Between 1967 and 1970, neurologist and Korean War veteran William Caveness started an unusual collection. He gathered information on roughly 2,000 Vietnam War soldiers who suffered traumatic brain injuries during combat, recognizing that their tragic accidents could serve another purpose—studying the long-term effects of such injuries on the brain.
As a dataset, the soldiers were unique. They had undergone neurophysical and intelligence testing before enlisting, offering the rare opportunity to compare cognitive ability before and after injury. The Vietnam war was the first widespread use of helicopter evacuations, and the soldiers were treated quickly by nearby neurosurgical teams. This meant they actually survived their injuries, unlike many in past military conflicts. Due to lower-velocity shrapnel wounds, the parts of their brains that were damaged were hyper-localized. These conditions created a group of diverse and stable men, with very specific brain lesions, all willing to be studied.
Jordan Grafman, director of brain injury research at the Shirley Ryan AbilityLab, called them "the gift that keeps on giving." He's been working with the data from the Vietnam Head Injury Study for years, publishing papers on the neural basis of problem solving, the connection between aggression and brain damage, caregiver behavior and mental decline, and other topics in the slippery realm of neuropsychology.
In April of this year, Grafman and his co-authors published the latest of their work that attempts to use the vets' brain lesions to explain an even more abstract phenomenon: mystical and religious experiences, and religious fundamentalism.
Subjects with brain damage have always been useful for neuroscience. Famous cases like H.M. and Phineas Gage allowed scientists to infer what parts of the brain did, based on what their subjects were lacking. Irene Cristofori, a co-author on Grafman's studies, says that most work on religion and the brain is correlational: It shows activation in certain brain regions during religious behavior or thought. But working with lesion patients can offer more. They can claim causation in their findings, that the parts of the brain they implicate have a crucial role in those powerful moments between an individual and god.
Neuroscientists have long been curious about the neural basis of religion. One quarter of patients with epilepsy affecting the frontal and temporal lobes have intense religious or mystical experiences and feelings, leading to a long-standing hypothesis that these areas of the brain could provoke or are involved in religiosity.
In 1970, Kenneth Dewhurt and A.W. Beard tracked sudden religious conversions in temporal lobe epileptics. Of 69 epileptics, they found that 26 of them had "symptoms" of religiosity, though only eight had been religious before their illness. In their paper, Dewhurt and Beard documented six conversion stories of extreme religious encounters correlated with seizures.
One of their patients, "Case 2," was a 35-year-old man born in 1920 who had a history of grand mal seizures. One day, several hours after his episode he "had a sudden dream-like feeling, saw a flash of light, and exclaimed, 'I have seen the light.' He suddenly knew that God was behind the sun and that this knowledge meant power; he could have power from God if he would only ask for it." Multiple visions would follow: A book appeared before him, a world atlas with a torn page, and a pendulum swinging from side to side that would stop when the world came to an end.
Many of their patients had similar revelation stories. An electroencephalogram (EEG) was used to investigate the physiological basis for these events, and in each of the six cases the frontal or temporal lobes showed activation. Though any human experience must show processing in the brain, the idea that profound spiritual moments could be identified, and somehow "explained" by their correlating region, took hold.
In 1997, neuroscientist V.S. Ramachandran saw a patient named Paul whose seizures and religious fixations piqued his interest in "spiritual neuroscience." He wrote about Paul in his book, Phantoms in the Brain.
Ramachandran theorized that religious feelings might be rooted in the limbic system, a complex network in the brain that receives input from the sensory systems and outputs expression of emotion and emotional drive. He thought that maybe this network could be altered—by epilepsy, for example—and change a person's ability to determine what is significant and what is not. If Paul's brain was endowing everything with significance, that's why he was imbuing daily life with religious meaning.
Ramachandran tested two epilepsy patients' Galvanic Skin Response (GSR), which measures the sweat levels on your skin to test if their "salience" pathways were overactive. Your sweat glands are controlled by your autonomic nervous system. If a person is aroused by provocative stimulus, like violent or sexual images, a GSR can pick up the minute changes that happen at skin level.
If Ramachandran's patients showed the same response to all the stimuli he showed them, which included sexual imagery, religious imagery, pictures of family and friends, as well as neutral images—that could explain their intense religiosity. They weren't just hyper-religious, they were hyper-everything. Instead, Ramachandran found that his two epileptic patients showed a heightened response to the religious imagery and a lower-than-normal response to the other stimulating images.
"Their response to the other categories, including the sexual words and images, which ordinarily evoke a powerful response, was strangely diminished compared to what is seen in normal individuals," he wrote. "Thus the results show that there has been no general enhancement of all the connections—indeed, if anything, there has been a decrement. But rather surprisingly, there's been a selective amplification of response to religious words."
Ramachandran ended his experiment with more questions than answers. Did a neural network exist for religion? Was it in the frontal lobes, as previous studies implied? Could you remove the frontal lobe and perform a "Godectomy?" Could a devout atheist become a Catholic, by changing the brain?
In response to the latter question, in 1999, Canadian psychologist Michael Persinger created what the media dubbed the "God Helmet." Persinger applied transcranial magnetic stimulators to parts of his temporal lobe and claimed that the pulses caused him to experience God for the first time.
Journalist Michael Persinger, working for Wired, wrote about him in an article This is Your Brain on God, in which he put on the god helmet himself and waited for a revelation. Though he said he had an out-of-body experience, he saw visions of past memories and old girlfriends, not the divine. It seemed that stimulating the frontal and temporal lobes did something—what that was couldn't be pinpointed exactly.
In 2006, Mario Beauregard and Vincent Paquette put 15 Carmelite nuns in an fMRI and asked them to remember (and attempt to relive) an intense mystical experience. As a control, they asked the nuns to remember an intense moment with another human, and they also scanned them at rest. They too saw activation in many areas of the frontal and temporal lobes, confirming, but not elucidating, previous findings.
Interestingly, they found that when a nun remembered an intense religious moment, it activated a different area than when they remembered an intense moment with another person. Beauregard found this intriguing: Shouldn't the neural systems have been the same, since both were recalling a memory? There was something unique about religious remembrance. But besides being able to show the area of the brain that correlated, they were unable to explain further.
In 2016, Grafman and Cristofori rated 116 brain-damaged veterans on the Mysticism Scale.
Ralph W. Hood created the Mysticism Scale in 1975 so that spiritual experiences and encounters could be measured in some way. The scale asks questions about "unity, sacredness, ineffability, joy, as well as a sense of transcending time and space, and an intuitive belief that the experience is a source of objective truth about reality."
Grafman and Cristofori used this scale to evaluate the Vietnam veterans and then compared the group's lesion locations from CT scans with their self-reported Mysticism Scale information, and found that men with lesions in a certain part of the brain—the frontal and temporal lobes—had higher mysticism scores. Not surprising, based on past work. But they were able to take this information a little further.
"We were so interested in studying mysticism in our patients because most of the fMRI studies cannot really tell you about causality between function and brain activation," Cristofori says. "It's only a true lesion study that you really can respond to the question of causality between function and the brain region involved."
Since most of the lesions are so selective, they could analyze different sub-regions within the frontal and temporal lobes. They found that those specifically with damage to the dorsolateral prefrontal cortex (dlPFC), the region that caps the top of the prefrontal cortex, showed markedly higher mysticism numbers than the healthy controls and even men with lesions in other parts of the brain.
The dlPFC is believed to play an important role in executive functioning, which is essentially the brain's in-house organizer. It is believed to help the brain plan, manage and control memory, reasoning, problem solving, and task completion. (Children who do poorly in school, and have trouble getting organized are now sometimes diagnosed with "poor executive functioning.")
Cristofori says that the Vietnam vets with damage to this area had mysticism scores about double to those with lesions in other areas of the temporal cortex, and almost three times higher than healthy controls. Their sample size decreased to find such specific injuries; even though only five dlPFC-damaged men were compared to eight temporal-lobe injured men, Cristofori still finds their results significant.
The men with dlPFC lesions had similar results to the others on their intelligence tests, both before and after their injuries, except for one: a sorting test. In this exam, the dlPFC patients did worse, since strong executive functioning would be needed to complete it. It would suggest that the same tools needed to sort cards are needed to understand our experiences. Cristofori says that they believe the results show that the dlPFC might have a role in "regulating mysticism." If the part of your brain shuts down that organizes and interprets everyday experiences, those experiences might be perceived as mystical.
"While the temporal lobe has an important role in the generation of the mystical experience itself, the dlPFC has a critical role interpreting and modulating them," she says.
Another study from 2011 also suggested that the "executive theory" plays a big part in religious interpretation. Researchers at the University of Denmark studied 18 Christians who often prayed and 18 secular individuals who had no experience with prayer. They scanned them in an FMRI while playing audio from three different men saying prayers. They were told that one man was a non-Christian, one man was Christian, and the last man was a Christian well known for his "healing powers." Each person was given random assignments for these distinctions; in truth, all the men speaking the prayers were Christian and none had healing powers.
When surveyed after, the Christians consistently reported that they felt God's presence the most when the "Christian healer" was praying, followed by the "Christian", and the least in the "secular" prayer. The non-Christians had a similar hierarchy, but on a much smaller scale and felt God's presence much less.
Comparing the survey results to the brain scans, they found no large neurological changes while the secular group was listening to the prayers. But in the Christian group, there was activity in the dlPFC and surrounding areas while listening to the "secular" prayer, and a deactivation of the dlPFC when listening to the "Christian healer."
Basically, when the Christians listened to the alleged healer, their dlPFC's deactivated. This supports the idea that the executive network is needed to modulate religious experiences, and not just in those with brain damage. On an individual level, even in healthy people, this network can be turned down to allow a person to experience something spiritual and even mystical. Cristofori says the dlPFC is a complex area of the brain that does many more tasks than modulate religious experiences. They suspected that its other functions, or lack thereof, could influence religious belief too. In a new study published this April in Neuropsychologia, they examined the relationships between the vets' injuries not just to religiosity, but fundamentalism—extreme and unwavering religious conviction.
They found that the men with ventromedial prefrontal cortex (vmPFC) lesions, a mid-section of the prefrontal cortex, reported greater fundamentalism, measured through another scale: the Religious Fundamentalism Scale. The fundamentalism scale asks how vets agreed with statements like: "To lead the best, most meaningful life, one must belong to the one, true religion," or: "It is more important to be a good person than to believe in God and the right religion."
The reason for the increased fundamentalism, Cristofori says, is indirect. The dlPFC is also associated with cognitive flexibility, the mental ability to switch between thinking about two different ideas, and "openness": the ability to be open to a variety of different experiences, "intellectually curious, open to emotion, sensitive to beauty and willing to try new things," she says. Damage to that area, and the loss of cognitive flexibility and openness, likely contributed to fundamentalist thinking.
"We should point out that we are not saying that religious or fundamentalist people are neurally impaired," she says. "We would like to emphasize that religious belief is the product of multiple and coordinated functional activities across the brain that merit further study."
Even if it doesn't show the whole picture, a better understanding of religious beliefs such as fundamentalism can inform us about the cognitive and neural basis of other human social and individual belief systems, she says. Both studies combined offer a narrower focus on the specific areas that contribute to belief, and degrees of belief.
But it's worth asking: What do we really learn from which brain region is involved with religion? From the temporal lobes, to zoning in on the dlPFC and vmPFC, are any higher questions answered? Cristofori says that even with a causal link, the study couldn't answer whether mystical experiences are true or false, real or not. I originally suspected that the intention of all this exploration would be to disprove the religious experience as just another impulse of the brain. But the authors, along with many other of the papers from the past, preface their work by stating that what they found has no claim on the validity of religion.
"It is of paramount importance to fully appreciate that elucidating the neural substrates of these experiences does not diminish or depreciate their meaning and value, and that the external reality of "God" can neither be confirmed nor disconfirmed by delineating the neural correlates of religious/spiritual/mystical experiences," Beauregard and Paquette wrote in 2006.
In fact, Ramachandran wrote that some people use the neural basis of the religious experience as proof of God. If there exists a neural network for religion, how did it get there? Did God give it to us? Did he design it?
The desire to use the brain to legitimize or predict human behavior is strong, especially as we get better ways to look at it. But Grafman doesn't see a real-world application of understanding religion in the brain any time soon. Further, asking the brain to determine validity of God might be beside the point, and not the direction he sees his research going in.
"This teaches us about the nature of societies, morality, and evolution," he says. "Interesting questions for the future include things like what is the brain and cognitive basis of conversion, how does the depth of religious knowledge affect how we believe, or how do single issues affect the overall nature of belief. There are many more such questions to answer since these are the kinds of studies that define who we are as humans."
We might never know from the brain if god is "real," but the attempt to understand religious conviction, according to Grafman, is still important enough by itself because of religion's special role in human history.
"The Old Testament bible was the first printed text," he says. "Modern humans continue to have strong forms of religious belief leading to everything from altruism to war. Since religious beliefs are uniquely a human experience, it is important to study them for clues about human evolution, both the past and the future, as well as how our brain develops new regions to perform unique computations and store unique memory representations that make us human."
Grafman says that since god doesn't volunteer for his studies—at least as far as he knows—all he can do is study the human brain when a person engages in religious activities or religious knowledge. Since religion is one of the things that makes humans different from other species, it's critical to keep looking at and studying it, whether or not what they find can answer any larger philosophical questions. The mysteries to potentially be unlocked could be about man himself, not his maker.
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Update 5/2/17: A previous version of this story identified Grafman's affiliation with the Rehabilitation Institute of Chicago; the hospital's name recently changed to the Shirley Ryan AbilityLab.