Optimizing Memory in the Adult Brain for Effectiveness in a Multitasking Society
"I am summoned to see the headmistress at morning break on Monday," said Miss Brodie. "I have no doubt Miss Mackay wishes to question my methods of instruction. It has happened before. It will happen again. Meanwhile, I follow my principles of education and give my best in my prime. The word ‘education' comes from the root e from ex , out, and duco , I lead. It means a leading out. To me education is a leading out of what is already there in the pupil's soul. To Miss Mackay it is a putting in of something that is not there, and that is not what I call education, I call it intrusion, from the Latin root prefix in meaning in and the stem trudo , I thrust. Miss Mackay's method is to thrust a lot of information into a pupil's head; mine is a leading out of knowledge, and that is true education as is proved by the root meaning. Now Miss Mackay has accused me of putting ideas into my girls' heads, but in fact that is her practice and mine is quite the opposite. Never let it be said that I put ideas into your heads.
In the passage quoted above from The Prime of Miss Jean Brodie , novelist Muriel Spark entertainingly and succinctly exemplifies the question educators, philosophers, and scientists have struggled with since the Golden Age of Greece: What does it mean to educate? In other words, how do we learn what we know?
This was once dangerous ground to tread on. In 399 BC when Socrates was asked why he was called “the wisest of all men,” he said it was because he knew that he knew nothing. His persistence in questioning the citizens of Athens to learn how they knew what they knew ultimately cost him his life. For eons each generation has asked the question. Yet it has never been completely answered. But thanks to modern technology, we may be getting closer.
So How Do We Know?
In the early part of the 20 th Century, human brains were thought to be storage facilities. Each brain cell would serve as a kind of bin where facts could be neatly deposited. The size of the brain was equated with the amount of storage space available for knowledge. It was known that injury, illness, or age could reduce the number of cells a person had, but it was thought that nothing could increase them. The assumption was that brain size had a direct correlation with one's ability to learn. From that assumption came two arguments:
• People are born with a given intelligence that sets limits on what they can learn
• Since men generally have larger brains than women, opportunities for acquiring greater knowledge would be wasted on most women
The rationale managed to keep many young women out of college and out of the professions for many decades.
When biologists started measuring non-human brains in an effort to categorize levels of intelligence among birds and beasts, they discovered that some creatures had brains that were noticeably larger than the largest human brain on record. A new way of measuring had to be devised. One attempted to establish a ratio between brain size and body size. On average, primates have brains that are 2.3 times larger than other mammals of the same body weight. Although humans and chimpanzees have similar weights, our brains are 3 times larger than theirs. Among non-primates, porpoises and dolphins have brain-body ratios equal to or greater than ours. Animal rights activists sometimes use these numbers to argue the superiority of dolphin intelligence.
The idea that smart people must have more brain cells (a.k.a. “gray matter”) persisted until Albert Einstein's brain was made available for study by a select group of neuroscientists. More than 25 years after Einstein's death in 1955, microscopic examination revealed that his brain wasn't composed of more gray matter but more “white matter.” White matter refers to myelin, a protein substance that forms around the thread-like projections that connect neurons to each other. Myelin serves as an insulation that allows electrical impulses to flow faster between brain cells. Einstein's neurons had more and stronger connections with each other. This revelation led to a new understanding of how brains function.
Advances in technology have allowed brains to be explored on two fronts:
• Regional—via PET scan, MRI, EEG, etc.
• Cellular—via electron microscope
Scanning mechanisms enable on-line, real time observation of brains in action—in other words, responding to specific stimuli. Although the technology cannot pinpoint individual neurons, it does demonstrate the complex interaction of different areas within the brain—such as amygdala, hippocampus, parietal lobes, temporal lobes, etc. Moreover, it shows that some of these areas can shift and change over time and with experience. The electron microscope reveals where these changes start.
One out of ten brain cells are neurons. They are the only cells in our bodies that are known to communicate directly with one another. This isn't because the other cells are antisocial. They just lack the means to do so. Neurons are structurally different. In addition to the cell body, they have special appendages (nerve fibers) that literally reach out to touch other neurons—sometimes close neighbors, sometimes cells several feet away which is more impressive when you learn that 70,000 brain cells can fit on the head of a pin. Nerve fibers come in two varieties: axons and dendrites. Axons provide output—i.e. they transmit. Although they are usually in contact with dendrites, they can also connect with cell bodies and other axons. Dendrites receive input, usually from axons, but sometimes they “talk” to other dendrites.
Generally, neurons have one axon, but an axon can have multiple branches enabling it to transmit to many cells at once. A neuron will usually have many dendrites, and the dendrites have many spines (little knob-like projections) that axons can connect to. All of this was unknown before the development of the electron microscope which enables scientists to peer into the vast universe of the very small.
You Must Remember This
At any given moment billions of messages are being exchanged via electro-chemical activity within our brains. Most are involved with maintenance or survival—such as regulating heartbeat, monitoring temperature, sensing movement, etc. Unless there is a sudden or extreme change, we remain blissfully unconscious of these goings-on. Just because we're unconscious of them doesn't mean we have no memory of them.
There is increasing evidence to suggest that memories aren't stored in individual neurons, but in the way the neurons are connected to each other. Some neurons are part of vast networks or systems; others only have small, regional connections. Some connections are well insulated and will last a lifetime; others are more fragile than soap bubbles. They exist for a fraction of a second before dissipating. Sometimes breaks occur within a system or between systems, due to injury or illness. Disconnections result in the loss of functions—such as a stroke that renders an arm useless or a tumor that disrupts the ability to link faces with names. Victims of such tragedies often suffer the frustration of knowing what to do but not being able to remember how to do it.
In theory, memories are reconstructions of the past. In fact, memories are thoroughfares by which we travel through time. The memory of our species is embedded in our DNA and passed along via egg and sperm to the future. Personal memories are woven throughout our brains, altered and adjusted with each new experience, making our brains as individual as our fingerprints.
Different types of memories form in different parts of the brain. The amygdala, an almond-shaped structure deep inside the temporal lobe, is fully formed and functioning at birth. Fears take root here that may later germinate as phobias and flashbacks, the unspeakable memories of things to avoid.
Nestled up against the amygdala, looking more like a paw than the seahorse for which it was named, the hippocampus lays down new memories, establishes personal history, and creates spatial awareness. The hippocampus is connected to almost every part of the neocortex, the thin outer layer of the brain where self-awareness, language, and abstract thought take form. An event does not become a long-term memory until it's bounced back and forth between hippocampus and cortex for two or three years. Much of the activity takes place during sleep and in dreams. After that, the frontal and temporal cortices can recall information without the aid of external stimuli.
Non-personal memories such as the capital of Vermont , the multiplication tables, or the location of the spare car key also begin in the hippocampus and end in the cortex. How quickly we can retrieve the information is dependent on how often we need to remember it and its emotional value. This is why cramming all night for a final can net a decent score on a test although the hastily acquired knowledge is forgotten soon afterwards. It is also why immersion into a culture is the quickest way to learn a second language. By involving all the senses—sight, sound, taste, smell, touch, and movement—vast networks of related information can be constructed in a short time. The process of becoming an expert requires a similar immersion.
Development of expertise in any subject requires time and opportunity. But exposure to information, no matter how intense, is not enough . For information to be of use, it has to be linked to an objective and a procedure for achieving that objective. Thoughts turn into actions when nerve impulses activate muscles in an organized manner. Without synchronization, muscle movement is reduced to tics and twitches. We would not be able to walk, talk, chew, write a check, kiss a loved one, smile, scream, juggle, cook—in short do anything but vegetate.
Movement is initially organized in the cerebellum, the “little brain” in the back of the skull. The evolution of the cerebellum is linked to the need to stabilized vision while the body is in motion, adjusting the rate and degree of eye movement to that of head movement. Otherwise, the world would seem like it was made with a hand-held video camera.
Coordination takes practice. Watch a baby learning to roll over, learning to crawl, learning to walk, learning to talk. It all takes a lot of practice. And then suddenly, it happens and it seems as if one has always known how to do these things. At this point control shifts from the cerebellum to the putamen, a part of the basal ganglia that sits atop the brain stem. Activities learned through repetition become automatic here. We don't have to think about the process anymore. Muscle memory takes over. Actions flow smoothly, one after another. Choices are made swiftly and executed masterfully. Some activities, like walking in one's sleep, can even be performed unconsciously.
How Knowledge Is Made
Most of the memory discussed thus far can be categorized as “long-term.” It is part and parcel of who we think we are and what we habitually do. In short, we owe our self-knowledge to long-term memory. Certainly some of it is genetic, lending a distinctly human quality to our lives. Animals such as chimpanzees and gorillas, with whom we share a great percentage of DNA, exhibit more “human-like” behaviors than do dogs, parakeets, or houseflies despite the fact that we have more experience with pets and pests than we do with apes. But we are also molded by experience. Physically, we may very well be a reflection of what we eat. Mentally, we become what we think.
What we think is a turbulent, ever-changing blend of past, present, and future prepared in a cauldron called “working memory.” More than just a short-term or temporary storage facility, working memory is the means by which past experiences are combined with present events to produce future effects. It is where knowledge is processed through planning, problem solving, and decision-making. We employ our working memories when we compare prices at the supermarket, carry on a conversation, solve crossword puzzles, balance check books, find our way home from a party, compose music, write novels, design nuclear reactors, etc.
All mammals have frontal lobes whose primary task is to control movement. In humans the frontal lobes occupy one-third of the brain. From there, in the prefrontal cortex, the working memory works its miracles. The prefrontal cortex is a convergence zone where electro-chemical messages sent from systems throughout the brain meet, greet, and are sent on their way back into the brain to change it. Here emotions, sensations, conditioned responses, and motivations blend. Some of these blends will be weak and erratic and quickly forgotten; others will be strong enough or frequent enough to forge new connections between neurons. In this way knowledge is built upon what we already know. This is why it is easiest to learn something new when we can associate it with something familiar.
Sometimes new experiences can challenge or disrupt old patterns of behavior. Then we feel confused. Uncertainty can generate hyper-awareness and large muscle paralysis. The discomfort is a sign that our working memory is seeking more information from various systems and inhibiting impulsive action until an appropriate response is determined. If we can tolerate the discomfort, we will be rewarded with a new insight and awareness that we've been forever changed. In other words, we'll have been educated.
Education is the result of a leading out of what is already there (i.e. long-term memories) and a thrusting in of new experiences, ideas, sensations, and/or feelings. Education enriches our lives by enriching our brains with neural connections. We can know and know that we know because of a wonderful system called working memory. Like all brain systems, working memory improves most with intentional use—for instance by playing games, solving puzzles, and socializing. In the process we learn both how to absorb knowledge and how to create it.
© Copyright 2004 Donalee Markus, Ph.D. & Associates