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I began thinking about the concept of a memory advantage more than fifty years ago at St. Mary's School in Baltimore. My blessed but much feared third grade teacher, Sister Martha, had been teaching multiplication tables for quite a few weeks and was conducting speed drills by calling out multiplication problems. As she called out each problem she walked up and down every row in the classroom, ruler in hand, listening for tardy or incorrect responses. I had made a gentlemanly effort to learn the tables and was quite confident in my abilities to remember them ... as long as one of the two numbers being multiplied was four or lower. I had every intention of moving into the higher columns in due course, but had not yet found the time in my schedule. After only a few problems into the exercise, the chilling sound known to every Catholic School child of the day crackled through the room: that of ruler meeting knuckle. Suddenly, I regretted my hours watching Western movies or playing baseball after school. I vowed that, if only I could escape this exercise, I would go straight home and devote my life to arithmetic memorization. First, though, I had to conceal my less than perfect mastery of the multiplication tables. Simply moving my facial muscles was adequate so long as Sister Martha was on the other side of the room, but as she approached and focused her intense green eyes directly on me I could only hope that through divine intervention, at least one of the two numbers in the problem she was about to pose to me was four or lower. My palms began to sweat and I could feel my face turning red as I watched the numbers form on Sister Martha's lips. "Four times four" she shouted. As I confidently shouted back "sixteen," I felt the greatest sense of relief and elation imaginable. Either divine intervention or just good luck had saved me from an embarrassing and painful memory failure, and I vowed that after that afternoon's baseball game and 5:00 television Western I would learn the multiplication tables perfectly, and gain a memory advantage for Sister Martha's next sadistic arithmetic exercise.
There are many Sister Martha characters in the memory of all of us educated before today's kinder, gentler age of education. Back when rote memorization was the primary means of teaching almost everything, teachers were generally unconcerned about self-esteem and providing everyone with a good grade. Failure to memorize the facts you were taught led to punishment of one sort or another, usually including social ostracization. Of course what we recall must have been enlightened compared to earlier years because I do not recall a "dunce cap and chair," and the principal's paddle, while still a visible reminder of authority, was rarely employed, at least in the schools I attended. Even in schools today there is little alternative to rote memorization of a great deal of material and the consequences of poor learning and memory abilities become apparent early in childhood.
In some children, a memory advantage is provided genetically. Many years after Sister Martha, when I was a much more diligent student who actually studied the information to be recalled on a test, I spent hour after hour at my desk studying, which meant principally trying to memorize information. It seemed to me that it took me three or four hours, and often more, to memorize what a few of my friends could memorize in the classroom, without any homework at all. It was clear that my memory advantage was not going to come from genes. What followed was many years of simply spending hour after hour learning and memorizing written material.
So, a memory advantage can come from genes or from hard work, but it can also come from understanding more about the psychology and neurophysiology of memory; changes in memory that occur across the life span; medical, psychological, and lifestyle issues that affect memory; techniques and dietary supplements for improving memory; and how memory is much more important than you think. Memory controls what you think about yourself and others and, subsequently, your full range of emotions.
Let us begin by considering different types of memory and the anatomy and chemistry of memory.
Categories of Memory
During our waking hours we are constantly scanning visually, and through our other senses of hearing, touch, smell and taste. We scan millions of bits of information per minute and a very small part of that information enters short-term memory. The capacity of short term memory is very small, only about seven bits of information. For example, if I were to read to you a series of digits and ask you to repeat them back to me from memory, you would have no problem until the series length reached about five digits, and then you would have to concentrate. You might then be able to repeat back a list of seven, but probably would have difficulty going much beyond that. I could train you to increase the size of each bit by linking together numbers but the capacity of short-term memory would still remain quite small and the time information can be held is very brief. For information to be remembered more than a few seconds, it must be transferred into long-term memory.
There is an intermediary memory system where we can hold information just long enough to complete a task, without transferring it into long-term memory. We refer to this as Working Memory. We must keep information in working memory in our consciousness, and we must continue rehearsing it. For example, if someone gives my wife directions to a gas station that include various right and left turns at various landmarks (I would not need such directions), she may be able to remember them just long enough to find the station, as long as she keeps repeating them to herself. As soon as she found the station, that information will be discarded, gone forever. Working memory would also be involved in remembering a phone number just long enough to dial it.
There are at least two different types of long-term memory: Declarative Memory, or memory for facts or past experiences in life, and Procedural Memory, which is memory for skills. The vast majority of what we think of as information in long-term memory is in declarative memory and here we generally make a distinction between semantic memory and episodic memory.
Episodic memories are tied to particular events, times and places. Episodic memories might include your recollection of meeting your husband or wife, bringing your newborn babies home from the hospital, or speeding along the highway with the car's top down on a warm spring day. By contrast, semantic memory is context free and represents your general knowledge about the world. Information stored in semantic memory may combine multiple episodic memories and other information that forms a clear definition of an object or concept. For example, your concept of "child" may be influenced by many personal experiences as a child, as the parent of a child and so on, but these memories are combined and together with other information form the general concept of "child" in semantic memory.
Procedural memory involves memory for riding a bicycle, swimming, playing chess or crocheting. Procedural memory is highly resistant to forgetting, as old maxims such as "never forgetting how to ride a bike" suggest. Dr. Daniel Schacter, a renowned psychologist at Harvard University, once took a patient with advanced Alzheimer's disease out on the golf course. Frederick was a life-long golfer and remembered all the proper procedures for teeing up the ball, choosing the appropriate club, swinging smoothly, marking his ball, and so on. He also had an excellent golf vocabulary, correctly using words such as "birdie" and "dogleg." However, at the end of each round, Frederick had no recollection of having played any holes, and when asked a week later to play again he responded by saying that he was a little nervous because he hadn't played in months.
Remote Memory is the repository for "unforgettable" experiences. These may be many decades old, going back to early childhood, such as my memory of the third grade and Sister Martha. My mother- in-law, Thelma Grant, who is eighty-eight years old, once demonstrated how effective remote memory can be even while much more recently learned information may be forgotten. She rummaged through a box of photographs that she hadn't seen in many years and found her junior high school graduation photograph. She then proceeded to name each of the fifty or so graduates and tell a detailed story about each. She then turned to my wife and said, "Well that was fun but I guess you and ... [long pause] ... what's-his-name will have to be leaving pretty soon."
Areas of the Brain Involved in Memory
The largest part of the brain is the cerebrum and it is divided into two halves, or hemispheres. The right hemisphere controls the left side of the body and the left hemisphere controls the right side. The hemispheres are connected at the corpus callosum, a band of some 300 million nerve fibers. There is some distinction between the hemispheres in right-handed people in that the left hemisphere is more closely associated with verbal/logical thought while the right hemisphere is associated more closely with visual and spatial tasks.
A one-eighth-inch thick, intricately folded layer of nerve cells covers the cerebrum and this is the cortex (Latin for bark). The cortex allows us to remember, to analyze and compare incoming information with stored information, to organize experiences, to learn languages, to make decisions and perform myriad other cognitive tasks.
It is not at all unusual for an individual to be talented when performing tasks controlled by one hemisphere of the cortex and normal, or even deficient in performing tasks controlled by the other. In that case, one is said to be right or left hemisphere dominant. I, for example, struggle with many mechanical and visual-spatial tasks and found engineering courses in high school and college very difficult, while English, history, economics, philosophy and psychology were quite interesting and easy to learn. Thus, I was left-hemisphere dominant, but that is certainly not the case in everyone. Many males and some females are right-hemisphere dominant and make talented mechanics and engineers, although they might struggle in writing a letter and never touch a crossword puzzle.
Knowing if one shows hemispheric dominance may be useful early in life. I once tested a young lady who was struggling in the eleventh grade of a Catholic school that would have been as alien as Mars to Sister Martha. This school, Archbishop Spaulding High School in Severn, Maryland, had given the young lady, Carol, every advantage possible. They gave her more time on tests than others, and when her test scores did not improve, they let her take open-book tests when everyone else was tested from memory. Finally, they let Carol take the tests home, along with her books and work on them there. Still, she struggled.
I saw Carol and her distraught mother and administered a number of tests, including a widely used intelligence test that has both verbal and "performance" subscales. The performance scales require that you manipulate objects, solve puzzles and so on. They are not dependent on verbal learning and memory. Consistent with her academic record, Carol scored far below normal on the verbal tasks and showed evidence of a profound verbal learning and memory disorder. However, she performed exceptionally well on the performance tests measuring visual spatial abilities. One test, for example, requires that red blocks painted diagonally white on some sides be arranged so as to form an overall design shown by the examiner drawn on a card. The designs get increasingly difficult and intricate as the test proceeds and most people fail well before the most difficult design is reached.
Carol completed all the exercises within the allotted time. This was one of eleven subscales in the most widely used intelligence scale of the time (it has been revised slightly since), so her performance was consistent on that scale with the highest IQ obtainable, even though she had performed on several verbal subscales at a level associated with a profound learning impairment. Her mother reported that Carol was the family "engineer," and was not only able to install all new electronic devices while barely consulting instructions, but could figure out any problem that arose on the family computer. Armed with this new knowledge, Carol's parents could plot her academic future. She would continue to struggle in high school, although we could restructure the way she attempted to memorize by using more visual than verbal techniques. She graduated (just barely) with her class. But then the world changed for Carol. She went off to a private two year school of design and specialized in computer graphics. She became the bright student helping others, a complete role reversal. Now, sixteen years later, Carol is a successful graphic designer living with her husband and children in New Hampshire.
The cortex of each hemisphere is divided into four areas referred to as lobes.
The lobes are specialized according to the type of information they store and process. For example, the largest of the four lobes, the frontal lobes, are associated with the performance of higher level cognitive functions including organization, planning, decision making and problem solving. Critical information related to these tasks is stored in the frontal lobes. The parietal lobes extend from the ear to the top of the head. They receive information from touch and are involved in the formation of some memories. The occipital lobes, located at the back of the head, are sometimes referred to as the visual cortex, and are responsible for visually mediated memory. The temporal lobes fit under the temporal bone above the ears and are involved with hearing, perception and, of particular importance, semantic memory.
Beneath the cortex is a group of cellular structures known as the limbic system. These structures, particularly the hypothalamus, control many basic body functions and also emotional responses. Several of these structures are of critical importance in memory. First is an area of the limbic system referred to as the hippocampus (pronounced as you would guess, hippo campus). Actually, there are two hippocampi, one in each hemisphere. This area has been very extensively investigated during the past several decades and is a structure shaped like a seahorse buried deep in the temporal lobes. (The word itself is Greek for seahorse.) These are critical structures in forming some new memories. For example, the hippocampus is very important in forming new episodic memories, but appears to play no role at all in procedural memories. The hippocampus is also involved in spatial or navigational memory.
Another limbic structure, also in the temporal lobes, just in front of the hippocampus, is an almond shaped structure labeled the amygdala (pronounced am ig du la). Like the hippocampus, the amygdala (Greek for almond) helps transfer information from short-term to long-term memory. Its main function seems to be that of linking memories that were formed through several senses. The amygdala also plays an important role in the formation and storage of memories with high emotional value. It is the amygdala that is responsible for indelible memories of events that may have occurred recently or many decades ago. The vivid image that is almost certainly in the minds of almost all Americans of where they were and what they were doing on the morning of September 11, 2001 is testimony to the power of the amygdala in what we remember.
A tragic case illustrates how delicate the interplay is among these memory structures. This is the well known case of HM, a twenty-seven-year-old man in 1953 suffering from intractable epileptic seizures. A Connecticut neurosurgeon, Dr William Scoville, in an attempt to halt or at least diminish the seizures, removed structures from the temporal lobes on both sides of HM's brain. He removed the hippocampus, the amygdala, and parts of some neighboring areas of temporal cortex. He had performed the first known bi-lateral, medial, temporal lobectomy. Immediately after the surgery, it was clear that it had produced profound memory problems. Although the seizures were reduced somewhat and HM could speak and converse normally, he had no idea where he was, to whom he was speaking, or what he had been doing five minutes earlier. HM's memory for events preceding the surgery remained largely intact, but his episodic and much of his semantic memory for events following the surgery was destroyed. He is still alive, but he can recall no one he has met and no experience he has had for more than a half century. HM lives truly alone.
Excerpted from THE MEMORY ADVANTAGE by THOMAS H. CROOK Copyright © 2007 by SelectBooks, Inc.. Excerpted by permission.
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