Religion has long been a topic of philosophical discussion, but only relatively recently have neuroscientists begun to investigate faith and spirituality, too. Several different strands of research now indicate that there are specific parts of our brains that relate to belief in God, and that if certain parts of the brain are stimulated or damaged, it can lead to a dramatic change in faith or spirituality.

Endeavoring to investigate this question, Dr. Cosimo Urgesi of the University of Udine, Italy, led a study to assess the likelihood of self-transcendence (ST) in patients who had received brain surgery. Self-transcendence was defined as a decreased sense of self, with an ability to identify yourself as being “at one with the universe,” an integral part of it. The researchers assessed patients’ ST levels both before and after they had surgery, taking precise care to note exactly where brain lesions occurred as a result of surgery. They found that damage to the posterior parietal areas — usually associated with visuospatial processing, for example, being able to reach for an object, as well as the online representation of one’s own body (body schema) — caused changes in the patients’ self-transcendence, increasing the likelihood of a person experiencing it.

Yet it is not necessary to undergo brain surgery to experience a dramatic change in how you view your spirituality or beliefs; a substance called psilocybin appears to be very effective in this regard. In research at Johns Hopkins University during the past decade, psilocybin — the active ingredient in the sacred mushrooms used by Indian tribes in Central America as a religious sacrament for over 2,000 years — has been administered as the primary tool in exploring these alternative states of consciousness. Psilocybin is a tryptamine alkaloid, similar in structure to serotonin and dimethyltryptamine, which are produced naturally in the human brain.

Psychologist William A. Richards, of Johns Hopkins Bayview Medical Center, has conducted around 500 psychedelic therapy sessions. Given appropriate dosage in a supportive setting, many of these sessions follow a familiar pattern: The study participant reports initial sensory changes, often vibrant colors and patterns with closed eyes; then he/she may move on to a more introspective or psychodynamic stage, where personal life history and relationships may become focal. “Then,” says Richards, “a spiritual (or transpersonal) form of consciousness may become predominant, in which visionary imagery (of gods, goddesses, precious metals and stones, ancient civilizations and/or cosmic panoramas) may occur, finally opening into unitive-mystical states of awareness beyond the limits of the usual everyday personality. This phase often entails a reported sense of oneness and interconnectedness, as well as intuitive insights about religious and philosophical issues such as the ultimate structure of reality and immortality.”

It’s tempting to view studies such as this with suspicion. The fact that people undergo spiritual experiences while under the influence of a mind-altering chemical could be as meaningless as a person who feels more confident when they are drunk. But results indicate that this is not the case. Professor of psychiatry and neuroscience Roland R. Griffiths, also of Johns Hopkins University, has worked with Richards on some of the psilocybin studies — and their results indicate that the effects of the psilocybin experience are not just profound; they are also long-lasting. When Griffiths and his study’s co-authors followed up with participants 14 months later, more than half maintained that the experience had been among the five most spiritually significant experiences of their lives, with 64 percent saying that the experience had increased their well-being or life satisfaction.

So if physical changes to the brain can create religious or spiritual experience, does religious experience also cause changes to the brain? Possibly. Researchers at Duke University Medical Center analyzed data from 268 older adults, using high-resolution MRI images to assess hippocampal volumes in relation to life-changing religious experiences. They found that those who had experienced such life-changing events had significant hippocampal atrophy compared to those who hadn’t. The researchers can’t say for certain just why this should be so, and they are keen to point out that no causal relationship has been shown. One theory is that the atrophy is caused by stress. The study participants who considered themselves dedicated to a religion but had not had a life-changing religious experience didn’t show the same atrophy in the hippocampus. So the researchers suggest that sudden and dramatic change in religious beliefs — such as becoming a born-again Protestant or Catholic, as many of the affected study participants did — could cause stress to the individual as they struggle to adjust or come to terms with their new beliefs. Stress is known to reduce the size of the hippocampus.

We know that the environment we live in affects our religious and spiritual choices; now there appears to be substantial evidence indicating that we are also biologically programmed for some kind of faith or spirituality. But why? Matthew Alper, author of “The ‘God’ Part of the Brain,” was one of the first philosophical thinkers to investigate this question, amassing a wealth of scientific evidence to support the idea, which, he says, is fairly straightforward: “Every culture, from the dawn of our species, has believed in some form of a spiritual realm, in spiritual entities [gods] and a soul that perseveres after physical death.”

He says there are two distinct instincts at work here: the religious and the spiritual. “The function of the religious instinct is to strengthen the group dynamic by providing societies with a set of spiritual norms, guidelines, and rituals that bond and regulate the community,” he says. “The spiritual instinct constitutes a more sensory experience — often prompted by prayer, chant, or meditation — that calms and comforts us by releasing us from the psychic strains of daily life as well as the debilitating anxiety that comes with our species’ unique awareness of death. As we tend to interpret this altered state as a feeling of being connected to a ‘higher’ power, it acts to bolster our beliefs.”

So if there is a function or purpose for believing in god, or having faith in something beyond ourselves — as well as a part of the brain used for this purpose — why do some people not indulge in this kind of behavior? What of the atheists and agnostics of the world?

“As with any inherent predisposition — be it for music, math, or language — we fall into what we could call a ‘cognitive bell curve,’” Alper says. “Every human culture has, for example, displayed a proclivity for music. This suggests that there must be parts of our brain which provide us with this capacity. Though our species possesses this inherent proclivity, because of genetic variance, however, each individual is born with a particular musical potential that falls somewhere into a bell curve. Whereas most of us are born with average musical potential — representing the bulge of this curve — on the tapering extremes some are born gifted while others are tone-deaf.”

Alper applies the idea of a cognitive bell curve to religiosity and/or spirituality. “The majority of humans will possess an inherent predisposition to believe in a spiritual reality, [and] there will be those on the tapering extremes of this same curve who will be less inherently inclined to believe in a spiritual world or practice a religion. On the opposing side of that same curve, there will be those born spiritually and/or religiously gifted; those whose religious and spiritual beliefs will play a more important role in their conscious experience.”

Just as with music, he says, we shouldn’t ignore the important role that one’s environment plays in one’s religious/spiritual proclivities. “Therefore, I would say that spirituality and religiosity — as would be true for any inherent set of behavioral predispositions — is dependent on the interplay of one’s nature and nurture.”

This article was originally published in Brain World Magazine’s Winter 2012 issue.

Related Articles