How the brain creates out-of-body experiences and religious epiphanies
There are many carefully documented accounts in the medical literature of intense, life-altering religious experience in epileptic seizures. Hallucinations of overwhelming intensity, sometimes accompanied by a sense of bliss and a strong feeling of the numinous, can occur especially with the so-called "ecstatic" seizures that may occur in temporal lobe epilepsy. Though such seizures may be brief, they can lead to a fundamental reorientation, a metanoia, in one's life. Fyodor Dostoevsky was prone to such seizures and described many of them, including this:
The air was filled with a big noise and I tried to move. I felt the heaven was going down upon the earth and that it engulfed me. I have really touched God. He came into me myself, yes God exists, I cried, and I don't remember anything else. You all, healthy people ... can't imagine the happiness which we epileptics feel during the second before our fit. ... I don't know if this felicity lasts for seconds, hours or months, but believe me, for all the joys that life may bring, I would not exchange this one.
A century later, Kenneth Dewhurst and A. W. Beard published a detailed report in the Journal of Neurology, Neurosurgery, and Psychiatry of a bus conductor who had a sudden feeling of elation while collecting fares. They wrote:
He was suddenly overcome with a feeling of bliss. He felt he was literally in Heaven. He collected the fares correctly, telling his passengers at the same time how pleased he was to be in Heaven. ... He remained in this state of exaltation, hearing divine and angelic voices, for two days. Afterwards he was able to recall these experiences and he continued to believe in their validity. [Three years later] following three seizures on three successive days, he became elated again. He stated that his mind had "cleared." ... During this episode he lost his faith.
He now no longer believed in heaven and hell, in an afterlife, or in the divinity of Christ. This second conversion -- to atheism -- carried the same excitement and revelatory quality as the original religious conversion.
More recently, Orrin Devinsky and his colleagues have been able to make video EEG recordings in patients who are having such seizures, and have observed an exact synchronization of the epiphany with a spike in epileptic activity in the temporal lobes (more commonly the right temporal lobe).
"I was flying forwards, bewildered. I looked around. I saw my own body on the ground. I said to myself, 'Oh shit, I'm dead.'"
Ecstatic seizures are rare -- they only occur in something like 1 or 2 percent of patients with temporal lobe epilepsy. But the last half century has seen an enormous increase in the prevalence of other states sometimes permeated by religious joy and awe, "heavenly" visions and voices, and, not infrequently, religious conversion or metanoia. Among these are out-of-body experiences (OBEs), which are more common now that more patients can be brought back to life from serious cardiac arrests and the like -- and much more elaborate and numinous experiences called near-death experiences (NDEs).
Both OBEs and NDEs, which occur in waking but often profoundly altered states of consciousness, cause hallucinations so vivid and compelling that those who experience them may deny the term hallucination, and insist on their reality. And the fact that there are marked similarities in individual descriptions is taken by some to indicate their objective "reality."
But the fundamental reason that hallucinations -- whatever their cause or modality -- seem so real is that they deploy the very same systems in the brain that actual perceptions do. When one hallucinates voices, the auditory pathways are activated; when one hallucinates a face, the fusiform face area, normally used to perceive and identify faces in the environment, is stimulated.
In OBEs, subjects feel that they have left their bodies -- they seem to be floating in midair, or in a corner of the room, looking down on their vacated bodies from a distance. The experience may be felt as blissful, terrifying, or neutral. But its extraordinary nature -- the apparent separation of "spirit" from body, imprints it indelibly on the mind and may be taken by some people as evidence of an immaterial soul -- proof that consciousness, personality, and identity can exist independently of the body and even survive bodily death.
Neurologically, OBEs are a form of bodily illusion arising from a temporary dissociation of visual and proprioceptive representations -- normally these are coordinated, so that one views the world, including one's body, from the perspective of one's own eyes, one's head. OBEs, as Henrik Ehrsson and his fellow researchers in Stockholm have elegantly shown, can be produced experimentally, by using simple equipment -- video goggles, mannequins, rubber arms, etc. -- to confuse one's visual input and one's proprioceptive input and create an uncanny sense of disembodiedness.
Hallucinations, whether revelatory or banal, are not of supernatural origin; they are part of the normal range of human consciousness and experience.
A number of medical conditions can lead to OBEs -- cardiac arrest or arrhythmias, or a sudden lowering of blood pressure or blood sugar, often combined with anxiety or illness. I know of some patients who have experienced OBEs during difficult childbirths, and others who have had them in association with narcolepsy or sleep paralysis. Fighter pilots subjected to high G-forces in flight (or sometimes in training centrifuges) have reported OBEs as well as much more elaborate states of consciousness that resemble the near-death experience.