Our Anatomy Sets the Limits for Our Behavior

OUR ANATOMY SETS THE LIMITS FOR OUR BEHAVIOR

This excerpt from Peter Bevelin’s Seeking Wisdom introduces the biological basis of behavior. Its historical cases and study descriptions reflect the book’s account.

To understand the way we think and why we make misjudgments, we must first determine what influences our behavior.

Why can't we fly?

To do what we do today demands the proper anatomical foundation. To fly we need wings. To walk we need legs, to see we need eyes, and to think we need a brain. Our anatomy, physiology and biochemistry are the fundamental bases for our behavior.

If we change anatomy, we change behavior. A bird’s wings need the muscles and skeletal support that make flight possible. Speech likewise depends on anatomy and neural control; the position of speech organs is only part of the explanation for differences between humans and other apes.

Another example on how a change in anatomy changes behavior comes from the Neurosciences Institute in California. In one experiment, scientists took a small portion of developing brain tissue from a quail and put it into the same spot of a chicken embryo. When the chick hatched, it had both quail and chicken nerve cells. Depending on what cells were transplanted, the results were either a chicken that crowed like a quail or a chicken that bobbed its head like a quail.

Damage to the prefrontal cortex, behind the forehead, can affect impulse control, planning, and social behavior. The effects depend on the location and extent of the injury; violence is not an inevitable result. A classic example is that of railway construction foreman Phineas Gage. In 1848, he was victim of an explosion that drove an iron rod through the frontal region of his brain, damaging his prefrontal cortex. Before the accident he was considered stable, dependable, industrious, and friendly. Historical accounts describe changes in Gage’s personality and behavior after the accident, including impulsiveness and unreliability. These reports illustrate the possible effects of injury, rather than a complete account of his later life.

Other studies show that damage to the amygdala- a region of the brain, linked with emotional states and social behavior - reduces the tendency to feel and respond to fear. Stimulating the amygdala can elicit intense emotional reactions. In 1966, Charles Whitman killed 14 people and wounded 38 from the clock tower at the University of Texas, Austin. An autopsy revealed a tumor near his amygdala. That finding alone does not establish what caused his actions.

It is our brain, its anatomy, physiology and biochemistry and how these parts function that set the limits for how we think. But since our brain's parts also interact with our body's anatomy, physiology and biochemistry, we must see brain and body together. They are part of the same system - us.

Let's consider the anatomy of our brains to get a better understanding of what influences our behavior.

What we feel and think depends on neural connections

A lot is known about the brain, but far from everything. There are many controversies and unanswered questions.

Nobel Laureate Dr. Gerald Edelman, director of the Neurosciences Institute says:

The brain is the most complicated material object in the known universe. If you attempted to count the number of connections, one per second, in the mantle of our brain (the cerebral cortex), you would finish counting 32 million years later. But that is not the whole story. The way the brain is connected - its neuroanatomical pattern - is enormously intricate. Within this anatomy a remarkable set of dynamic events take place in hundredths of a second and the number oflevels controlling these events, from molecules to behavior, is quite large.

Weighing only three pounds, the brain is composed of at least 100 billion nerve cells or neurons. It also contains tens of billions of other cells called glial cells supporting neurons. Neurons are connected to other neurons and interact. Each neuron has a cell body with tiny branches called dendrites that receive information from other neurons. A long fiber called an axon carries signals away from the cell body.

Mental capacities depend on how neurons are organized and how they communicate, as well as on the cells themselves. Counting neurons alone cannot describe what a brain can do.

How do neurons connect and communicate?

Neurons communicate at junctions called synapses. At a chemical synapse, an electrical impulse reaching the axon terminal can trigger the release of a neurotransmitter. The chemical crosses a small gap and binds to receptors on the receiving cell. Depending on the signal and receptor, it can make that cell more or less likely to fire. The receiving neuron integrates signals from many inputs.

How does the neurotransmitter cause the electrical impulse? On the surface of the receiving neuron are proteins called receptors and every receptor is tailor made for a specific chemical. The chemical acts as a key, and the receptor, or the lock, only "lets in" the right chemical.

Why does it feel good when our loved ones give us a kiss or a compliment?

Dopamine is one of the chemicals involved in reward, motivation, and learning, and it also plays a role in addiction. Pleasure is not simply a matter of having more dopamine; several interacting systems contribute.

Serotonin also participates in mood regulation, but depression cannot be reduced to a simple shortage of it. Antidepressants act through different mechanisms; some alter serotonin signaling without mimicking serotonin’s structure. Neurotransmitters and drugs act within a system that includes cells, synapses, bodily processes, life experiences, and environmental conditions.

So far we know that the brain is a chemical system, and that neurons communicate with each other through the release of neurotransmitters (chemicals that carry messages between neurons). What we think and feel depends on chemical reactions. And these chemical reactions are a function of how our neurons connect. What determines how these neurons connect and their patterns? Our genes and life experiences, situational or environmental conditions, and a degree of randomness.

Genes control brain chemistry but are turned on and off by the environment

What is a gene? What does it do?

Genes are what makes an individual, for example, to be built with two blue eyes, two arms, one nose, and a brain with certain architecture.

Our body is made up of different types of interconnected cells functioning together. Most human body cells contain 46 chromosomes, with 23 inherited from each parent. Chromosomes contain DNA, or deoxyribonucleic acid, packaged with proteins. DNA is our inheritance; half is from our father and half from our mother. Genes are segments of our DNA and the units of our inheritance. A gene consists of four chemical molecules: adenine, cytosine, guanine, thymine or A, C, G and T joined together in a chain. The short chemical name for a chain of any number of these molecules, in any order, is DNA. The order of these molecules provides coded instructions for everything a cell does.

Many genes contain instructions for making proteins; others produce functional RNA. Proteins are molecules that carry out most of our biological functions and are made up of amino acids. There are twenty kinds of amino acids that can be used to make our skin, hair, muscles, etc. Some proteins act as enzymes that help chemical reactions occur, including reactions involved in producing neurotransmitters. Some hormones are proteins that carry messages between cells.

Sometimes a gene is "switched off" and can't make proteins. Messenger RNA is a genetic material that translates DNA into specific proteins. The Laureates of the Nobel Prize in Medicine, 2006, discovered a mechanism called RNA interference that could "switch off" a gene by blocking this process. RNA interference plays a key role in our defenses against viral infections.

Recent studies also suggest that genes do more than make proteins. For example, some genes produce RNA that helps regulate other genes without itself being translated into a protein.

Every living thing uses the same genetic code - from cats to humans. This means we can transfer a single human gene into a cat and the cat "can read it" and follow its instructions. But no individual has the same DNA or the same versions of genes (except for identical twins). Not all things are "spelled" alike. That's why people differ in eye color, height, etc. The closer related one living thing is to another, the fewer spelling differences. But even if the differences are small, gene expression - where and when they are turned on or off and for how long - is the key. As an example take our closest relative - the chimpanzee. Genetic studies show that humans and chimpanzees share at least 94% of their DNA sequences. This means that less than 6% of our DNA is responsible for the traits that make us different from chimpanzees. What causes the large difference in behavior? Studies show that the human brain shows strikingly different patterns of gene expression compared to the chimpanzee's brain.

Since we inherit all of our genes from our parents, why don't we look like a mixture of them?

In most organisms, genes come in pairs. For many genes, we inherit one version from each parent. When a father and mother's genes combine, the effect of one gene may dominate the effect of the other. Certain characteristics are dominant. Dominance helps explain why some inherited characteristics do not look like a blend of the parents’ traits. Eye color, however, involves several genes and cannot be predicted by a simple rule in which brown always wins over blue. A version that is not visibly expressed can still be passed to later generations, and recombination produces new combinations.

Some versions of genes are dominant, in some cases they blend, and sometimes we'll see an equal expression of both versions. Since several pairs of genes govern most traits, lots of combinations are possible.

Interaction and flexibility characterize our biological functions

Does each gene have its own specific part to play?

A gene can sometimes have a strong, identifiable effect, but many characteristics depend on several genes and their interactions. They are part of an interconnected system with many possible combinations. And most genes contribute to more than one characteristic. Genes can have different effects, depending on where, when and how they are switched on. Interaction is a fundamental property in biology. There are interactions between molecules, genes, neurons, brain regions, cells, organs and among these individual systems. Each system does its own job but they are all coordinated to produce a functional and unique individual.

But doesn't the left and right side of the brain have different functions? Dr. Ralph Greenspan at the Neurosciences Institute says:

... although in some sense it's poetic to speak of a "right brain/left brain'' difference. The fact of the matter is that things that are "right brain" are really happening everywhere and things that are "left brain" are really happening everywhere. There are certain aspects ofit that may be more biased to one side versus another, but the brain is not highly localized in any sense at all. Everything that ever happens in your brain is happening as a unification of many, many, many areas at once.

He continues:

Isaac Newton might have liked the neat view of biological systems made up of dedicated components, with causal roles that can be studied in isolation, and in which particular conditions give rise to uniquely predictable responses. Charles Darwin, by contrast, might

have felt more at home with the idea of a complex, emergent system made up of many non-identical components, with non-exclusive roles, non-exclusive relationships, several ways of producing any given output, and a great deal of slop along the way.

The most striking result of our interactive network is flexibility. A flexibility to take on new roles as conditions change and an ability to produce the same result in different ways. For example, studies show that different configurations between neurons can achieve the same result. The configuration depends on which alternatives are available at a given moment in a given situation (since behavior depends on context or situation), an individual's life experiences and an element of chance. Having alternative ways of producing the same outcome gives us a great benefit. For example, we can compensate for injuries and readapt to new conditions.

Do our genes have a life of their own?

Gene expression is regulated by processes inside cells and by signals from the body and environment. An outside event is not required each time a gene is expressed. Genetic differences can influence what the source calls "response tendencies." Experience and circumstances affect how those tendencies develop and appear in behavior.

Neural connections are shaped by life experiences

The brain changes continually as a result of our experiences. Experiences produce physical changes in the brain either through new neural connections or through the generation of new neurons. Studies suggest that the brain can change even during the course of a day. This means that the anatomy of the brain varies from individual to individual. Even identical twins with identical genes don't have identical brains. They have had different life experiences.

Experiences are the reason that all individuals are unique. There are no individuals with exactly the same upbringing, nutrition, education, social stamping, physical, social and cultural setting. This creates different convictions, habits, values and character. People behave differently because differences in their environment cause different life experiences. This is why it is sometimes hard to understand other people's behavior. To do that, we must adapt to their environment and share their experiences. This is often impossible.

If we encounter a stressful situation, how we respond depends on what we were born with, what we have experienced, and the specific situation. Assume that a person "Sam" and you both have genes for "being fearful." You are standing in a Savannah in Africa and are approached by a lion. Do both of you show the same reaction when exposed to the same situation? You are afraid but not Sam. Sam either knows that this lion is tame or Sam is a lion tamer. Sam's reaction comes from his life experiences. Sam may also be genetically predisposed to react differently to certain dangers. But even if Sam has a low genetic vulnerability to fear, he can develop a fear of the lion. One horrifying experience with a lion may be enough.

Behavior is influenced by our state of mind

Our life is what our thoughts make it.

• Marcus Aurelius Antoninus (Roman emperor and philosopher, 121-180)

Our state of mind is a function of our life experiences and the specific situation. Assume (1) we are eating tasty chocolate, listening to wonderful music and feeling relaxed or (2) we suffer from a cold, feel stressed and just ate a bad meal. If we have to make a judgment, will it be the same in both cases? Probably not, since our state of mind is different in case 1 and 2.

Can our state of mind influence our biochemistry and immune system?

It's not just what happens to us that counts - it's what we think happens to us. Expectations can influence symptoms and physiological responses, although they do not determine every health outcome.

Placebo effects are changes associated with the treatment context, including expectations and learned responses, rather than the treatment’s specific active ingredient. Improvement after taking a placebo is not necessarily all a placebo effect: symptoms can also change naturally over time.

The doctor gave me a pain-relief drug (when in fact it was a sugar pill) and after a short time I experienced significantly less pain.

A placebo is an inactive or ineffective treatment or substance (for example, sugar pills or injections with saline solution) that is often used in comparison with active treatments. Studies show that a placebo can improve a patient's condition simply because the patient expects it will work. Clinical evidence shows placebos to have physical effects on the brain, just as drugs do. Studies in Sweden show that a placebo activates the same brain circuits as painkilling drugs. Nine male students volunteered to participate in a study of painkilling drugs. Researchers first tested for the degree of pain the subjects would experience when a 48-degree Celsius metal surface was pressed to the backs of their hands. The test was repeated after the subjects were given a painkilling drug.

Later the subjects were told to test two new painkilling drugs and that one of these drugs was similar to the one they earlier tested. Once more the 48-degree metal surface was pressed to the backs of their hands. A man in a white coat, carrying a badge that said "professor", then entered the room. The "professor" gave the subjects intravenous injections of either an opioid (a drug acting like a drug made from opium) painkiller or a placebo. During the experiment researchers scanned the subjects' brains and compared brain responses. The account reports that both the painkiller and the placebo increased blood flow in brain areas rich in opioid receptors. A shared response does not mean that their effects were identical in every respect. Eight of the nine subjects said that the placebo produced a clear relief from the pain.

Other studies show that people who take sugar pills as a treatment for depression and other ills can undergo striking, although temporary, changes in brain activity and neural chemistry as their condition improves. It has also been shown that placebos can improve blood pressure, cholesterol level and heart rate. It's like a pharmacy inside the body that has evolved during million of years of evolutionary time.

What happens when a healthy person finds out he may die?

Negative expectations can influence symptoms and how people experience treatment. Associations between expectations and later illness do not, by themselves, show that the expectations caused the illness. In one study, women who expected that they were inclined to heart attack were nearly four times as likely to die as women with similar risk factors but without these expectations. Another study found that patients who were warned about the gastrointestinal side effects of taking aspirin were three times more likely to feel them. Other studies show that if people worry about drug side effects, they are more likely to get them. Beliefs have biological consequences - good and bad.

Our genes and life experiences determine how neurons connect thereby influencing and setting the limits for our behavior. We were born with the basics of life. We had neural connections that regulated our breathing, heartbeat, temperature, etc. How does our brain select those neural connections that produce useful behavior? Our brain is a product of evolution.