If an alien life form were to look at a human brain, it might dismiss it as so much useless tissue, simply there as filler. But the unimpressive appearance of a human brain belies its myriad of remarkable abilities. The brain is the “grand central station” of the body. Every second of every day, and in less than the blink of an eye, the brain constantly analyzes information, monitors changes, and issues instructions to keep us running smoothly from the day we’re born. It stores our memories, processes new information, enables us to seamlessly move through our day, and allows us to make decisions about the world as we experience it. Even after an injury it is still at the helm, allowing our body to continue as it should.
So, how does the brain carry out this impressive array of activities? You might not think it, but at this point, there is still a lot we don’t know about the brain. For example, until just over a decade ago, scientists believed that brain cells could not regenerate. However, in 1999, Princeton scientists showed that neurogenisis is, in fact, taking place; that new neurons are continually added to three areas of the most complex region of the brain, the cerebral cortex, in adult monkeys. This finding suggests entirely new ways of explaining how the mind accomplishes its basic functions, from problem solving to learning and memory, and could eventually lead to new methods for treating brain diseases and injuries. 1
One thing we do know for sure is that our organic supercomputer’s communication system is made up of chemical-electrical impulses that fly between approximately 100 billion neurons using neurotransmitters such as dopamine, serotonin, and noradrenalin. The end result of the presence of these neurotransmitters is our ability to remember things, change our mood, and pay more attention to what we’re doing. And, as Batman had Robin, and the Lone Ranger had Tonto, no one cell can do all this alone without a sidekick. Working hand in hand with these highly developed 100 billion neurons are trillions of “support” cells, called glia. Structurally resembling neurons, glia cells are not able to transmit nerve impulses but simply support, insulate, and protect their more delicate partners.
Read on in this chapter to find out more about the anatomy and physiology of the brain, specialized brain functions, conditions and diseases of the brain associated with advanced age, and how to best maintain your brain in tiptop condition in your later years.
The Stuff That Brains Are Made Of
Nowhere else in the body can you find the same proportion or complexity of nervous tissue that is the brain. It has been mapped out into four major regions; the cerebral hemispheres (left and right), diencephalon, cerebellum, and brain stem. Each cerebral hemisphere is divided into four lobes, named for the cranial bones that lie over them; the frontal, parietal, occipital, and temporal. A fifth lobe, the limbic lobe, is situated deeper inside the brain.
The Cerebral Hemispheres
The cerebral hemispheres are larger than they look. In fact, they are folded over onto themselves and if unfolded would be about the size of a hub cap or extra large pizza. Each hemisphere takes care of one side of the body but it’s not what you think. The right hemisphere takes care of the left side of the body and the left takes care of the right. Housed inside the hemispheres are some very important lobes.
The Lobes of the Brain
As the name suggests, the frontal lobes are located in the front portion of the cerebral hemispheres and are responsible for planning and reasoning, adjusting your mood and emotions, and the makeup of your personality. Voluntary movements are initiated from the frontal lobes. A small, but very important, part of your left frontal lobe converts thoughts into words. The rear portions of the cerebral hemispheres house the parietal lobes which are responsible for sensory perceptions such as touch, taste, temperature and pain. They also take in auditory and visual signals. These signals are then linked to memories that correspond with the information in new the signals, giving these new signals meaning, association, and sense.
|Much of the effect of classical music would be lost without the involvement of your temporal lobes. These lobes interpret the many frequencies of sounds and volume. They also help you understand the meaning of the lyrics of a song (although some lyrics are beyond comprehension!). Your temporal lobes also commit things to memory and let you recall those memories; the right temporal being more involved with memories of things you will have seen and the left being more involved with things you will have heard. The function of the occipital lobes can easily be remembered because these lobes decode visual input. They analyze forms, colors, and movement and associate them with stored memories to allow you to recognize and identify objects such as the large, red truck moving at a high speed toward you.|
|The limbic lobes, or cingulated gyri, are involved in adjusting things like blood pressure, heart rate, pupil size, and other responses associated with a mind/body link during an emotional response such as when you’re scared, angry, or stressed. In order for the brain to know what’s going on in the rest of the body, it relies on the peripheral nervous system to relay messages and information to the spinal column and then on up into the brain. Once the brain has the information it needs, it then issues commands based on this information back out into all parts of the body via this same peripheral nervous system. The only exception here is the facial nerves which enter and exit the brain directly through the skull.|
How the Message Is Relayed
Now that we understand the composite parts of the brain, let’s take a look at how they all work together. This is actually accomplished by two distinctive parts; the hard-wired neurons and the free-floating soup of chemical messengers. Although many different types of cells make up the nervous system, the primary functional unit is a cell called the neuron.
Much like a hockey stick or golf club, every neuron has two distinct ends, each with its own purpose. One end of a neuron is structured to receive chemical messages while the other end is structured to transmit. The receivers are called dendritesand the transmitters are called axons. Axon lengths alternate between being very short or very long depending on where the neuron is located. At the heart of the neuron is the nucleus which manufactures most of what the neuron needs to survive and function.
Although close, neurons never actually touch each other. A chemical messenger, or neurotransmitter, has to cross a small space between neurons in order to keep the information flowing. This space is called a synapse. Tiny sacs in the end of the axon launch neurotransmitters into the synapse. These neurotransmitters then cross the synapse and attach to receptors on the neighbouring cell. Not all neurotransmitters carry the same message. Different neurotransmitters are deployed depending on the intent of the message. For example, acetylcholine is considered an excitatory neurotransmitter. It is used when the message being sent is meant to bring about a response such as a muscle contraction or when it’s time for a gland to secrete a hormone. GABA, serotonin, and dopamine are all inhibitory neurotransmitters, meant to slow or contain responses.
What were we talking about? Oh right, memory.
Memory isn’t just about where you left your car keys, but so much more. Our memories provide us with information about who we are, where we are, if we’re safe, which actions to take, and that we do, in fact, like gingerbread when we smell it baking. Memory is what allows you to recognize people and surroundings. It lets you recognize the past and make decisions about how the future should be shaped. Unfortunately, memory can’t be discussed in the same terms as a kidney. It’s not a body part we can replace when it wears out. Instead, it’s a brain-wide process that is not centered in one particular place or another.
Do you remember what Aunt Agatha gave you for Christmas last year? The reason you can remember that stunning crocheted doily is because of an incredibly complex series of events that took place in your brain from the moment you read the “From” notation on the tag to when you actually held it in your hands. This series of events developed a memory from a collection of information gathered from your senses (visual, touch, auditory), which was interpreted and stored for later recollection. When you think about the doily, the brain retrieves all the information it needs to reform the image in your mind; its shape, function, sound, color, and name. With this information, the entire image of the doily is reconstructed by the brain. Scientists are still working out the finite details as to how and where, exactly, we organize, store, and recall aspects of our life that we call “memories”. What the experts are sure of, at this point, is that memory follows a three-step process; encoding, storage, and retrieval.
Encoding begins with the senses. This influx of information is used to form the basis of a memory. When you got your first puppy, you committed to memory the color of its eyes, the smell of its fur, and how soft it was. You probably remember what its little puppy teeth felt like when it bit down on your finger and what its first bark sounded like. All this sensory information, sound, smell, touch, sight, were important facts that travelled from your sensory organs to your hippocampus, that part of your brain responsible for compiling all these sensations into one single experience. Along with your frontal cortex, your hippocampus analyzes this input and stores it in different parts of the brain. That much we know, however to date, the scientific community is still trying to piece together how all these different bits of sensory input are then brought back together when you want to recall the memory of your first puppy.
Memory and Learning
We’ve already talked about how brain cells communicate with one another via axons, synapses, and dendrites. However, connections between brain cells aren’t set in concrete — they change all the time. Brain cells work together in a network, organizing themselves into groups that specialize in different kinds of information processing. As one brain cell sends signals to another, the synapse between the two gets stronger. The more signals sent between them, the stronger the connection grows. Thus, with each new experience, your brain slightly rewires its physical structure. In fact, how you use your brain helps determine how your brain is organized. It is this flexibility, which scientists call plasticity, which can help your brain rewire itself if it is ever damaged. The brain organizes and reorganizes itself in response to your experiences, forming memories triggered by the effects of outside input prompted by experience, education, or training. 2
Storage: Short-Term and Long-Term Memory
Not everything we see is committed to memory. Your brain filters out the unnecessary and makes a determination as to whether something should be committed to your limited-capacity short-term or long-term memory based on your perception of, and how much attention you’re devoting to, an event. For instance, a flower you saw and liked may be committed to short-term memory but the feeling of touching a hot stove is definitely committed to long-term memory to keep you for repeating the act in the future. Events that become familiar and recognizable, or acts undertaken repetitively, are more likely to be committed to long-term memory as you can easily associate a new experience with a stored memory about the same experience. For instance, the more you water ski, the more likely you are to remember what you did the last time out. So when seniors are involved in the same task/event/experience again and again, they commit it to memory that much easier.
Retrieval A memory is retrieved automatically with little to no input from you. All your mind has to do is “request” it. If you have a hard time remembering things, it’s not that you have a “bad” memory, it’s more likely that it’s just one part of the process that isn’t working properly, not the whole system. So what does this mean?
To review, in order to commit something to memory, first you must be aware of, and pay attention to, what you’re doing. If you pay attention, the information will be retained and you’ll be able to retrieve it later on. If you can’t retrieve a memory, one of these steps is faulty; either you didn’t pay enough attention to what you were doing, information wasn’t retained properly, or the retrieval process is defective. And as we age, these steps become more vulnerable to breakdown.
Physical Changes Work Against You
Researchers have their theories about why our memory declines as our age increases. To date, the most popular train of thought seems to be that, as we age, fewer and fewer cells are available in a small area of the frontal lobe to produce the neurotransmitter acetylcholine which is vital to learning and memory. Aging also takes its toll on the hippocampus which loses five percent of its nerve cells every ten years. By the time you’re an octogenarian, you’ve lost twenty percent of your original nerve cells. In addition, genetics, environmental toxins, smoking, and alcohol all contribute to memory decline.
The good news is that studies suggest that, to a certain extent, stimulating the brain can stop cell loss and actually increase brain size. The point that needs to be made here is that even if you can’t remember as well in your 80’s as you could in your 20’s, you shouldn’t stop trying. It may take a bit more effort, but it’s worth it in the long run.
COGNITIVE SKILLS AND ABILITIES
The word cognition means “the act or process of knowing”. Reasoning, awareness, perception, knowledge, intuition, and judgment are all aspects of cognition. One uses one’s cognitive abilities to make sense of the information the senses send to the brain every minute of every day and to recall things from memory. Cognitive abilities allow us to carry on a sensible conversation, tune in to our environment, ponder new information, draw associations, and learn new skills. Conversely, cognitive impairment is defined as the difficulty in dealing with, or reacting to, new or novel information or situations.
Causes of Cognitive Decline
As we age, it is natural to experience a progressive drop in overall cognitive ability. This is exhibited by a decline in the efficiency of the short-term memory, an inability to embrace abstract thinking like we used to, or to learn as quickly as we used to. Physiological damage that can lead to cognitive decline can include free radical damage to the brain, a decline in key hormones, diminished oxygenation of the brain, effects of prescription drugs, infections, allergies, and changes in lifestyle, diet, and nutrient absorption.
Taking it one step further, dementia is a collective term used to denote a deterioration of intellectual faculties, such as memory, cognition, and concentration. Alzheimer’s is the most common disease associated with dementia. A decline in cognitive ability does not automatically signal the onset of dementia or diseases such as Parkinson’s and multiple sclerosis which can also cause mental slowing with anxiety or depression. In dementia-causing illnesses such as Alzheimer’s, the decline continually worsens until normal daily activities become severely impaired. Always talk with your primary health care professional if you’re unsure about whether symptoms are due to the normal course of aging, stress, fatigue, or due to another cause altogether.
Cognitive functioning can also be affected in seniors who may become socially isolated for a variety of reasons, including medical conditions, loss of a loved one, depression, loss of mobility, and living considerable distances from family and friends. According to a University of Michigan study, published in the February 2008 issue of the Personality and Social Psychology Bulletin, psychologists Oscar Ybarra, Eugene Burnstein and Piotr Winkielman from the University of California, San Diego noted that “the higher the level of participants’ social interaction, the better their cognitive functioning.” 4 These psychologists also reached the conclusion that “social interaction directly affects memory and mental performance in a positive way.”
Loss of cognitive abilities should not be thought of as an automatic function of aging. Some seniors never show any signs of cognitive decline while others will experience a loss of skills and abilities to varying degrees. If you want to keep those synapses firing in rapid succession, you have to keep exercising your brain in much the same way you would your body.
Whether you get together with friends once a week to play cards, do word or number puzzles, quilt, lawn bowl, golf, go ballroom dancing, volunteer at your local school, teach a craft, or anything else which requires concentration, you’re doing your brain a favor by keeping it active, and by extension, young. Keeping your mind sharp may even reduce the risk or delay the onset of age-related dementia.
Any game that requires you to think two steps ahead is a great choice. Some examples include dominoes, backgammon, checkers or chess, card games, bingo, scrabble, jigsaw puzzles, crosswords, word searches and Sudoku.
Curiosity Didn’t Kill The Cat, It Made Him Sharper
Mental activity exercises the brain and keeps it fit, challenging you to use all your faculties so you can stay in the game. Try and find new interests that put your current skill levels to the test; learn another language, try new dance steps, or acquire a new hobby (photography, scrapbooking, drawing, music). When you take part in new activities, it stimulates brain cells and flexes your reasoning skills, memory, and processing speed.
Socializing Is Good For Your Brain
Do you remember the last time you were introduced to someone new? Did you remember their name the next time you met? Being out and about in social situations is a great way to challenge your memory and attention to detail. Joining a new organization, attending evening adult education courses, and volunteering are all great ways to use educational opportunities as brain training. Being a new member of a group generally requires learning more about their history, activities, mission and vision. When you have to commit all this to memory in order to become an effective member of the group, your brain gets a great workout.
Nutrition is important for your whole body but even more so for the brain. We’ve already looked at how memory, attention and mood are all functions of the brain however, what hasn’t been discussed yet is that all three, and more, can be affected by your nutritional choices and a lack of key nutrients that help boost your cerebral stamina. It’s important to remember that it’s not about one food or another, but the combinations that you choose. Eating a variety of foods every day helps you cover all the bases but, if you’re interested in specifics, the following nutrients play an important role in brain health.
Omega-3 Fatty Acids
According to Dr. Carol Greenwood, a senior scientist at Baycrest’s Kunin-Lunenfeld Applied Research Unit (KLARU) and professor of nutritional sciences at the University of Toronto, “A good diet consists of a blend of healthy components since you want to support the brain’s pathways with more than one nutrient.” Omega-3’s have also been linked to nerve cell regeneration. Fish oils, which are the active form of omega-3 fatty acids, are a key element in our brain cells and also help decrease inflammation which can be harmful to the brain. You can find these oils in fatty fish such as salmon, tuna, mackerel, anchovies, and sardines.
Antioxidants help boost brain health and longevity, and help to eliminate harmful compounds like free radicals which can damage brain cells through oxidative stress. Getting a good variety of antioxidants is as simple as remembering to “eat a rainbow every day”. Fruits and vegetables such as blueberries and broccoli are a gold mine, as are red and green peppers and carrots. Switching out a few cups of coffee a day for green tea can also make a difference. Unfermented green tea, such as Oolong, is loaded with catechins, a subgroup of polyphenols which fight free radical damage in the body. Blackberries, raspberries, cherries, raisins, red wine, and rhubarb are also good choices but the clear winner in the catechin category is dark chocolate.
B Is for Brain Food
All B vitamins are brain food and an overall nourishing tonic for the entire nervous system. Signals sent between nerve cells in a busy, hungry brain are dependent on vitamin B because the family of B vitamins helps form many of the neurotransmitters used in the brain. Pyridoxal phosphate, a B6 member, is pivotal in the synthesis of the neurotransmitters serotonin, dopamine and GABA. When thiamine (B1) is too low, the levels of the neurotransmitters glutamate (important for neural communication, memory and learning) and aspartate (another major excitatory transmitter; excitatory neurotransmitters increase the likelihood that the nerve cell will fire) drop off as well. Foods containing B vitamins are everywhere; dark green leafy vegetables contain B vitamins as does asparagus, beans, eggs, potatoes, whole grains and peanut butter.
Iron Hemoglobin, an iron-containing protein, is responsible for the transport of the bulk of the oxygen in our blood throughout the body, including the brain. Our reasoning skills, working memory and ability to pay attention and learn are significantly affected by a lack of iron. The better sources of iron are found in animal products but iron can also be found in foods such as spinach, blackstrap molasses, lentils, broccoli and Brussels sprouts. Consider taking a vitamin C supplement as vitamin C helps increase iron absorption in the body.
Vitamin E also helps with the transport of oxygen to the brain and a deficiency may result in damage to red blood cells (which carry hemoglobin) and destruction of nerves. Vitamin E protects brain cells from free radical damage and helps to keep your mind sharp. Signs of a vitamin E deficiency can include impaired balance and coordination. Good sources of vitamin E include spinach, broccoli, sunflower seeds, almonds, olives, avocados and whole grains.
Hydration and the Brain
We all know that dehydration can lead to feelings of nausea, heart palpitations, light-headedness, and/or weakness. But by the time dehydration has reached the brain, the problems really set in. A lack of fluids, such as water, leads to an improper balance of minerals in the bloodstream. This imbalance throws the normal function of brain cells into chaos, and if left untreated, can lead to their destruction. Maintaining the right balance of water and minerals in brain cells is absolutely essential. Once dehydration has gone beyond the limits of just the body and on to the brain, symptoms will include physical lethargy, mental fatigue, memory problems and confusion. The solution is simple; make sure at least eight glasses of water per day are consumed.
Dementia is a general term that refers to a variety of brain disorders. Physical changes in the brain cause dementia. Alzheimer’s disease (AD) is the most common form of dementia. AD is a degenerative disease that destroys brains cells. Currently AD accounts for 64% of all dementias in Canada. AD is not part of normal aging, and currently, we do not yet know what causes AD however researchers have identified risk factors associated with it including advanced age, genetics, pre-existing diseases, infections, environmental toxins, alcohol and tobacco use, diet and exercise. AD typically follows certain stages that cause changes in the person’s and family’s lives. As AD progresses, it affects different areas of the brain and symptoms can become more severe. In most cases, the disease progresses slowly and the symptoms of each stage may overlap however AD affects each individual differently. The duration of the disease is usually seven to ten years but can be much longer in some people. 5
A stroke is the rapid loss of brain function due to a disturbance in the blood supply to the brain.6 This disturbance could manifest in the form of a blood clot or hemorrhage. The result is the inability of the brain to function which can cause loss of movement, an inability to comprehend or formulate speech, and/or a loss of sight. Whatever the symptoms, a stroke is a medical emergency and should be treated as such. Call 9-1-1 immediately if you suspect someone is having a stroke. The quicker the patient receives medical attention, the higher the chances of a full recovery.
A simple way to remember the important symptoms of a stroke is by using the acronym F.A.S.T.; Face, Arms, Speech, Time.
- FACE: Ask the person to smile; check to see if one side of the face droops.
- ARMS: Ask the person to raise both arms and watch to see if one arm drifts downward.
- SPEECH: Ask the person to repeat a simple sentence and listen for slurred words or an inability to form a sentence that makes any sense at all.
- TIME: Time is of the essence; get medical help as soon as possible.
|The carotid arteries stem off of the aorta (the primary artery leading from the heart) and lead up through the neck, around the windpipe, and on into the brain. When TIAs or stroke occur from blockage in the carotid artery, which they often do, symptoms may occur in either the retina of the eye or the cerebral hemisphere (the large top part of the brain).Symptoms include the following:
||The other major site of trouble, the basilar artery, is formed at the base of the skull from the vertebral arteries, which run up along the spine and join at the back of the head. When stroke or TIAs occur here, both hemispheres of the brain may be affected so that symptoms occur on both sides of the body. The following symptoms may develop:
|Speed of Symptom Onset: The speed of symptom onset of a major ischemic stroke may indicate its source:
From Stroke, The New York Times, August 28, 2012.
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