Heavenly Minded and Earthly Good
The brain is commonly said to contain around 100 billion neurons (though some recent research suggests it may be only 84 billion). Each neuron—or nerve cell—is connected to a thousand of its fellow neurons. So this gives the brain about 84–100 trillion connections between neurons. If neurons were the size of dollar bills, 100 trillion of them sewn together would make a carpet covering Texas and California combined. That’s a lot of neurons in a relatively small space.
Now consider this: Each of the trillions of connections between neurons can have various states. Computers have binary signals, ones and zeroes, on and off, as their basic signaling device. Neural connections may have ten or more possible states at just one of the 84–100 trillion junctures. This is why the brain is considered by many to be the most complex thing in existence. Fully understanding how the brain processes vision—with some neurons dedicated to processing movement, others to color, others to shapes, others to faces—is a task well beyond current science. But what we do know gives us a window into how God may use the brain to transform us.
How the Brain Works
Neurons communicate through a mix of electrical and chemical signals. Those signals can change, increase and decrease in strength, or develop from scratch. One neuron receives signals from another through its dendrites, which have a branch-like structure. They send an electrical impulse up their branches into the body of the neuron and then out through one or more of their many axons, which also look like branches. At the tip of the axon is the synapse, a gap between two nerve cells. Here the electrical signal in the cell changes to a chemical one, with chemicals being released at the tip of the axon to be received into “ports” in the dendrite of the next neuron.
Much of the growth and development in the brain occurs in our synapses as we learn. Most medications that affect mood and behavior change the strength of the chemical signal passing through the synapses. This is where brain chemicals such as dopamine or endorphins come into play.
Using these neurotransmitters (the chemicals that jump across synapses), neurons communicate, and their ability to communicate increases the more they work together. The chemical signals sent from one side of the synapse become stronger, and the receptors on the other side become more sensitive, better able to pick up signals. As we learn a new activity, new information, or even a new dance step, neurons are strengthening these signals between existing nerve cells, and creating new connections with other nerve cells.
The brain does more than passively wait for input from the body and process it. The brain is always on alert, searching for new information and improving how it processes information, learning—and learning how to learn. Our brains will employ a host of neurons to help us learn, but as we gain proficiency, we need fewer nerve cells, which become specialized and fuse more tightly. They create neural pathways, a kind of high-speed internet cable in the brain.
Experience is constantly changing our brains. The cerebral cortex—the wrinkled outer layer of the brain involved in high-level thinking—gets heavier as it learns. It is 5 percent heavier in laboratory mammals raised in learning-enriched environments. Rats that are trained to solve mental problems have higher levels of acetylcholine, a chemical necessary for learning, in their brains. Neurons in those stimulated regions grow larger, developing 25 percent more branches to connect to other neurons. This extra work demands more blood supply. Examinations of human brains after death show that people with more education tend to have larger brains, because of these extra connections. So if the average brain has up to 100 trillion connections, a highly educated one will have many more. This physical learning process means that learning something new doesn’t necessarily require forgetting something old. By increasing the brain’s synaptic connections, we can also increase its capacity.
The brain is in many ways like a muscle, growing stronger the more it’s used. It has a basic structure or mode of operation, but within that framework it’s surprisingly flexible—even into old age and even after diseases hamper its function. While the extreme but necessary neural nimbleness of youth is lost shortly after adolescence, the ability of the brain to change and grow throughout life is only now being understood.
Building Neural Compassion
All this should encourage us; we are not set in stone. We can and do change dramatically. In addition to the change that occurs naturally over time, we can also choose to pursue other changes. Researchers in fact have been looking at how to create the brain changes that lead to other changes we desire.
And yet the brain is a conservative organ. Despite its capacity for change, it only changes significantly under certain conditions. For example, we must monitor closely what we are doing. We do not improve our brains while surfing the Internet, flipping stations, or checking Facebook. Many experiments have shown that neurons changed in an inattentive experience revert to their original state shortly thereafter. Lasting change requires the kind of attention that many of us find difficult.
The attention required in spiritual practices like deep prayer, contemplation, study, and worship is what the brain needs to grow in lasting ways. Neuroscientist Andrew Newberg, who studies spirituality and the brain at Thomas Jefferson University, found that eight weeks of meditation can create measurable changes in the brain. It can take just two weeks, and sometimes even less, for neurons to grow new axons and dendrites, making new connections to other neurons and making new learning a physical feature of the brain.
Newberg also found that this kind of spiritual practice is unique in the way it changes the brain. Any kind of learning or concentration will cause the brain to change. “But religious and spiritual contemplation changes your brain in a profoundly different way because it strengthens a unique neural circuit that specifically enhances social awareness and empathy while subduing destructive feelings and emotions.” That’s what makes spirituality particularly healthy for your brain.
In addition to attention, the emotional nature of spiritual experiences helps us to change as well. Prayer and other spiritual practices like worship are more than cognitive exercises; they connect us with God. Sometimes that connection is felt: we sense a closeness to God. That can be emotionally powerful, and powerful emotions create neural instability. The connections between neurons loosen up, allowing new connections to form. As Newberg and a co-author put it, “This increased emotional discharge [brought on by feeling close to God] is known to cause a certain degree of neural instability, allowing for the forming of new connections between neurons.”
Spiritual exercises combine all these ingredients: attention, practice, and from time to time emotion. In his book Prayer: Does It Make Any Difference? Philip Yancey writes that his fellow author Brennan Manning told him that no one had ever failed to hear from God during one of the retreats Manning had led. There were just a few expectations for the retreat, including worship and some guidance from Manning, but the one rule was to spend two hours a day in prayer. Hearing from God isn’t merely something that happens on special occasions in life.
The brain, according to Newberg and a number of other neuroscientists, seems wired for spiritual experiences. This feeling of connection to God (and note that the great Christian mystics warn against putting much emphasis on feeling) seems to lead to better health and better brain function. But of course, sticking your cranium into a brain scanner while you feel close to God doesn’t prove that you are indeed communing with him. We cannot make direct causal links between the God of the universe and the changes in our neurons. As much as we learn through science, we also humbly admit that we enter mystery when we speak of communing with God.
We also can’t guarantee that a little bit of meditation will heal our depression or make us the people we want to become. Researchers believe that only about 40 percent of your happiness is actually under your control. The bulk of the rest is due to your natural predisposition, and a tiny sliver depends on your circumstances, such as winning the lottery. We are not endlessly malleable.
But we can take comfort. God seems to have designed us with a biological process for seeking him and for renewing our minds. We may rely on God’s grace from start to finish here, but it isn’t all in the realm of ethereal mystery. Grace, as Dallas Willard said, isn’t opposed to effort. We can use our brains to fix our minds on Jesus. There may result any number of useful outcomes. But the point of prayer, of course, is not to change our neurons, but to orient ourselves in a posture of sitting at the feet of a loving Creator.
Rob Moll is a Christianity Today editor at large. This article is adapted from his book What Your Body Knows About God (InterVarsity, 2014).
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