This is A Brief Educational Summary of Neuroscience 101, Part Two. It is for informational purposes only. For medical advice or diagnosis, consult your physician. Ask your doctor how often he or she exercises.
Part One of LOVE YOUR BRAIN emphasized the importance of the circulation of oxygen and nutrient-rich blood supply to the brain through the carotid arteries located on each side of your neck and through the vertebral arteries located through each side of your vertebrae that form the bony protection of your spinal cord.
Those making an A in this course will recall that the brain’s dependence on a healthy circulation requires a smooth lining of the blood vessels’ intima, or innermost lining. If brain blood supply is blocked by an embolism or clot, you will experience a “stroke.” Strokes can also be caused by a hemorrhage into the brain. If brain blood supply becomes slowly diminished over months to years, vascular dementia may occur.
Death occurs within six minutes if brain blood supply is terminated, as in drowning, obstruction of the airway, cardiac arrest, significant blood loss, or injury to the respiratory center located in the brain. Victims of near-drowning may survive longer than six minutes if the water is cold and the subject is youthful or healthy.
Part Two of our neuroscience series is concerned with the neuron, the unique cells that form the brain, and its fundamental operational part. But bear in mind the brain has many functioning parts, all working in unison, much like a well-rehearsed top-notch symphony orchestra.
Adding to the brain’s complexity, revealing its “Intelligent Design(er) known by people of faith as God, we are merely naming and describing what gives rise to the human mind, the soul, and to consciousness itself.
STOP! Before acclaimed “scientists” leave these pages unread, proudly disgusted with any attempt, no matter how minimal, to blend faith with science, need I remind you that our most respected early scientists were devout Christians, and some had biblical names?
Need I also remind you that the “null hypothesis” itself is first and foremost a form of pragmatic faith, and much about what is “known” in Neuroscience is based entirely on believing without seeing.
Psychopharmacological medications for depression and psychosis, for example, were based on empirical data and theoretical assumptions about the human synapse (discussed below) for many years before a human synapse was actually visualized by means of advanced brain imaging and computational skills were developed.
Athletic participation and physical exercise have appealed to me all my life. With close friends, we played football, basketball, and baseball in the Community League. Several of us played high school football. I felt better after a workout. The good feeling lasted at least several hours, independent of whether our team won or lost. Exercise had a specific dose-response curve.
Like everyone else, I had my share of “the common miseries of life,” neglected exercise, ate until I was full, and kept eating. For a decade, I went from job to job, took graduate courses in the evening, tried to be a good husband and good father to our 4 children, God’s irreplaceable gifts.
I was 32, in the second year of medical school, studying Pathology, when I was sent to observe an autopsy or postmortem examination. Three young adults killed in a car accident were being examined.
“These young men already had serious evidence of lifestyle diseases. Look at their coronary arteries. The cholesterol plaques lining their intima were nearly closing the main blood supply in the heart. What caused this pathology?”
None of them said anything. It was 1964.
“Gentlemen, had they survived the car crash, I doubt these young men would live to be 50. Their sedentary life or lack of exercise and a fatty diet would have killed them.” It was a sobering, scary wake-up call.
I found the Royal Canadian Air Force Physical Fitness Manual, worked out every morning before class, and strictly followed a healthy diet. Slowly, 25 pounds were lost happily, and the sense of well-being I knew as an athlete returned. It was a real, lasting physical and psychological phenomenon known to every person who discovered physical and mental fitness.
“What I feel now is just too real to be in my head,” I thought. Somehow, I knew its cause could be found. With evidence that could be replicated, more people would be willing to make the effort to become and remain fit throughout their lifespan. It became an objective, in addition to other objectives of my life. Eventually, fitness influenced my psychiatric practice, my University teaching, and my daily life.
Critics said, “everybody knows that exercise makes you feel good, but it is largely due to the ‘shower effect.’ It’s a nice warm shower after your workout, not the exercise, that helps you feel good.” I never believed this explanation.
Dr. Fred Goodwin, National Institute of Health, agreed to study urine samples of students who exercised regularly. An upward trend of a specific central neurotransmitter metabolite (discussed below) was found in the urine specimens.
When I heard of Fred Gage’s research on the effects of exercise on the human brain, I knew he was revealing the truth, the very link I “knew” existed.
In 1998, Fred Gage of the Salk Institute conducted research on neurogenesis (the growth of new neurons). Dr. Gage reported that brain-derived neurotrophic factor (BDNF) serves an important role in converting brain stem cells into neurons, a complex process often requiring a cocktail of factors.
Gage’s research has shown the following:
BDNF is a supporting factor in neurogenesis: BDNF promotes the proliferation and differentiation of neural stem/progenitor cells (NSCs) into neurons, but is not the sole factor.
Gage’s discovery of adult neurogenesis: Fred Gage is widely known for demonstrating that new neurons are generated in the adult human brain, challenging a long-held scientific dogma.
Environmental enrichment and EXERCISE promote neurogenesis: Gage lab found that environmental enrichment and physical exercise enhance the brain’s ability to generate new neurons.
Using stem cells to model disease: Gage used human stem cells to model neurological and psychiatric diseases in the lab. For instance, they have shown that neurons generated from the skin cells of people with schizophrenia are dysfunctional.
What is unique about a neuron or brain cell?
Neurons are specialized cells with a unique structure that includes a cell body, dendrites, and an axon. Their electrical excitability enables rapid, precise communication throughout the body.
Unique structural characteristics
The unique morphology of neurons is directly related to their function as communication messengers.
Axons: A neuron usually has a single axon that carries signals from the cell body to distant areas, enabling communication throughout the body.
Dendrites: Branch-like extensions on neurons receive signals from other neurons. Each neuron’s dendritic tree lets it process thousands of messages at once.
Synapses: Neurons connect with other cells at synapses, where axon terminals release neurotransmitters. Most involve chemical signals; some use electrical connections.
The adult human brain has about 86 billion neurons and 100 to 500 trillion synaptic connections, forming a vast network for complex information processing. The brain contains about 86 billion neurons—similar to the estimated 100–400 billion stars in the Milky Way—but its roughly 500 trillion synapses vastly outnumber the stars.
Synapses: Connections between neurons that transmit signals
The language of neuroscience need not be daunting. Grasp this concept to be well on your way to mastering the most basic functional process in the brain:
The presynaptic neuron’s axon carries the essential message (signal) to the synapse, or space. To cross the synapse of space, a neurotransmitter is released. The message may be a pleasant memory. The postsynaptic neuron’s dendrite receives the message. There are a number of neurotransmitters, each needed to deliver a message or signal.
You may have heard one explanation of clinical depression as a “chemical imbalance.” The above paragraph explains how many antidepressant medications work. Depressed people have difficulty recalling pleasant memories. The correct antidepressant may return the recollection of pleasant memories.
I review ten cases of depression treated principally with exercise in my book, Healing Depression by Degrees of Fitness, Robert S. Brown and Cristy Phillips, 2019.
In five decades of psychiatric practice, I have never treated a physically fit depressed person.
Cognitive Behavioral Therapy is effective in the treatment of depression without the use of medication.
Unique functional characteristics of Neurons:
Electrical and chemical signaling: Neurons communicate by generating action potentials that travel along their axons, converting electrical signals into chemical ones at synapses through neurotransmitter release.
Excitability: Neurons are electrically excitable and alter their resting potential when stimulated, enabling them to process and transmit information.
Long-term survival without division: Most mature neurons do not divide, so they persist for a lifetime and are not replaced if lost. Unlike skin or blood cells—which frequently renew—neurogenesis only occurs in certain brain areas.
High metabolic rate: Neurons consume large amounts of glucose and oxygen to function, making them highly sensitive to oxygen loss.
Neurons vs glial cells
Glial cells are non-neuronal cells that support and protect neurons in the nervous system. Beyond acting as “nerve glue,” they regulate neural communication, maintain brain homeostasis, and remove debris. They exist in both the central nervous system (CNS) and the peripheral nervous system (PNS), with various types present in each.
Glial cells are far more numerous than neurons. There are several distinct forms of glial cells, one of which forms the myelin sheath around axons in the CNS, which insulates them and allows for faster nerve impulse conduction.
Glial cell dysfunction is associated with neurological disorders, especially neurodegenerative and demyelinating diseases. Glial cells may lose their supportive functions or harm neurons and myelin directly.
Neurodegenerative diseases
Alzheimer’s disease (AD): Glial cells play a key role in AD neuroinflammation, which is linked to amyloid plaque and tau tangle formation.
Amyotrophic lateral sclerosis (ALS): Glial dysfunction contributes to motor neuron degeneration in ALS.
Huntington’s disease (HD): The genetic mutation that causes HD impairs the function of glial cells, leading to inflammation and neuronal death.
Demyelinating diseases
Multiple sclerosis (MS): An autoimmune disease where glial cells contribute to both myelin sheath destruction and repair in the central nervous system.
Progressive multifocal leukoencephalopathy (PML): This rare demyelinating disease is caused by the JC virus, named for John Cunningham. It infects oligodendrocytes (glial cells). Most people acquire the JC virus in childhood and carry it harmlessly in tissues like the kidneys and bone marrow. It remains dormant without symptoms in healthy individuals. Nonetheless, the virus may be reactivated in individuals with compromised immune systems, resulting in the onset of progressive multifocal leukoencephalopathy (PML), a rare and potentially fatal neurological condition.
Psychiatric and neurodevelopmental disorders
Schizophrenia: Schizophrenia is associated with microglial dysfunction and disrupted glial-neuronal interactions.
Autism spectrum disorder (ASD): Microglial dysfunction in synaptic pruning is linked to neurodevelopmental deficits in ASD.
Epilepsy: Astrocyte (glial cell) dysfunction can affect neurotransmitter and ion balance, which may result in increased neuronal excitability and seizures.
Ischemic injury (stroke): Glial cells influence post-stroke inflammation, with effects that can either protect or harm tissue.
Glial cells play a critical role in the pathogenesis of gliomas, which represent the most prevalent form of malignant brain tumors, acting as the primary cellular origin of these neoplasms.
Microglia in psychiatric disorders: Microglial dysfunction contributes to psychiatric disorders such as schizophrenia and autism by affecting synaptic pruning, causing chronic neuroinflammation, and disrupting neuronal circuitry.
Glial cell dysfunction and metabolic issues are associated with depression, affecting glutamate metabolism, neurotransmitters, and neuronal energy. Studies show fewer and smaller astrocytes (glial cells) in people with major depressive disorder.
Neurotransmitter dysregulation
Astrocytes, a type of glial cell, are involved in the regulation of key neurotransmitter levels in the brain. If astrocytes do not function properly, this balance may be disrupted.
Neuroinflammation
Chronic stress and inflammation are closely tied to depression, with astrocytes playing a central role in neuroinflammation.
Impaired synaptic plasticity and connectivity
Astrocytes are key parts of the tripartite synapse and crucial for synaptic plasticity—the brain’s capacity to adjust its connections.
Our third and last article on Love Your Brain will examine the meaning of the gray and white matter of the brain, the largest part of the brain (Cerebral Cortex), and our brain when we sleep.
Love Your Brain enough to:
Improve your brain function
Stay physically active:
Regular exercise increases blood flow to the brain, which can improve cognitive function and memory. And exercise does much more.
Prioritize sleep:
Restorative sleep is crucial for brain health, just as it is for any other organ.
Keep learning:
Challenge your brain. Learning new skills, reading books, or engaging in mentally stimulating hobbies can help build new neural connections.
Reduce stress:
High stress levels can negatively impact brain function. Breathing exercises can help, but here is an important role of Spiritual Fitness.
Eat a well-balanced diet:
A nutritious diet is essential for maintaining brain health and function.
Challenge your brain
Break routines:
Small changes, such as choosing a new commute or eating with your non-dominant hand, challenge your brain in fresh ways.
Stay social:
Engaging in social activities keeps your brain active and can improve cognitive function. Take an online course. Join a Zoom Bible Class. I can highly recommend the two I attend weekly from my studies.
Be creative:
Creative activities can help you think in new and flexible ways. I tried painting with watercolors and failed miserably. I write poetry and make believe it’s good.
Try new things:
Actively seek out new experiences to push your brain outside of its comfort zone and encourage growth. I went on a mission trip to Greece, fearful until I got to the Greek Bible Institute, and then it was rewarding.
The next time exercise is discussed at a dinner party with friends, try not being rude. Simply clear your throat and say, “All this talk about endorphins that make you feel good when you exercise is hogwash! Give runners injections of endorphin-blocking agents after a race, and they still feel happy. Tell me about BDNF (Brain Derived Neurotrophic Factor) after exercise, and I will listen! Let us cheer Dr. Fred Gage.
Robert S. Brown, MD, PHD a retired Psychiatrist, Col (Ret) U.S. Army Medical Corps devoted the last decade of his career to treating soldiers at Fort Lee redeploying from combat. He was a Clinical Professor of Psychiatry and Professor of Education at UVA. His renowned Mental Health course taught the value of exercise for a sound mind.
