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BRAIN AND SLEEP
"All my life I have focused on being healthy, but I wanted to learn more about slowing the aging process. Your regimen is effective because I continually receive statements like: 'You look fantastic! What do you do to keep looking so young?' I know for a fact that people think I am considerably younger than my chronological age." SANDY (55), NASHVILLE, TENNESSEE
Part I of this book describes the Problem--the fact that we are genetically programmed to age, to enjoy optimal health for a relatively short period of time, and then are forced to spend much of the rest of our lives dealing with the effects of aging, a process that has as its sole purpose the destruction of our health and our ultimate demise. Before we begin our discussion of the various processes associated with aging, it is important to realize that growing older (and wiser!) is not the same thing as aging. Everyone grows older all the time, but we aren't necessarily aging as we do so since, by definition, the aging process is one of deterioration.
You grew older today, but did you age as well? If you drank a few cups of green tea, had five servings of fruits and vegetables, exercised for at least 30 minutes at your target heart rate, took nutritional supplements optimized for your age and health situation, spent quality time with close friends and loved ones, consumed a glass of red wine, had a romantic (and sensual!) time with your spouse or significant other, and got 8 hours of quality sleep, then you probably aged very little if at all. If you were a coach potato, ate doughnuts for breakfast, skipped lunch, consumed an excessive amount of coffee, smoked cigarettes, and got into stressful arguments with friends, co-workers, and loved ones, then you probably aged a lot. People can look old in their thirties or young in their sixties, and the lifestyle choices you make every hour make all the difference.
Multiple processes cause us to age. Some are simple, such as the depletion of a vital substance called phosphatidylcholine in our cell membranes (which you can reverse by supplementing with that substance as we discuss below). Some are complex, such as keeping your most important organ--your brain--healthy. In this chapter, we'll discuss optimal brain health along with sleep since sleep is so vital to brain function. Then we'll move down to the heart, the digestive tract, and the sexual organs and hormones. We'll complete our overview of how the body works with a discussion of various metabolic processes, including inflammation, methylation, and glycation, and finally look at genomics, the new field that is unlocking the secrets of our genes, which control and regulate all bodily functions.
WE THINK, THEREFORE WE ARE
Your brain makes up only 2 percent of your weight yet receives 20 percent of the blood coming from the heart and uses 20 percent of your body's oxygen and glucose. It also represents 50 percent of your genetic complexity. In other words, half of your genes describe the design of your brain, with the other half describing the organization of the other 98 percent of your body. Moreover, your brain is the master puppeteer: It controls every beat of your heart, every blink of your eyes, the release of your hormones, not to mention all of your willful activities. It has long been regarded as the seat of consciousness, the true you. So it makes sense to consider what you can do to keep it healthy--and happy, too! As it turns out, there is a lot you can do. The ideas in this chapter can dramatically slow down brain aging and help you avoid the often catastrophic downsides of brain dysfunction.
Intelligence is arguably the most important phenomenon in the world because intelligence allows us to understand and shape our environments. The best example we have of an intelligent entity is the human brain itself. And the secret of its design is not hidden from us. Although there's a skull around it, we can see inside a living brain with increasingly precise scanning technologies. This is a wonderful example of Ray's law of accelerating returns: The spatial resolution of brain scanning is doubling every year, and the amount of data we are gathering on the brain is also doubling every year.
We now know the human brain is composed of about 100 billion neurons plus a trillion glial support cells. It was originally thought that the glial cells just provided physical support for the neurons, but recent studies have demonstrated that they play a role in influencing the synapses, which are the connections between neurons. We have about 100 trillion such connections, and that is indeed where most of the action takes place. So there is a lot of complexity.
We are gathering an exponentially expanding mountain of data on the brain, but can we understand it? A controversy going back thousands of years to the days of Plato is whether we are intelligent enough to understand our own intelligence. Computer scientist Douglas Hofstadter wrote that "it could be simply an accident of fate that our brains are too weak to understand themselves." Since Hofstadter wrote that line in 1979, we have shown that this is not the case. As we gather enough data on specific brain regions, we have been able to model these areas in precise, mathematical terms and actually simulate them on computers. For example, computer scientist Lloyd Watts and his colleagues have created a computer simulation of a dozen regions of the auditory cortex, the regions of the brain responsible for processing sound from the ears. Applying sophisticated psychoacoustic tests to Watts's simulation produces results very similar to applying these tests to human auditory perception. At MIT, there is a similar model and simulation of the visual cortex, which processes visual information.
At the University of Texas, there is a simulation of the cerebellum, an important region that makes up more than half of the brain's neurons and is responsible for skill formation, for example, catching a fly ball. We have always wondered how a 10-year-old accomplishes this feat. All she has to do is solve a dozen simultaneous differential equations in a few seconds, but most 10-year-olds have not yet taken calculus. We now understand how this works. Those equations are indeed solved by her cerebellum using a mathematical technique called basis functions. It takes place, of course, without conscious awareness, and we do have to train the cerebellum to learn specific tasks, which is why practicing a skill is important. Again, a variety of tests on this computer simulation of the cerebellum provides results similar to human skill formation using our biological cerebellum. This illustrates the oft-stated insight that although the brain is capable of some remarkable accomplishments, we perform these feats without much understanding of how our brains actually carry out these missions.
An ambitious project is underway at IBM to simulate the cerebral cortex, arguably the most important region of the brain and the one responsible for our abstract reasoning. As of the writing of this book, this simulation has successfully undergone its first set of tests.
As we continue the accelerating progress toward "reverse-engineering," understanding the methods of how the brain works, we'll gain far greater insight into our own human nature, which has been the goal of the arts and science since we first wrote symbols on stone tablets over 5,000 years ago. The results of this grand engineering project, which now includes over 50,000 scientists and engineers, will also provide us with methods for ever more intelligent computer software. But the benefit most relevant to this book is that we will gain far more powerful ways of fixing what goes wrong in our brains.
And there is a lot that does go wrong. As we pointed out before, evolution focused on our formative years and enough of our early adulthood to allow us to raise our children so that they became self-sufficient. As a result, keeping our brains healthy much past our twenties was not a trait selected by natural selection when our brains evolved. Our brains are subject to either sudden or gradual decline with age, to self-destructive addictive behaviors, to depression and anxiety disorders, and to many other limitations, not to mention potentially catastrophic lapses of judgment.
YOU CREATE YOUR BRAIN
Perhaps the most important insight relevant to brain health that has come from recent advances in information technology is the plasticity of the brain. Since the mid-19th century, it was thought that brain regions were hardwired for specific tasks and that neurons could not be replaced. In 1857, French neurosurgeon Paul Broca related specific cognitive deficits to particular regions of the brain affected by injury or surgery. For more than a century, it was believed that unlike other areas of the body that are capable of repairing themselves, the brain could not replace its neurons and connections that had been lost or damaged and that we are continually and irretrievably losing brain matter.
From recent brain imaging research, we now know the brain possesses plasticity, meaning it is perhaps the most dynamic and self-organizing organ of the body. Although there is some degree of specialization in the skills of different regions of the brain, stroke victims are often able to transfer skills from a damaged region to one that is undamaged. Moreover, we can see in recent brain scans how we actually grow new brain connections and even create new neurons from stem cells as a result of our thoughts.
In an experiment with monkeys at the University of California, brain scans obtained before and after the animals were trained to perform a specific task involving the nimbleness of one finger showed substantial growth in neural connections associated with controlling that finger. An experiment with humans who were taught how to play the violin showed substantial growth of connections associated with the fingers of the left hand responsible for controlling the notes. A brain scanning experiment at Rutgers and Stanford universities involved training dyslexic (reading- impaired) students how to distinguish between hard-to-resolve consonants such as "p" and "b." After the training, brain scans showed substantial growth and increased activity in the region of the brain responsible for this discrimination. Paula Tallal, one of the scientists who created this dyslexic training system, commented that "you create your brain from the input you get."
In the latest brain image studies, we can see real-time movies of individual interneuronal connections actually creating new synapses (connection points between neurons), so we can see our brain create our thoughts and in turn see our thoughts create our brain.
The true meaning of Descartes' famous dictum, "I think therefore I am," has been debated for centuries, but these findings provide a new interpretation: I do indeed create my mind from my own thoughts.
IN VIVO IMAGES OF NEURAL DENDRITES SHOWING SPINE AND SYNAPSE FORMATION
The lesson of these new insights is that our brain is entirely like any of our physical muscles: Use it or lose it. We all know what happens to your muscles if you are bedridden from illness or just living the couch potato life. The same thing happens to your brain. By failing to engage it in intellectually challenging activities, your brain will fail to grow new connections, and it will indeed become disorganized and ultimately dysfunctional. The converse is also true for both body and brain. If someone who has not been physically active for a sustained period starts a program of physical therapy and regular exercise, she can regain her muscle mass and tone within a matter of months. The same thing is true of your brain.
Many studies demonstrate that people who maintain their intellectual activities throughout life remain mentally sharp. A Canadian study called the Victoria Longitudinal Study has shown that older individuals who routinely engage in mentally challenging activities, including everyday activities such as reading, remain mentally alert, as compared with the substantial cognitive decline of those who do not engage in these activities.
Just as we have more than one muscle to keep fit, we have more than one region of the brain that we need to exercise. To keep the cerebellum--the region of the brain that controls voluntary movement--healthy, you should engage in physical activities, particularly those that involve the development of skills such as sports.
The concept that certain brain activities occur in the left half of the brain and others on the right is only partially true. A recently discovered type of neuron called the spindle cell crosses from one side of the brain to the other and appears to be heavily involved in higher-level emotions. In recent brain scanning experiments using new types of scanners that can image individual neurons, these cells "light up" (become especially active) when test subjects are shown a picture of a loved one or hear their child crying. The spindle cells are unusual in that they can be very long, spanning the entire length of the brain, and are deeply interconnected with other neurons. One spindle cell will typically have hundreds of thousands of connections to other cells. Unlike the highly organized cells of the cerebral cortex, the brain region responsible for rational thought, the spindle cells display unpredictable and fairly exotic structures and connection patterns.
They are connected to almost every other region, so they receive input from everything else going on in our brain. From these studies, it is apparent that the spindle cells are not doing rational problem solving, which is why we don't have rational control over our emotional responses.
Although each spindle cell is very complex, we don't have very many of them. Only about 80,000 of our 10 billion neurons are spindle cells. Only a few animal species have spindle cells at all. Gorillas have about 16,000, bonobos about 2,100, and chimpanzees about 1,800. Recently we have discovered that whales actually have more than humans. Interestingly, newborn humans don't have any spindle cells. They begin to appear at about 4 months and develop through 3 years of age, which exactly mirrors the ability of young children to deal with higher-level emotions and moral issues.
About 45,000 of the spindle cells are in the right hemisphere, and 35,000 are in the left. This small imbalance appears to account for the notion that the right brain is the emotional brain and the left brain is the more rational brain. Although the right brain does have more spindle cells, both halves of the brain are engaged in logical and emotional activities. Individuals with a rare disorder who use only half of their brain often appear to behave almost normally, engaging in both logical and emotional activities.
EXERCISING YOUR MIND