning often depends as much on certain attributes of the learner, as it does on the nature of the knowledge at stake. It is also clear that some teachers are very good at tapping into these learner attributes to assure effective understanding, while others struggle despite their own knowledge of a given subject.

The primary function of the human brain is to encode, process, dissect, distribute, store, retrieve, and use information for survival or emotional fulfillment. For most of the mid-20th Century, under the influence of psychologist B.F. Skinner and other behaviorists dominating the field of psychology at the time, we oversimplified these complex brain functions. Whether the spotlight was on pigeons depressing a lever to receive food pellets or on multifaceted issues, such as the elaborate process of language acquisition, the deliberations were commonly forced to fit into Skinner's Stimulus -› Response model. Conversations about teaching were also frequently reduced to this same model. Such oversimplification became almost unavoidable, considering that behaviorists influenced most views on thinking and learning during those decades. However, we now recognize a host of additional factors that undeniably influence the outcome of human learning and/or behavior.

Student history has consistently recorded evidence that learners don't obediently "respond" to new information simply because they have been exposed to it. Formal education, to say nothing about parenting, has never been characterized as such an effortless venture met with instantaneous success implied by the Stimulus -› Response model. According to distinguished educator Art Costa, teaching is considered to be among the most demanding professions in the world because of the innumerable variables that are not captured in a simplistic Stimulus -› Response framework (see "Factors Governing Learning and Behavior" above). Instead, the challenges facing educators are found in the intermittent and sometimes permanent brain-based obstacles that stand firmly between one's dedicated teaching efforts and the sometimes unpredictable student outcomes.

Prior to entering kindergarten, a child's personality and temperament are well established. That child's ability to learn will be a function of the following factors:

• Whether the child is a male or female;
• His/her access to proper nutrition during prenatal development;
• Genetic deficiencies and assets;
• The amount of postnatal care given to the child's health concerns. (This would include, among other things, simple hearing tests to detect early central auditory processing disorders, which can lead to early language problems.); and
• His/her emotional development and current emotional state. Emotions, in many ways, dictate whether the child has any interest in the subject at hand, and is even willing to pay attention. They also determine whether or not a child can remain focused on the subject and not be easily distracted by other personal and emotional intrusions. With the more extreme emotional states, such as living in a highly stressful environment, children are frequently more prone to focus on any perceived threat -- be they physical, emotional, psychological, or intellectual -- rather than on the less significant academic focus of the day. (For a more detailed discussion of emotions and learning, see "Where Is God in the Brain?" Independent School, Winter 2002.)

These considerations extend our understanding (beyond the artificial parameters presented by the simple Stimulus -› Response equation) of the relationship between learning and the myriad factors that affect it -- whether in the classroom, the home, or the workplace.

Normal human brains are lopsided. The left hemisphere is generally larger and more active than its right counterpart. Paula Tallal, of Rutgers University, and others have noted that whenever the two sides more closely approximate symmetry, the left hemisphere is usually somewhat underpowered. This neurophysiological downside is suspected as a leading cause in incidences of language disorders. In females, the left hemisphere is noticeably larger than the right. However, the male brain appears slightly more symmetrical because the average male brain comes equipped with a larger right hemisphere than would be typically found in females. In addition, females average approximately 11 percent more brain cells than males, giving them a distinct neurological advantage in language-related abilities.

It is no coincidence that more than 80 percent of the cases of developmental language delays -- dyslexia, stuttering, and other language-related problems -- afflict boys. Travel anywhere in the United States and one finds that nearly 80 percent or more of the children enrolled in remedial reading classes in the elementary grades are boys. In middle and high schools, the figure climbs to slightly above 90 percent. More than three-quarters of the men in America's prisons have a severe language, reading, learning, or hearing problem, or some combination thereof. Over the course of 12 years of formal education, a 1.7-year gap in language fluency typically separates boys from girls, along with a three-year performance gap in written language.

Memory

Memory is a biological event involving the activation of several brain systems. Our memories are not situated in only one brain structure or in a single place inside the brain. For any memory to be created, it is necessary that neurons form new connections via synaptic linkages with other neurons. Combined, these neurons will represent the elements of an experience or idea. In order for information to be remembered, it must be encoded and processed by the neurons.

Physiologically, we cannot store and recall ("remember") information that has not been properly attended to and encoded by specific regions of the cerebral cortex. The brain translates incoming data into the digestible fragments needed to reconstruct a mental representation. The manner in which one encodes and records information will govern precisely what is later remembered and how the information will be recalled, if it can be consciously recalled at all. A student will remember information best if he or she can use the same techniques in retrieving the information that he or she used initially to encode it, and if he or she has a personal/ emotional connection with the target information.

Poor memories are often the product of ineffective initial encoding, which usually occurs because little attention is paid during the initial encoding and processing phases, where no personal/emotional linkages are established. When asked to identify the only accurate picture of a U.S. penny on a page with nine other choices, very few people can make the correct selection from the sheet with nine imposters. Although most adults have likely seen and held over 10,000 pennies during their lives, few can pick the correct picture. The reason for this is simple: We don't really care enough to memorize what an exact reproduction of a penny looks like since a penny has such little personal value. With over ten thousand exposures to the stimulus, the response is still inaccurate without a personally motivating linkage to details in the coin. There are two groups of people who can make an accurate identification of the penny. They are either professional coin collectors or penny-pinchers. When there are emotional "hooks" planted for the learner, the probability of subsequent recall increases dramatically.

When one broadens the mixture of the modalities by which information is encoded, more neural avenues for retrieving it are simultaneously created. All memories are aided by the introduction of multiple methods available for their retrieval. This is why teaching a concept several different ways (do it, touch it, say it, hear it, write it, and read what others have written about it) is vitally important for satisfactory student recall. Doing so might require additional instructional time, but it constitutes a wise investment of teaching time. "Shortcuts" in teaching -- such as straight lectures -- can actually take longer when teachers find themselves going over material again and again, frustrated by the fact that students don't seem to be able to remember much.

Whether we actually ever forget anything or whether learned material simply becomes increasingly more difficult to access from our neural networks is still the subject of spirited debate. What we do know is that, as we age, retrieval of information becomes more difficult. We also know that, in the absence of any personal/emotional hook, the likelihood of "forgetting" rises. It is also interesting to note that, within the first two days of an incident, we typically have difficulty recalling more than 20 percent of what was learned. This is because the brain will process and even learn a great deal more than it can retain for long periods of time (thus, we use notepads, audio recorders, computer disk drives, palm pilots, etc., to assist us with our heavily-taxed memory systems). We forget things quickest shortly after we learn them, which is why we must download that information to maintain it.

Some faulty memories are attributable to faulty "wiring," which can often be a consequence of damaged nerve cells from trauma (an injury to the brain), high fever, disease, etc. -- each of which can disrupt a previously functional brain circuitry. Damage to the myelin sheath (the insulation/covering on the exterior of an axon found on a typical neuron) can disrupt the electrical signal, thereby interrupting the entire system of networks containing the memory. The demyelinating diseases, such as multiple sclerosis, will accelerate the destruction of the neural circuitry necessary for appropriate brain functioning.

Ordinarily, we do not forget something in its entirety. Instead, memories go through a "graceful degradation." As many people over 40 will attest, there is a decrease in memory performance -- known formally as age-associated memory impairment (AAMI) -- that accompanies more than four decades of processing and storing information. Memory is still retained; it just takes more time recovering the sought-after memories, its details, or related facts, as we must sort through the massive number of other mental files and neural connections representing our 40 or 50 years of accumulated information. Processing rates are also part of an overall slowdown in functioning and age-related responsiveness. We don't run as swiftly. We don't jump as high. We move more slowly, and recollections take more time to reconstruct than they once did. These are all normal parts of the benign course of aging.

Octogenarians, who can remember every detail of their wedding day or high school graduation, often cannot remember whether they took their medications that very morning. We can vividly remember the name, face, voice, and kindness of a teacher who took a true interest in us back in elementary school, but we can't remember where we parked our own car at the shopping mall one hour ago. This is because it is the emotional connections that determine what we choose to remember and what we elect to disregard. The noticeable challenges to one's recall have more to do with confusion and stress than they do with "senior moments." Children in elementary grades often forget their coat at school or their homework on the kitchen table. No one ever blames these events on "elementary moments." Various levels of MCI (mild cognitive impairment) are evident at all brain stages and ages.

Capitalizing on the human senses to promote learning

We know today that, during infancy, the processes by which young children begin their acquisition of the earliest forms of knowledge are rather similar. Children, as well as other mammals, begin their earliest learning through exploration and play. Psychologist Jean Piaget described play as the serious business of childhood learning. Youngsters also learn via a genetically predetermined sequence of skills that are mastered based on how and when different structures composing the human brain go "online." Once born, the young human brain is so responsive to external stimuli that we can now safely say that nearly all early experiences contribute in shaping a child's growing brain. These sensitive developmental processes transform and "tailor-make" one's neuroanatomy. They also eventually determine the regional functioning capabilities in an individual's brain.

When new learning occurs, the brain changes physically. The very architecture of each human brain is altered as a result of all newly acquired skills. The unfolding events one experiences in life largely decide how much cortical growth will take place, in what regions that growth will take place, and when, if, and where subsequent development will occur (or not) in a blossoming young brain.

Many new competencies are often accompanied by a series of "brain spurts" that are fixed primarily by genetic programs (see "The Seven Brain Spurts" on p. 86) in which parts of the brain mature and a greater amount of myelination takes place in the maturing regions. Initially, a child's brain has twice as many neural connections as the brain of an adult. Recognizing that early exposure to a wide range of learning experiences has a positive impact on brain development, we are now taking a closer look at the critical role that early cognitive development should play in preschool and day-care programs. These years are not just the "developmental years." They constitute the optimal incubation periods for developing the fundamental skills needed for successful kindergarten through college-level learning.

Multisensory experiences further extend these precious and plentiful connections throughout the cerebral cortex. Since it often takes six exposures (hearing, saying, touching, seeing, etc.) before new information enters into long-term memory for permanent cortical storage, combining multisensory with multimodal approaches will reach nearly any student's learning preference or cognitive learning style.

Increases in both the size and the weight of the brain are among the many expected neocortical results of learning and memory formation. The more frequently a given network of neurons fires together, the greater the likelihood it will later become permanently hardwired. Conversely, diminishing one's learning opportunities will reduce the quantity of neural networks, which will often permanently decrease one's ability to learn. However, the human brain is more than capable of developing trillions of interrelated neural networks rendering our capacity to learn virtually limitless -- if we choose to continue stimulating and challenging the mind.

Experience and Learning

Albert Einstein said, "Learning is experiencing. Everything else is just information." His insight suggests that we must "experience" our learning by using our complex sensory systems. Our species has an innate need to see, touch, taste, feel, and hear the features of any new object in order to understand it better. There are teaching techniques that cater to the brain's natural inclinations for learning new skills, storing skill-related data, and knowing when, where, and how to reach into one's cognitive tool chest to utilize the previously gained knowledge in efficient ways. There are effective strategies that facilitate learning, and these strategies, in many ways, mimic the sequential strategies used by all learners as they naturally mature.

Our brain and skin start out initially as the same primitive formation during prenatal development, but they are separated during one of the earliest stages of neurogenesis. Thus, in a sense, our skin is the "other half" of our brains. This is why, at nearly all early phases of one's development, a great deal is learned about the environment by the act of touching. As a result, the highest rated school activity for American children is none other than "show and tell," during which children get to feel and touch something that has high emotional connections to a classmate, the perfect equation for attention-getting and subsequent learning. When touching an object, most higher-order mammals will also turn it, twist it, view it from a number of positions, while drawing the most meaningful clues, cues, and relevant information needed for drawing conclusions concerning that object.

The first of the more prominent five human senses (so far, 19 senses have been identified, not just five) to come online in the human brain is the sense of touch, which for both sighted and blind individuals serves as one of the earliest and the most fundamental methods of data collection, knowledge acquisition, and decision making. Objects with which we have had direct first-hand experience are the objects about which we are most capable of discussing, writing about, reading about, and explaining to others. This is perhaps one of the most substantive reasons why first-hand experiential learning has always been one of the most powerful methods of sustaining the cerebral circuitry for any particular kind of knowledge residing inside the human brain.

When new concepts are registered through varying modes of learning, those concepts are stored in several interconnected neural networks, and the cerebral cortex establishes numerous physiological "access routes" back to that specific concept. Concrete learning experiences (for both children and adults) provide the most substantive basis for concept development, conceptual understanding, and the potential for concept extension. In particular, hands-on/ minds-on learning opportunities make possible the subsequent comprehension of abstractions and foster the creative thinking processes. The mental constructs derived from first-hand experience later serve as the foundational basis for hypothetical constructs ("what if" questions), leading to the highest levels of cognition.

The human senses firmly set the boundaries for all of our experiences. For example, there are neurons (the brain cells that make up the fundamental communication systems in the human brain) that are capable of processing sounds within a particular range. Sounds outside of those limits are beyond the processing capabilities within which our sensory systems operate. If our senses cannot detect and report on an event, we are typically oblivious to it. However, we can extend those otherwise fixed borders with sensory-expanding apparatuses such as microscopes, telescopes, telephones, eyeglasses, hearing aids, and other sensory-enhancing equipment.

In the sensorimotor cortex, there is a personalized, detailed physical map of each individual's entire body referred to as the "homunculus." There is an interesting method by which the brain oversees the distribution of cortical real estate. There are more neurons and more cortical "space" designated for certain areas of the body. The undemocratic assignment of cortical territories is initially based on the degree of importance that a given area of the body has in relation to one's survival. However, the brain is not a static organ. Later, the allocations are, gradually but regularly, reallocated as a consequence of how frequently a particular area of the brain is used, how its related functions are valued in one's specific environment, and its importance to survival and emotional fulfillment.

Until the late 1990s, it was thought that the homunculus was fixed for a lifetime, and identical in all human beings. However, each individual's homunculus gets tailor-made based on personal experience; it's as unique as one's fingerprint. Tiger Woods' homunculus would show greater representations in the motor areas that were fine-tuned to perfect his incredible proficiency in golf. The brain of a professional violinist shows a greater amount of the motor cortex devoted to finger movement in the left and right primary sensorimotor areas than one would find in the average person or in any non-musician.

Recently, Michael Mercenich, a neuroscientist at the University of San Francisco's School of Medicine, demonstrated that the homunculus not only varied between different monkeys of the same species, but that the cortical representations in a monkey's homunculus could also be altered by engaging the monkey in a series of new tactile experiences controlled by the laboratory researchers. Rockefeller University's Hiroshi Asanuma discovered that the neural connections in the sensorimotor cortex could be increased by as much as 25 percent as a result of training monkeys to catch their food with just the index finger and the thumb of a single hand. Once a high level of proficiency was reached, there was a neurophysiological correlate representing the changes that had taken place inside the brain. Those changes made the new high-level performance and the new degree of expertise neurophysiologically possible.

If a region of the motor cortex responsible precisely for right-hand movement in a human is damaged, the use of his right hand will be substantially diminished or lost completely. Conversely, if movement in the right hand is grossly limited or completely restricted (to a level of non-use), the cortical regions of the brain responsible for movement in that hand will atrophy, as the neglected neural networks begin to shut down the operating circuits inside the brain. Interestingly, the cortical areas representing the opposite (left) hand will often increase to compensate for the loss of right-hand use and a marked improvement in left-hand dexterity and proficiency will take place. This phenomenon, "compensatory hypertrophy," is how all brains physically reorganize themselves in such a way that the opposite hand (or leg, or eye, etc.) gets stronger as a response to the lost service of its counterpart. By doing so, one can always adapt to life's changing conditions and one's chances for survival are enhanced, as the brain modifies itself -- always looking towards survival and the future.

Conclusion

The rapid advancements in brain imaging and computer technology have served to accelerate new insights into how the brain "works." Today, there are more than 500,000 brain-related websites on the Internet. Cyberspace has become an invaluable resource for data gathering and distribution and has contributed substantially to the expansion of today's impressive knowledge in neuroscience. The Internet's unrivaled use and ubiquity have also played a major role in creating the ever-expanding interest on the part of educators and parents to learn more about the developing young brains around them.

In addition to our increasing level of knowledge, many of our contemporary medical tools and techniques have become so easy to manipulate and maneuver that a medical journal recently reported that the average adult could satisfactorily perform an appendectomy after only three days of training. (Not that any of us should seek out such an amateur surgeon). The important point here is that we are in the midst of an unprecedented knowledge explosion in neuroscience. With the latest brain-imaging methods, we can see the neurophysiological correlates to countless human activities and experiences.

With the momentum that the field of neuroscience is currently enjoying -- particularly given its far-reaching implications to learning -- education and nearly every other aspect of our human existence will be enhanced. The broad field of education will be among the first and greatest beneficiaries of this research. Members of the general public can even expect a better understanding on how one might forestall the ravages of Alzheimer's disease and other indicators of the benign course of aging that seemingly have become inevitable events associated with aging.

While students come in a variety of colors, all brains are basically gray. It is only the gray matter that truly matters in learning and neuroscience. Maximizing the potential of each and every human being in the classroom hinges on developing a working knowledge of the mammalian cerebral cortex, of how the brain works. I hope that understanding the inner workings of the human brain will become a prerequisite for teaching in the coming decade. The extent to which educators and administrators regularly apply this research will impact not only the future of our students, but the future of humankind as well. Whatever role one plays in a school, it is a vital role in the world's most important responsibility -- teaching the next generation to thrive on Earth.

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-considerate."

The Seven Brain Spurts

1. The first brain spurt takes place during the delicate brain-building process and the subsequent purging process (when the least-used nerve cells and brain circuits are extinguished), during gestation. Prenatal substance exposure can trigger a devastating disruption of these important early processes resulting in long-term brain impairments (e.g., FAS - fetal alcohol syndrome - and neurological/performance deficits caused by poor early nutrition).

2. Adjustments to one's particular environment will affect the postnatal cortical alterations during the first three years of life. The basic sensory systems come online early during the first year of life. Although the cerebral cortex grows rapidly during the first two years, the pace of growth in the cerebellum far outstrips the remarkable growth trajectory of the cerebral cortex. The quick maturation of vital survival skills takes priority on the infant's early developmental schedule. Here, crucial neural systems get switched on or not depending on the quality and quantity of sensory input received by the infant from his environment. The functioning of our sensory systems are extremely imprecise in their early stages because they are still cross-wired and in need of maturation and experiential refinement. As a result, infants can experience "color" sensations when they hear sounds. They can "taste" vibrant colors, when they look at a brightly colored object. This phenomenon, "sysesthesia," is characterized by an intermingling of the senses giving infants an "ultimate" sensory experience from even mildly mundane sensations.

3. A fine-tuning of a child's emerging skills takes place between the ages of three and six. Around age five or six, the brain has reached 90-95 percent of its adult volume and is four times the size it was at birth. Ages three to six are the years during which extensive internal re-wiring takes place in the frontal lobes (the cortical regions involved in organizing actions, planning activities and focusing attention).

4. Between approximately age six and the onset of puberty, the parietal lobes begin to show a greater amount of neural activity. During this period, the skills for developing language and spatial relations reach their developmental and construction "peak." At the end of puberty, the impressive growth and rate at which new connections are created to facilitate language fall off quickly. After puberty, the mastery of any new language becomes incredibly difficult as a result. Even when it is learned, it will almost always be accompanied by an accent.

5. Immediately prior to puberty, another burst in brain cell activity takes place in the frontal lobes (at approximately age 11 in girls and a year later in boys). These neural construction projects are suddenly and strangely placed on hold, during which time there is a substantial loss in the frontal lobes for a decade beginning in the mid-teen years.

6. Wholesale renovations take place during puberty and the late teen years (hormonal changes, alterations in the body's biochemistry, physical growth spurts, etc.). These massive reorganizations are so physically incapacitating that there is now an increasing awareness of why teenagers (like chemotherapy patients) need more sleep/recovery time, which legitimizes a later starting time for middle- and high-school students.

7. The final brain renovations occur during adulthood. While the size of the adult brain decreases slightly, the trillions of connections continue to rearrange themselves constantly in our multifaceted roles as parents, workers, researchers, job-changers, spouses, etc., in our ongoing effort to adjust to our changing lives and our changing environment. Recent research has shown that the adult brain makes dramatic neurophysiological changes between ages 30 and 70. This discovery has shattered many of the traditional beliefs about adult neurogenesis and neural plasticity in older persons.