There has been a spate of books recently on the topic of neuroplasticity (type in neuroplasticity on Amazon and you'll get almost 1,900 results). "How God Changes Your Brain", published in 2009, is one of the most recent. It is the result of some rather exhaustive research done by a neuroscientist/therapist duo. If you don't believe me, check out pages 259-333, a full 74 pages worth of references.
So let's start with the "changes your brain" part. It is a reference to something called neuroplasticity, which is defined in the book as "the ability of the human brain to structurally rearrange itself in response to a wide variety of positive and negative events" (p. 14). The "How God" part refers to how various spiritual practices including meditation, can cause structural changes in the brain.
So here are some of the dramatic reports. "dendrites - the thousands of tentacle like receptors extending from one end of every neuron [...] rapidly grow and retreat in a period of a couple of weeks." And "recent evidence has shown that neuronal changes can take place literally in a matter of hours" (p. 15). Pretty heady stuff; your brain can alter itself in weeks and even hours. So why should you care about the brain's ability to create new neuronal connections? Here is why, "meditation can help maintain a healthy structural balance that will slow the aging process." Can you say "Om"?
There's more. Spiritual practice helps to reduce fear. From page 17: "Spiritual practices specifically strengthen the anterior cingulate and when that happens, activity in the amygdala slows down." What's the amygdala? It's is a pair of structures in the brain about the size and shape of an almond. They generate fear and cause the fight/flight response. So by slowing the activity in your little fear factory, you should feel less afraid.
Spiritual practice also reduces anger. "When you intensely focus on your spiritual values and goals, you increase blood flow to your frontal lobes and anterior cingulate, which causes the activity in emotional centers of the brain to decrease" (p. 20). For the curious, frontal lobe functioning is impaired when you get angry, causing you to become less rational and even lose track of your irrationality. As someone who provides marriage counseling, the idea of increasing a person's ability to control their anger has more than a passing appeal.
For those who say, I do sodoku and crossword puzzles so my brain is just fine thank you, listen up. From page 37, "meditation appears to be more effective when it comes to strengthening the neural circuits in your brain." And Swedish research shows that if you create your own memory enhancing program, the results will be even better.
I'm at page 103, and I am still glad to have discovered "How God Changes Your Brain." Chapter 5 (What does God look like) was a bit too heavy on detail for my tastes. But after meditating on it for a while, I started thinking, maybe chapter 5 is just fine...