Sermon illustrations

The Brain

The Alarm System

What happens in the brain when we are afraid? Remember the little red metal square on the school-room wall with a piece of glass that reads, “Break in case of fire”? Just as the school has a fire alarm, so, too, our brain has an alarm switch called the amygdala…When the fire alarm is activated at the school, its job is twofold: first to grab the attention of everyone in the building, and second to alert the 911 operator.

Like that fire alarm, the amygdala both releases attention-getting adrenaline from the adrenal glands to the brain, and it alerts a sort of 911 operator to send out an urgent call. The brain’s 911 operator is the hypothalamus, which is connected to the “radio tower” of the pituitary gland. Instead of radio waves, the pituitary gland transmits hormonal signals calling for the body’s emergency response, which comes from the adrenal glands; they’re the stress steroids known as glucocorticoids.

When emergency responders arrive at the school fire, there is a fire chief who assesses the extent of the blaze and how many responders are on the scene. When there are enough firefighters, the chief calls back to the 911 operator and reports that, even though the alarm is still going, the operator doesn’t need to send any more.

Back in the brain, hippocampal neurons are the fire chief. They have glucocorticoid receptors that recognize the rise in stress hormones and signal back to the 911 operator (hypothalamus) saying, “Okay, you don’t need to call any more responders (stress hormones).” Then, after the alarm has sounded, the brain’s administrator, which is the dorsolateral prefrontal cortex (DLPFC, the part of the brain right behind the forehead), acting much like the school principal, evaluates whether there is real danger or whether it was a false alarm. If the administrator determines there is real danger, the alarm gets louder. If the administrator determines that there’s been a “false alarm,” everything calms down.

Taken from The God Shaped Brain by Timothy Jennings Copyright (c) 2017 by Timothy Jennings. Published by InterVarsity Press, Downers Grove, IL. www.ivpress.com

The Brain Consists of…

The average adult brain consists of more than 10 billion neurons communicating with one another through more than 10 trillion synaptic connections. (Synaptic connections are the junctions or gaps between the axon and the dendrite of a neuron.) As unbelievable as it sounds, the number of possible neuronal connections in the brain is more than all of the stars in the known universe (approximately 50 billion galaxies with an average of 100 billion stars each). Although the average dendrite is a fraction of a millimeter in size, if you were to line up all the dendrites in your brain, the line would circle the globe five times!

Gregory Boyd and Al Larson, Escaping the Matrix: Setting Your Mind Free to Experience Real Life in Christ, Baker, 2005, p.31.

The Brain Over Time

Neuroimaging has shown that as we age, our cognitive center of gravity shifts from the imaginative right brain to the logical left brain. At some point, most of us top living out of imagination and start living out of memory. That’s the day we stop creating the future and start repeating the past. That’s the day we stop living by faith and start living by logic.

Mark Batterson, If: Trading If Only Regrets for God’s What if Possibilities, Baker Books.

Changing Someone’s Mind (Isn’t Easy)

A mind is more like a pile of millions of little rocks than a single big boulder. To change a mind, we need to carry thousands of little rocks from one pile to another, one at a time. This is because our brains don’t know how to rewire a full belief in one big haul. New neuron paths aren’t created that quickly. You might be able to get a tiny percent of someone’s mind to rewire to a new belief in a given conversation, but minds change slowly and in unpredictable ways. You might be changing it in the wrong direction.

Buster Benson, Why Are We Yelling? Penguin Publishing Group, 2019, p.19.

Dopamine and the Desire for More

The brain’s reward center, which includes the production and release of dopamine, pushes us toward both making and spending money, playing video games, use or overuse of the internet, and consumption (even binge consumption) of the latest Netflix series. Dopamine even spikes when you hear the hook to your favorite Beyoncé jam on your bumper-to-bumper morning commute.

Yes, pop music produces almost addictive brain chemistry. Every compulsive thing works on the same neurological systems. And though different whizz-bang chemicals might be involved in sex, drugs, and rock-and-roll, one neurotransmitter is common—dopamine. It’s the neurotransmitter that locks the memory of the whizz-bang in place, that drives our desire.


And again.

And again.

Priming us for more, more, more.

Seth Haines, The Book of Waking Up, Zondervan, 2020, p.134.

The Importance of the Prefrontal Cortex

The prefrontal cortex is responsible for the success of the human species. It enables us to learn from our mistakes and make plans. When the PFC is healthy, we behave consistently in ways that enable us to reach our goals. When it works as intended, we are organized, goal directed, thoughtful, empathetic, and able to express feelings appropriately. The PFC is often called the executive part of the brain and is closely associated with judgment, impulse control, attention span, self-monitoring, problem solving, and critical thinking.

The prefrontal cortex is the brain’s brake. It stops us from saying or doing stupid things. I was once at a conference with a 42-year-old friend I’ll call Joelle. She had been in a car accident that damaged her PFC a few years earlier. As we sat waiting for the next presentation, we overheard two women in the row in front of us talking about why they were heavy. One said to the other, “I don’t know why I’m overweight; I just eat like a bird.” In a voice loud enough for everyone around us to hear, my friend said, “Yeah, like a condor.” Horrified, I gave Joelle a look that asked, Why would you say that out loud? Meanwhile the embarrassed and angry women moved away from us. Joelle put her hand over her mouth and said, “Oh no, did that get out?”

Taken from Daniel G.Amen, Memory Rescue: Supercharge Your Brain, Reverse Memory Loss, and Remember What Matters Most, Tyndale House Publishers, Inc.

Keeping the Body From Overheating

According to the ancient Greek philosopher Aristotle, the function of the brain was to keep the body from overheating. In The Parts of Animals, he noted that that the brain was a “compound of earth and water, which “tempers the heat and seething of the heart.”

Stuart Strachan Jr.

Humanity vs. A Computer

In February 2011 human brainpower faced off against Watson, IBM’s supercomputer, in a battle of knowledge and processing speed on the popular TV show Jeopardy. Who would win? Ken Jennings and Brad Rutter, the top two all-time Jeopardy winners, or Watson, IBM’s synthetic creation? After three intense matches, Watson had defeated the human competition. Watson’s win had some fearing that computers had finally advanced beyond the human brain. But, I say, not so fast—let’s do a little comparison between Watson and a human brain and see how well the human brain stands up.

Watson is composed of 90 IBM Power 750 servers, each 6.9 inches high, 17.3 inches wide, 28.7 inches deep and weighing 120 pounds, for a total weight of over 10,000 pounds—housed in 10 large racks in a room approximately 12 feet by 10 feet.1 Watson contains 2,880 Power7 processors, with each processor consisting of 8 cores containing 1.2 billion transistors and 16 terabytes of RAM,2 processing 500 gigabytes of information per sec (1 million books/sec).3

In comparison, the human brain weighs about 3 pounds and is contained within the small space inside the skull. The brain is estimated to have more than 100 billion nerve cells and over one trillion supporting cells. Each nerve cell can have up to 10 thousand connections to other nerve cells, which makes the brain highly interconnected with some estimates of over a quadrillion connections.

The human brain holds approximately 1.25 terabytes of data and performs at approximately 100 teraflops5 (one hundred trillion point operations per second). Watson holds 1 terabyte of data and performs at 80 teraflops (eighty trillion point operations per second).6

In addition to actually having greater speed and storage capacity than Watson, the human brain, being housed in the body, is highly portable and can choose to move itself from place to place; Watson cannot. The human brain can experience emotions; Watson cannot. The human brain can rewire itself based on new experience or a change in understanding; Watson cannot. The human brain can grow new components (neurons); Watson cannot. Ultimately, the human brain turns out to be the most marvelous piece of engineering known, far beyond human ingenuity and immeasurably more complex than Watson.

Then why did Watson win? According to Ken Jennings, it had nothing to do with knowledge or ability to answer the questions. It all came down to who could ring in fastest. Jennings said in an interview after the competition, “Jeopardy! devotees know that buzzer skill is crucial—games between humans are more often won by the fastest thumb than the fastest brain. This advantage is only magnified when one of the ‘thumbs’ is an electromagnetic solenoid triggered by a microsecond-precise jolt of current.

Taken from The God Shaped Brain by Timothy Jennings Copyright (c) 2017 by Timothy Jennings. Published by InterVarsity Press, Downers Grove, IL. www.ivpress.com

Our Brains are Hungry

Even though your brain makes up only about 2 percent of your body’s weight (about three pounds), it uses 20 to 30 percent of the calories you take in, as well as 20 percent or more of the oxygen and blood flow in your body. The brain uses its approximately 86 billion neurons, which fire 18 trillion times a second, to perceive and analyze incoming data; decide what, if anything, to do about it; and then execute your responses.

Taken from Daniel G.Amen, Memory Rescue: Supercharge Your Brain, Reverse Memory Loss, and Remember What Matters Most, Tyndale House Publishers, Inc.

Which God Do You Believe In?

Does it matter which God-concept we hold to? Recent brain research by Dr. Newberg at the University of Pennsylvania has documented that all forms of contemplative meditation were associated with positive brain changes—but the greatest improvements occurred when participants meditated specifically on a God of love.

Such meditation was associated with growth in the prefrontal cortex (the part of the brain right behind our forehead where we reason, make judgments and experience Godlike love) and subsequent increased capacity for empathy, sympathy, compassion and altruism.

But here’s the most astonishing part. Not only does other-centered love increase when we worship a God of love, but sharp thinking and memory improve as well. In other words, worshiping a God of love actually stimulates the brain to heal and grow.

Taken from The God Shaped Brain by Timothy Jennings Copyright (c) 2017 by Timothy Jennings. Published by InterVarsity Press, Downers Grove, IL. www.ivpress.com

See also Illustrations on Attention, The Body, Ideas, Memory, The Mind, Thought/s

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