2/12: Understanding the Brain

Welcome to Week 3 of our Introduction to Brain Fitness Class!

This week we start a spectacular journey--one where we will learn about and try to understand the human brain. Understanding our brain, even at a basic level, can go a long way toward helping us make better lifestyle choices that will contribute to better brain health, as well as a better quality of life. This lesson will introduce you to our amazing brains--we’ve lived with them all our lives, but most of us don’t know much about them at all! We will learn what our brains are made up of, how they function, and how we can change and improve them by making simple, healthy, lifestyle choices.

See this week's lesson below. If you prefer, you can download and print the lesson in handout form. Additional handouts are available at the end of the lesson. If you would like to review the PowerPoint presentations that summarize this week's topics, you can find them here: Overview of the Brain; Neurotransmitters & Neuromodulators; Brain Plasticity; and Lifestyle for a Healthy Brain. After you complete the lesson, find out how much you have learned by taking this short quiz. And don't forget to check out the Student Spotlight of long-time brain fitness student Kathy Lasky.

What the Brain is Made Up Of

Neuroscience has progressed far from the days when the brain was considered “cranial stuffing,” and when the heart was considered to be the “seat of intelligence” (Wikipedia, n.d.). Though this view was eventually reversed, we still use language today that refers to that ancient belief (e.g. “memorizing something by heart”). Modern science has a much better understanding of the brain and how it works. Let’s take a look at the basics of our wonderful brains.

Cerebrum

The word “cerebrum” is Latin for “brain.” It designates the largest part of the brain—the entire top surface—consisting of gray matter and white matter. The cerebral cortex is the outer surface, or gray matter. The cerebrum consists of two cerebral hemispheres, divided by a longitudinal fissure (down the middle from the front of your head to the back). The halves are linked by the corpus callosum (a bundle of neural fibers), which passes messages between the two hemispheres. The right hemisphere controls the left side of the body, and the left hemisphere controls the right side of the body. The functions of the cerebrum include reasoning, planning, memory, and sensory integration.

Lobes

The cerebral cortex, the outer surface or gray matter of the brain, is divided into four lobes, which perform different tasks, but work together:

Frontal: thinking, problem solving, voluntary movement, personality, memory
Parietal: sensation & feeling (touch), language
Occipital: visual processing
Temporal: auditory processing, learning, and feelings

There are also more than 100 different functional cortical zones (called “cortical fields”), each accounting for different aspects of perception, memory, thinking, emotion, or action control.

Cerebellum

The cerebellum, located in the back of the skull, is responsible for muscular activity, including balance and coordination. However, new research suggests that the cerebellum also plays a critical role in every aspect of higher brain functions, including attention, thinking, planning, and decision-making (Bhandari, 2018).

Brain Stem

The brain stem connects the brain to the spinal cord, and is responsible for automatic functions like breathing, heart rate, and temperature.

Limbic System

The Limbic system, the part of the brain responsible for basic emotions and drives, spans both hemispheres of the brain. It contains parts of the frontal, parietal, and temporal lobes. Among the very important structures found within the Limbic system are the amygdala, an almond-shaped structure, which is involved with the experiencing of emotions; and the hippocampus, a seahorse-shaped structure that is key to learning and memory consolidation.

Watch this short video that explains the important structures found within the Limbic system. We will talk about several of these throughout the semester (2 minutes).

Blood Supply

The blood supply to the brain is critical, as it carries nutrients and oxygen to feed the brain. The brain uses about 20% of the oxygen we breath in, so when our cardiovascular system is compromised, the vitality of our brain can also be compromised. The brain receives blood from two sources: the internal carotid arteries, which run up the left and right sides of the neck, and the vertebral arteries, which run up the back of the neck. Blood delivers oxygen and nourishment to the brain through a system of blood vessels that reach every part of the brain. It is an elaborate protective system, different from the other parts of our body, which prevents unwanted molecules from entering.

Listen to this short video for a visual explanation of how nutrients are carried to the brain and how the blood-brain barrier protects it.

Neurons

Our brains are comprised of brain cells, also called “nerve cells” or “neurons.” It is estimated there are 100 billion neurons in the human brain. A neuron consists of the nucleus (soma), dendrites (which receive electrical signals), an axon (through which electrical signals travel), and axon terminals (which transmit the electrical signal from one neuron to another). The axon is wrapped with a myelin sheath that helps speed the transmission of electrical impulses as they travel toward the axon terminals.

The brain also contains specialized neurons called glial cells, the most abundant cell type in the central nervous system. Glial cells come in many varieties, including oligodendrocytes, astrocytes, ependymal cells, Schwann cells, microglia, and satellite cells. Glial cells are responsible for providing support to neurons, such as pruning unused neurons and providing insulation to axons.

Communication Between Neurons

Communication between our vast network of brain cells is accomplished by brain chemicals called neurotransmitters and neuromodulators. A neurotransmitter is a brain chemical that is responsible for the transmission of electrical signals (messages) from one neuron to another. When an electrical signal travels through an axon to an axon terminal, an impulse is generated, resulting in the release of neurotransmitters into the synaptic gap--the narrow gap, or synapse, between neurons. There are roughly between 1,000 and 10,000 synapses terminating on each neuron. Estimates of the numbers of these synapses in the mature human brain range between about 60 trillion to about 240 trillion. After being released into the synaptic gap, the neurotransmitter is then taken up by receptors on a neighboring dendrite, and the signal continues through that neuron to the next. The neurotransmitter is then reabsorbed into the originating axon terminal--this is called "reuptake." Some neurotransmitters are lost and do not get reabsorbed.

Scientists have managed to identify over 100 neurotransmitters in the human brain, but evidence suggests we have significantly more than this number (wiseGEEK, n.d.). Scientists also believe that only about 10 of these brain chemicals do 99% of the work of the brain (King, 2013).

Neuromodulators

Neuromodulators are chemical messengers that are released from a neuron that affect not just a single neighboring neuron, but groups of neurons. They are not reabsorbed or broken down, as neurotransmitters are, so they can produce long-lasting effects. Neuromodulators are released when something happens that signals the brain that the event should be stored and remembered.

Read more about neurotransmitters and neuromodulators in the Companion Guide on p. 14.

Grey Matter & White Matter

You have probably heard our brain referred to as “grey matter.” But what does that really mean? Grey matter is the darker tissue of the brain (pinkish-grey), consisting mainly of nerve cell bodies (neurons) and branching dendrites. White matter is made of dense bundles of axons connecting different parts of grey matter to each other (the axons get their whitish appearance as they are covered in myelin, which is white). If we added up the lengths of all the axons interconnecting the neurons in just the forebrain of a young adult, they could easily extend to the moon and back!

Here is an easy way to remember the difference between grey matter and white matter:

Grey matter = cell bodies

White matter = networks

How Aging Affects the Production of Brain Chemicals

As we age, the brain’s production of neurotransmitters drops. As it’s ability to encode input deteriorates, the brain slows down its pace. That is why it may take you longer to decide what you are seeing or hearing, or make it more difficult to keep up with conversations or events going on around you. In response to this, Posit Science, the creator of Brain Fitness, has created brain-training exercises that stimulate key brain processes, which in turn stimulate your brain to produce more neurotransmitters and neuromodulators. The increased production of these brain chemicals enhances both your cognitive abilities and your memory. The exercises target the root causes of cognitive difficulties so you can see positive changes in your brain.

Brain Chemicals and Mental Disorders

Impairment or abnormalities in the production of neurotransmitters and neuromodulators has been found to play a role in many mental disorders, including the following:

Schizophrenia is caused by an impairment of dopamine-containing neurons; medications that block dopamine receptors help to alleviate symptoms.
Depression may be caused by abnormal signals--the flow of serotonin is defective and may not make it to the receptor sites. Prescription medicine blocks the reabsorption of serotonin and allows it more time in the synapse before it binds to the receptor.
Alzheimer’s disease is affected by a loss of cells that secrete acetylcholine in the basal forebrain—the part of the brain responsible for sensory and associative information processing and motor activities.
Anxiety disorder may be influenced by neuromodulatory systems, including norepinephrine and serotonin imbalances.
Attention Deficit Hyperactivity Disorder (ADHD) may be the result of imbalances in dopamine and norepinephrine in the brain.

Ways to Detect & Measure Brain Activity

Modern medical technology has given us a new frontier—what happens inside our brain. There are many methods used today to measure brain activity and detect which areas of the brain are stimulated under certain conditions or during specific activities. These brain scans can reveal the following:

Parts of the brain that are activated during certain functions
Brain activities related to specific thoughts, sensations, and movement
Pathologies (like a tumor)
Mood disorders

Let’s look at a few of the technologies available today:

EEG (electroencephalogram) scans measure electrochemical pulses in the brain.

fMRI (functional magnetic resonance imaging) and PET (positron emission tomography) scans measure blood flow, using electromagnetic activity and water molecules.

CT (computed tomography) scans builds pictures based on X-rays.

Brain Plasticity

Brain plasticity, also called neuroplasticity, is the notion that the brain can be shaped by our experience; in other words, the brain has the ability to change at any age. Up until the last few decades, it was thought that the brain was only “plastic” (changeable) during childhood; after that, it became “hard-wired” and was incapable of change. This was the prevailing belief when Dr. Michael Merzenich, scientist and co-founder of Posit Science, began his research in the late 1960s. One of the pioneers in the field of neuroscience, Dr. Merzenich showed that the adult brain is indeed capable of change, and that by changing the input the brain receives, it dramatically changes the organization of the brain! The development of a healthy and highly functional brain is a consequence of how a person has used it. Every person has the capacity to control positive, plastic brain change.

Through experimentation, Dr. Merzenich found that with each newly learned skill, brain connections are remodeled—nerve cells form connections and create new neuronal pathways. The machinery of the brain becomes customized for that skill. When we master a new skill, connections between our neurons are enhanced and strengthened. There can be hundreds of millions or even billions of synapses altered as we work to become specialized in a particular skill. Like a map, your brain can change and acquire more and more detail as you learn and challenge it.

Read more about brain plasticity in the Companion Guide, pp. 8-10.

Neurogenesis

The creation and development of new neurons in the adult brain—called neurogenesis—is a hot topic right now in the field of neuroscience. Though we now know that neurogenesis is possible, even in the adult brain, understanding how it happens is still a work-in-progress. It is widely accepted that adult neurogenesis occurs in two main areas in the adult brain: the hippocampus and the olfactory bulb (Gage, 2002; McPherson, n.d.). Adult neurogenesis might occur in other regions, but this is not yet well established.

Watch this excellent video clip (2 minutes) that explains how neuroplasticity works.

Negative Plasticity

Not all changes in the brain are positive. Negative plasticity means the brain is changing, but not for the better. Synaptic connections between neurons are temporary and their strength is highly modifiable (plastic). Synapses eventually wear out and are subject to a slow, ongoing biological replacement. They can easily be driven by experience or learning to strengthen and multiply, or be weakened and die off. Posit Science notes four factors that may contribute to cognitive decline, or negative plasticity. They are:

Brain disuse: Most of us have heard the term, “Use it or lose it.” When we live a sedentary lifestyle and don’t exercise our brains, we can lose brain volume.
Noisy processing: This means that the input of what we hear, see, smell, taste, and feel degrades as our peripheral sensory organs don’t function as well as they used to.
Weakened neuromodulatory control: We tend to produce fewer brain chemicals (neurotransmitters and neuromodulators) as we age due to disuse and noisy processing.
Negative learning: This is when we adapt a behavior to make up for the above three factors. For instance, if you forget how to do a simple math calculation, you use a calculator instead of practicing the forgotten skill.

Your brain registers negative messaging. Dr. Merzenich teaches that it is tremendously destructive to tell yourself “you can’t,” if, in fact, succeeding requires just a little more serious effort and practice on your part. When you tell your brain “I can’t” often enough, it becomes a self-fulfilling prophecy. Consider those things you might be doing that might accelerate this backward change; you may be surprised to find you have adopted some destructive, compensatory habits that encourage negative plasticity. In the next section, we discuss how negative plasticity can be countered.

Lifestyle for a Healthy Brain

As you learn more about your brain and ways you can make it healthier through the lessons, lectures, and experiences in this course, you may be starting to realize that the way you have been operating in life may not be optimal from a brain health perspective. You may be at a point where you stop and ask yourself the following questions:

How could you reorganize your everyday life in ways that assure brain health improvements?
How can you organize your life in ways that will not merely sustain—but also grow--both your competencies and the person you are?
What could you do to help assure that the person you are continues to flourish, grow, and thrive?

Of course, the decision to make healthier lifestyle choices is up to each one of us. Some things tend to motivate us highly, and we are driven to take action, while other things don’t. Why is this? A research team in China may have come closer to pinpointing where motivation resides in the brain. A 2017 research study successfully identified neurons important for the drive to win—in mice (Nemo, 2017). In the study, an isolated group of neurons in the dorsomedial prefrontal cortex played a critical role in mice’s persistent behavior. When the researchers fired up these neurons using light, the mice were motivated to win competitions in which they had previously lacked the will to succeed. Could this be true in the human brain? We’ll have to wait for further research before we can be sure. Until then, we need to find ways to motivate ourselves to make healthier lifestyle choices—we know ourselves best and therefore know what will work.

A [now] 82-year-old grandfather from China, Wang Deshun, is an example of someone focused on keeping his body healthy, his brain fit, his mind sharp, and his attitude fearless. For his 80^th birthday, he enjoyed techno music and went parachuting. Deshun’s philosophy is to always dare to try something he’s never done before. A few of his philosophies about living a healthy lifestyle are: 1) Keep learning and exercising; 2) Find a diet that works; 3) Have a goal; and 4) Try new things (Pawlowski, 2016).

Watch this very inspiring video clip (just under 2 minutes) and meet this remarkable octogenarian. Get ready to be inspired!

This video (6 minutes) talks about various things you can do to improve your brain—essentially, healthy lifestyle choices you can make.

Posit Science: Four Essential Pillars of Brain Health

Posit Science, the company who created Brain Fitness, believes that in order to have a healthy brain, we need to live a healthy lifestyle. In other words, simply doing brain exercises alone, though valuable, is not enough. There is no single intervention (brain exercises, physical exercises, etc.) that will work for all of us. In order to optimize our outcomes (better brain health, better physical health, fulfillment in life, etc.), we need to take an individual, well-rounded approach. Posit Science has summarized a substantial amount of research into four areas that are essential to good brain health—they call these the Four Pillars of Brain Health.

These pillars are:

Physical Exercise
Mental Exercise
Good Nutrition
Stress Management

The four pillars of brain health, along with other factors (socialization, sleep, etc.), should add power to the brain machinery that controls your brightness and pleasure. As your faculties improve, so will your self-satisfaction and confidence. We will learn more about each of these pillars during the semester and find out why they are so critical to our brain health. But let’s take a brief look at each one.

Physical Exercise

Physical exercise, particularly aerobic exercise, is one of the most important things you can do for yourself and for your brain. Aerobic exercise raises the heart rate in a healthy way, conditions the heart muscle, and delivers more oxygen to the brain. Whatever type of physical exercise you choose to do—do something. But start out by talking with your doctor, especially if you are not currently physically active or have health concerns. Pick a physical activity that you would enjoy, and set an achievable goal for how much you exercise. Schedule it into your daily routine until it becomes a habit.

Mental Exercise

Challenging your brain is key to keeping it healthy and preserving cognitive function. Giving yourself daily challenges that require close, serious, and highly attentive engagement at a level where you are continuously challenged yields amazing results. So be curious! Sign up for classes, attend lectures, study a new language, learn a musical instrument, focus on conversations and learn to listen, talk with someone every day about something that really matters to you, put learning on a schedule and take it seriously.

Good Nutrition

Good nutrition is as important to your body and brain as good fuel is to your car. If you constantly filled your car’s gas tank with a poor grade of fuel, and never changed the oil, your car would eventually cease to function. So it is with the body. We need good nutrition in order to give our bodies what they need to function at their best, to process energy, and to keep our immune systems strong. Plan meals around vegetables, adding fruit, protein, dairy, and grains. Be sure to eat a variety of fresh and unprocessed foods, particularly leafy greens. And remember that it is also important to eat correct portions (for most of us, that would mean downsizing our portions!).

Stress Management

Stress is a brain cell killer! When we are under constant, chronic stress, our brains are flooded with cortisol, the body’s main stress hormone. We feel less able to think clearly and make decisions. We may experience depression, and isolate ourselves from friends and loved ones. Chronic stress can be devastating to a healthy brain, and that is why Posit Science included it as one of the four essential pillars of brain health. In order to manage extreme stress, be sure to get regular cardiovascular exercise and adequate sleep. Reconnect with family and friends; practice meditation, yoga, mindfulness, or another calming activity. And don’t forget to take some time every day for yourself just to breath deeply and recharge.

Your Work and Challenge

Now that we have learned a little about how complex, remarkable, and responsive our brains are to change, perhaps you can give serious thought to what your job is in all of this. Let’s outline some of the many things you can start doing:

Work actively to grow your neurological resources
Refocus and re-intensify how you listen and hear, see, and feel; pay attention to your senses
Re-engage with life with vigor, seriousness, and challenge
Nurture behaviors that are demanding on every level of perception and cognition
Learn to learn again
Celebrate every small step in progress
Avoid the effortless path; stop gong to such great efforts not to engage in real life!
Grow in your everyday activities by improving old abilities and developing new ones, by leading a life more richly supplied with interesting experiences, and by adopting a positive attitude and reclaiming your thirst for joy in life

As your brain gets healthier, that health will be manifested to a very significant extent by a greater capacity for having fun and enjoying life.

Conclusion

We’ve had a look at what makes up our remarkable brains, and learned that we have the power to shape and reshape them by the things we do and think. Just the knowledge that our brains are plastic (changeable), should empower and invigorate us to live a healthier lifestyle, one that will ensure the healthiest brain we can have. Remember, whatever sustains your brain, sustains you!

Additional Resources: Handouts

Works Cited

Bhandari, Tamara. (October 25, 2018). Mind’s quality control center found in long-ignored brain area. Science Daily. [Online article]. Washington University School of Medicine. Retrieved from: https://www.sciencedaily.com/releases/2018/10/181025142018.htm

Burns, M. (n.d.). Introduction to the brain. [PowerPoint]. Available through the Brain Fitness Basics course.

Gage, F. H. (2002). Neurogenesis in the adult brain. Journal of Neuroscience, Vol. 22(3), 612-613.

King, P. (Apr. 2, 2013). How many types of neurotransmitters are there in a human brain? Quora [Website blog]. Retrieved from: https://www.quora.com/How-many-types-of-neurotransmitters-are-there-in-a-human-brain

McPherson, F. (n.d.). Adult neurogenesis. About Memory [Website]. Retrieved from: http://www.memory-key.com/memory/neurogenesis

Merzenich, M. (2013). Soft-wired: How the new science of rain plasticity can change your life (2nd ed.). San Francisco, CA: Parnassus Publishing, LLC.

Nemo, L. (July 13, 2017). Pinpointing the brain’s motivation switch. Scientific American [Online article]. Retrieved from: https://www.scientificamerican.com/article/pinpointing-the-brain-rsquo-s-motivation-switch/

Pawlowski, A. (Nov. 4, 2016). At 80, ‘China’s hottest grandpa’ says there’s 1 way to tell if you’re old or not. Today [Online article]. Retrieved from: https://www.today.com/health/80-model-wang-deshun-china-s-hottest-grandpa-t104699

Wikipedia. (n.d.). History of neuroscience. Retrieved from: https://en.wikipedia.org/wiki/History_of_neuroscience

wiseGEEK. (n.d.). How many neurotransmitters are there? [Website]. Retrieved from: https://www.wisegeek.com/how-many-neurotransmitters-are-there.htm