Brain Health

Sin: How Does Neuroscience Explain It?

As an open flame attracts a moth, an encounter that can end fatally, certain things in life lure us as humans. Whatever one wishes to refer to the attraction of sin, e.g. mistakes, vices or transgressions, does not change their grip on all of us. Is there something intrinsic about being a human that makes us more susceptible to sin? Is original sin programmed in us?

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Within the last few decades, neuroscience research has soared exponentially. To give you an example, the number of articles with the keyword “neuroscience” has doubled in the last seven years from what was published the preceding seventy years. We are indeed in the age of neuroscience. It is like an evolving tool with many applications.

More than ever, we can scientifically address the root causes of a person’s behavior that ultimately predict chronic disease. Intriguingly, texts from ancient times address behavior in the context of religion and philosophy. An estimated one-third of the world’s population is Christian, the largest religious group. The Bible is the source of Christian teachings, rooted both in Judaism and the teachings of Jesus Christ, and the most read book worldwide.

Neuroscience articles are increasingly being published.
Pubmed search for “Neuroscience” showing dramatic increase in publications

Is it possible to explain some of the teachings of the Bible with a neuroscience framework? Interestingly, an explanation of sin parallels what we have learned in neuroscience. I will attempt to explain the salient points to illustrate the driving force of sin.

The Source and the Seven Deadly Sins

In the NIV Bible, the word “sin” appears 474 times; about three-quarters of the references are in the Old Testament. With such an emphasis on the term, the Bible clarifies that this is one of its essential instructions. The story of Adam and Eve informs us of humanity’s separation from God when the serpent convinced Eve to take from the Tree of Knowledge of Good and Evil. After Eve offers the fruit to Adam, he accepts. The two are separated from God and the Garden of Eden, realizing they were naked for the first time. Thus, began the cycle of human sin after this original sin.

In Exodus 20:2-17, God gives Moses ten laws, or commandments, which the Jews, having departed from Egypt, must follow. Eight of the ten commandments include “You shall not,” wherein lies the object of sin. These commandments cover sins of idolatry, murder, adultery, stealing, lying, and profanity. Pope Gregory 1 conceived of seven sins as recorded by the Bible in the Ten Commandments: pride, envy, wrath, gluttony, lust, sloth, and greed. He coined them the “seven deadly sins.”

An excerpt from Isaiah 14:13-14 breaks down the root source of sin as pride and selfishness. “You said in your heart, I will ascend to the heavens; I will raise my throne above the stars of God; I will sit enthroned on the mount of assembly, on the utmost heights of Mount Zaphon. I will ascend above the tops of the clouds; I will make myself like the Most High.”

What is pride? Is this a flaw that is built-in being human- a weak nature that we all have?

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Hedonotropism? A Step in the Direction of Neuroscience

Scientists use “tropism” to describe when an organism turns towards or away from a stimulus. We have a natural tropism towards things that please us and away from things that cause us harm. The greater the pleasure, the more attractive it is to us. The more something attracts us, the more it fills our attention and the greater likelihood of repeating it. In the interplay of attraction and engagement, there are powerful forces in play.

The limbic system includes structures that organize emotions and a person’s response to pleasure and pain; they involve the amygdala, the hippocampus, and the hypothalamus. Neural tracts connect these brain areas with the brainstem and spinal cord, effectively linking the rest of the body. Chemicals known as neurotransmitters coordinate the signals which drive cellular metabolism and create an effect.

Neuroscience findings relate functions for the limbic structures: 

  • The hypothalamus controls many of the regulatory aspects of an organism, including hunger, thirst, sexual arousal, and sleep/wake.  
  • The amygdala is responsible for emotions, social awareness, fear, and anger. The cingulate gyrus links heart rate and blood pressure control to attention and emotions. The amygdala changes in the setting of anxiety and depression. For instance, neuroscience studies have shown larger amygdalar volume in people with major depressive disorder.
  • The hippocampus is the brain’s memory center, reminding us of actions that lead to pleasure and those that lead to harm. 

Many essential functions require having motivation and satisfaction built-in. A palatable meal brings pleasure and a strong attraction to repeating it. Sexual intercourse results in a release of pleasure hormones that ensure one repeats it for greater chance to have offspring.

The critical neurotransmitters involved in the repetition of an activity that brings pleasure are dopamine and serotonin. Dopamine relates to the movement toward a positive stimulus, and serotonin keys us into satisfaction. A simple thought of behavior that led to pleasure can increase dopamine release in anticipation. When someone repeats an action that led to delight before, dopamine floods the synapses of the limbic system and promotes the effect. 

Signals originating from the hypothalamus (hypothalamus-pituitary-adrenal (HPA) axis) affect the body’s response to the stimulus. These changes include increased heart rate, blood pressure, and cortisol release. Therefore, excess dopamine states can lead to perturbations in the body’s ability to maintain homeostasis. The body may respond to excessive dopamine states through feedback mechanisms by adapting and becoming resistant to them.

Dopamine resistance: The origin and effect of sin?

Repeated actions that trigger high dopamine release eventually degrade the signal, and the response diminishes as dopamine receptors (DR2) down-regulate. Interestingly, in this way, the brain protects itself from excess stimulation, which can dysregulate the body. The effect of downregulation is one of an increasing need for a greater amplitude, i.e., of behavior or substance, to produce similar results. The result of extra dopamine release corresponds to the drives that someone has when they become dependent and addicted to a behavior or substance that ultimately becomes destructive.

What do we mean by destructive? Let’s start with rats. Brain measurements showed that rats need more stimulation for a reward after being fed a continuous supply of a high-fat diet. An improperly functioning dopamine reward system leads to “seeking,” compulsive behaviors, or self-control difficulties. 

Neuroscientists use imaging studies to help define what happens in the brain of someone who has an addiction. Whether the addiction is sugar, alcohol, or drugs, common changes occur to the brain. There is a loss of gray matter in certain areas and enlarging areas related to fulfilling the dependence cycle. Biologically, the fMRI suggests decreased oxygenation to the regions of the brain that atrophy. The prefrontal lobe, a part of the brain that functions in cognition, judgment, problem-solving, and social behavior, takes a toll. Severe gray matter changes also occur in the hippocampus, cingulate, limbic, and paralimbic areas with drug use. These areas relate to memory, motivation, and rewards.

Addiction ultimately leads to changes in dopamine transport, possibly from the loss of dopamine-producing cells. Together with the gray matter changes, there are deficits in memory, motivation, and dopamine that plague a person who is addicted. 

In that way, a part of a person is lost with addiction, as the brain becomes more streamlined to continuing a habit. Abstinence does lead to a bolstering of these gray matter declines up to a point, for instance, in methamphetamine or alcohol dependence. 

A condition known as dopamine dysregulation syndrome can result after taking dopamine therapy in people with Parkinson’s disease (PD). Higher doses and shorter-acting agents increase the risk of this syndrome. It can result in behaviors such as dopamine medication craving, gambling, and increased sexual behavior. People may develop impulse control behaviors, including eating disorders, punding, compulsive shopping, aggression, and psychosis.

When the continuous supply of dopamine stops in a person who is dopamine deficient or “dopamine resistant,” they may go through dopamine withdrawal. The state is similar in patients with Parkinsonism who abruptly stop their dopamine medications. It comes with a maelstrom of unpleasant results, including increased pain, fatigue, nausea, vomiting, anxiety, adrenal insufficiency, and intense cravings, as one exposes themselves to a massive physiologic response.

The Pendulum of Behavior

Imagine behavior as a pendulum. The greater the swing in one direction, the more amplitude the return is. Effectively, if a person searches for pleasure, they are less likely to find it—the cycle known as the pleasure paradox. The substance or extreme behavior imprisons them.

We can become dependent on any substance that triggers an excess release or reduction of degradation at the synapse. The greater the trigger of dopamine, the more attracted we are to repeating it. The behavior becomes the person’s focus. Likewise, all seven deadly sins represent behaviors for which there is biological programming – but to an unhealthy extreme. 

Behavior is a pendulum and sin can result from extreme behaviors.
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The Sin of Lust: A Programmed Behavior Taken to the Extreme

The attraction between two humans, e.g., a male and female, is made possible through hormone signals. Testosterone is the hormone that surges in males during puberty and signals testicular development, muscle mass, bone growth, pubic hair, and sperm development. In women, testosterone may also be responsible for sexual behavior. Estrogen prepares the female for pregnancy, exerting changes on the vagina, uterus, breasts, and the entire body. The hormones drive not only physical but also behavioral changes. 

Functional MRI (fMRI) studies on sexual desire show neural circuitry that develops within the brain’s reward, emotional, and expectation centers (here are the specific areas). The imaging suggested that, from desire, love branches different pathways that may represent more abstract and habitual learning (Seok, 2016; Cacioppo, 2012). Here is a YHF article that dives deeper in the difference between romantic love and long-term relationships.

The sexual hormones enable partners to develop an intense attraction to ensure the continuation of the species. The brain recruits the entire body to experience this arousal, including hormonal mechanisms, the autonomic and sensory nervous systems. When taken to its extreme, thoughts, pornography, multiple partners, frequent experiences, and more intense sexual desire lead to a roller-coaster ride of hormones, emotions, and displeasure. The behavior begins to take a stranglehold on one’s life as dopamine deficiency. As actions materialize from thought, the ramifications of the sin unfold.

What does Neuroscience Tell Us About the Sin of Murder?

Since the pandemic, the CDC estimates that the murder rate is up 30%. Recently we heard in the news that 22-year-old Gabby Petito was tragically killed by strangulation- her body left stranded in Grand Teton National Park. The prime suspect is her fiance’ Brian Laundrie, who accompanied her and is now a fugitive.

Homicide data shows that 41.8% of murders occurred during arguments, including romantic triangles; an additional 23% were during felonies, such as burglary. Non-strangers, like in the case of Gabby Petito, commit the majority of violent crimes.

While murder and other violent crimes are undeniably moral wrongs, most killings are crimes of passion, stemming from emotional dysregulation. Often included in a person’s history are significant environmental perturbations, including a history of severe abuse and head trauma. “Hurt people hurt people.”

One way to approach the neuroscience of violent crimes is to look at the structure and function of prisoners’ brains. For example, brain tumors or injuries and trauma to certain regions can increase the risk of impulsive and deviant behaviors. 

A schoolteacher convicted of child molestation had a brain tumor in the right orbitofrontal area identified on MRI. He was otherwise healthy until he developed an interest in child pornography before his crime. Scientists suspected that the tumor disrupted emotion and decision-making pathways from the tumor site to the amygdala (Straiton, 2021). Additionally, imaging studies have revealed other changes in specific brain areas in convicted criminals and persons with psychopathy, including grey matter volume in the prefrontal cortex (Straiton, J, 2021). 

There was also consistent evidence linking past traumatic brain injuries to an increased risk of criminal activity. The findings support a relationship between traumatic damage and emotional impairments. Convicted serial killer John Wayne Gacy, responsible for the murder of 33 men, had a moderate traumatic brain injury while being abused by his father at the age of eleven. Significant emotional abuse and neglect are other forms of brain trauma.

Similarly, functional MRI studies on violent offenders show decreased prefrontal cortex gray matter and increased limbic activity (e.g., amygdala). The area is the same as the rewards center. Activity correlates with increased aggression, impulsivity, and emotional dysregulation.

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Summary: Understanding the Consequences of Sin

When we think of the heart pumping, we accept that it is a required function to live. The pathways in the brain that coordinate our behaviors similarly are necessary to thrive and drive us to develop behaviors of self-preservation, socialization, and pro-creation. The brain completes these tasks both voluntarily and involuntarily. Nevertheless, these normal pathways can become dysfunctional and disruptive, sometimes as a result of an adaptation to traumatic experiences, including head injury, abuse, and neglect.

We are driven by forces that are subconscious, as well as conscious. We are not always aware of our tendencies until an action – to oneself or others – is committed to remind us. As we develop less-healthy coping strategies that use up our mental resources, we constrain ourselves from growth and increase internal stressors. These, in turn, lead to perturbations within our body which damage us, causing inflammation that promotes disease and mental anguish.

Neuroscience tells us that a sin is essentially an action or thought, formed by preceding behaviors, that captures us in a cycle of fleeting pleasure. The cycle exposes a person to increased displeasure and harm. Eventually that person- and those around them- become affected by these actions.

In Matthew 13:44-46, Jesus taught that the “kingdom of heaven is like a merchant looking for fine pearls. When he found one of great value, he went away and sold everything he had and bought it.”

Conversely, perhaps sin is like a shiny pearl on the trail to a healthy, creative, thriving life. In hardships, our brains may take us to the sides of the path, distracting us to look for what glimmers along it. When we find a pearl, it never shines as brightly as when we first saw it. And we spend our time trying to make it to shine, never realizing that our life gets consumed by it.

Sin is a harmful distraction in the path of health and fulfillment
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“First the man takes a drink, then the drink takes a drink, then the drink takes the man.”

Edward Rowland Sill (1886)


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Straiton, J, Lake F. Inside the brain of a killer: the ethics of neuroimaging in a criminal conviction. Biotechniques, vol 70(2). Article

Williams W, et al. Traumatic brain injury: a potential cause of violent crime? 2018. Lancet Psychiatry Oct: 5(10): 836-844.

Other references are included in the article.

Categories: Brain Health, neuroscience

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