Rudi Affolter and Gwen Tighe have both experienced strong religious visions. He is an atheist; she a Christian. He thought he had died; she thought she had given birth to Jesus. Both have temporal lobe epilepsy.

Like other forms of epilepsy, the condition causes fitting but it is also associated with religious hallucinations. Research into why people like Rudi and Gwen saw what they did has opened up a whole field of brain science: neurotheology.

The connection between the temporal lobes of the brain and religious feeling has led one Canadian scientist to try stimulating them. (They are near your ears.) 80% of Dr Michael Persinger's experimental subjects report that an artificial magnetic field focused on those brain areas gives them a feeling of 'not being alone'. Some of them describe it as a religious sensation.

His work raises the prospect that we are programmed to believe in god, that faith is a mental ability humans have developed or been given. And temporal lobe epilepsy (TLE) could help unlock the mystery.

Religious leaders

History is full of charismatic religious figures. Could any of them have been epileptics? The visions seen by Bible characters like Moses or Saint Paul are consistent with Rudi's and Gwen's, but there is no way to diagnose TLE in people who lived so long ago.

There are, though, more recent examples, like one of the founders of the Seventh Day Adventist Movement, Ellen White. Born in 1827, she suffered a brain injury aged 9 that totally changed her personality. She also began to have powerful religious visions.

Representatives of the Movement doubt that Ellen White suffered from TLE, saying her injury and visions are inconsistent with the condition, but neurologist Gregory Holmes believes this explains her condition.

Better than sex

The first clinical evidence to link the temporal lobes with religious sensations came from monitoring how TLE patients responded to sets of words. In an experiment where people were shown either neutral words (table), erotic words (sex) or religious words (god), the control group was most excited by the sexually loaded words. This was picked up as a sweat response on the skin. People with temporal lobe epilepsy did not share this apparent sense of priorities. For them, religious words generated the greatest reaction. Sexual words were less exciting than neutral ones.

Make believe

If the abnormal brain activity of TLE patients alters their response to religious concepts, could altering brain patterns artificially do the same for people with no such medical condition? This is the question that Michael Persinger set out to explore, using a wired-up helmet designed to concentrate magnetic fields on the temporal lobes of the wearer.

His subjects were not told the precise purpose of the test; just that the experiment looked into relaxation. 80% of participants reported feeling something when the magnetic fields were applied. Persinger calls one of the common sensations a 'sensed presence', as if someone else is in the room with you, when there is none.

Horizon introduced Dr Persinger to one of Britain's most renowned atheists, Prof Richard Dawkins. He agreed to try his techniques on Dawkins to see if he could give him a moment of religious feeling. During a session that lasted 40 minutes, Dawkins found that the magnetic fields around his temporal lobes affected his breathing and his limbs. He did not find god.

Persinger was not disheartened by Dawkins' immunity to the helmet's magnetic powers. He believes that the sensitivity of our temporal lobes to magnetism varies from person to person. People with TLE may be especially sensitive to magnetic fields; Prof Dawkins is well below average, it seems. It's a concept that clerics like Bishop Stephen Sykes give some credence as well: could there be such a thing as a talent for religion?

Brain imaging

Sykes does, though, see a great difference between a 'sensed presence' and a genuine religious experience. Scientists like Andrew Newberg want to see just what does happen during moments of faith. He worked with Buddhist, Michael Baime, to study the brain during meditation. By injecting radioactive tracers into Michael's bloodstream as he reached the height of a meditative trance, Newberg could use a brain scanner to image the brain at a religious climax.

The bloodflow patterns showed that the temporal lobes were certainly involved but also that the brain's parietal lobes appeared almost completely to shut down. The parietal lobes give us our sense of time and place. Without them, we may lose our sense of self. Adherants to many of the world's faiths regard a sense of personal insignificance and oneness with a deity as something to strive for. Newberg's work suggests a neurological basis for what religion tries to generate.

Religious evolution

If brain function offers insight into how we experience religion, does it say anything about why we do? There is evidence that people with religious faith have longer, healthier lives. This hints at a survival benefit for religious people. Could we have evolved religious belief?

Prof Dawkins (who subscribes to evolution to explain human development) thinks there could be an evolutionary advantage, not to believing in god, but to having a brain with the capacity to believe in god. That such faith exists is a by-product of enhanced intelligence. Prof Ramachandran denies that finding out how the brain reacts to religion negates the value of belief. He feels that brain circuitry like that Persinger and Newberg have identified, could amount to an antenna to make us receptive to god. Bishop Sykes meanwhile, thinks religion has nothing to fear from this neuroscience. Science is about seeking to explain the world around us. For him at least, it can co-exist with faith.

God on the Brain - questions and answers

What are the temporal lobes of the brain?

The temporal lobe controls hearing, speech and memory. The brain has two temporal lobes, one on each side of the brain, located near the ears. The two are interchangeable so if one is damaged the other is usually able to take over the other's function.

What is temporal lobe epilepsy?

It is a condition in which the patient suffers repeated seizures when there is abnormal electrical activity in the temporal lobes of the brain. These seizures may be simple partial seizures without loss of awareness or they can be complex partial seizures with loss of awareness. The patient loses awareness during a complex partial seizure because the seizure spreads to both lobes, causing memory loss. The condition was first recognised in 1881.

What percentage of patients with temporal lobe epilepsy suffer from religious hallucinations?

It is difficult to say because unless the doctor brings up the subject directly with the patient, they may never know if the patient has religious hallucinations. Estimates vary between 10 and 70% , but most neurologists believe only a minority of patients with temporal lobe epilepsy suffer from hallucinations.

Are scientists arguing that all religious experiences can be related to temporal lobe epilepsy?

Not at all. While studies have clearly shown a relationship between religious experience and temporal lobe epilepsy. This does not explain all religious experience by any means. Religious and spiritual experiences are highly complex, involving emotions, thoughts, sensations and behaviours. But scientists do believe that patients with temporal lobe epilepsy, who experience religious hallucinations may provide a valuable model in showing how certain types of religious experience effect the human brain.

Does this work suggest there is a specific 'god spot' in the brain?

Although the temporal lobes are clearly important in religious experience, they are not the whole story. Already the work of Dr Andrew Newberg has shown that a part of the brain called parietal lobes are important. Additionally, very different patterns of brain activity may appear, depending on the particular experience the individual is having. For example, a near death experience might result in different activity patterns from those found in a person who is meditating. Scientists now believe that a number of structures in the brain need to work together to help us experience spirituality and religion.

Are we 'hardwired' for god?

The term 'hardwired' suggests that we were purposefully designed that way. Neuroscience can't answer that question. However what it can say is that the brain does seem to predisposed towards a belief in spiritual and religious matters. The big mystery is how and why this came about.

How does Dr Persinger induce artificially religious experiences in his patients?

Dr Persinger has designed a helmet that produces a very weak rotating magnetic field of between ten nanotesla and one microtesla over the temporal lobes of the brain. This is placed on the subject's head and they are placed in a quiet chamber while blindfolded. So that there is no risk of 'suggestion', the only information that the subjects are given is that they are going in for a relaxation experiment. Neither the subject nor the experimenter carrying out the test has any idea of the true purpose of the experiment. In addition to this, the experiment is also run with the field switched both off and on. This procedure Dr Persinger claims will induce an experience in over 80% of test subjects.

What sort of experiences do subjects report?

This is very dependent on the belief system of the individual subjects. Dr Persinger talks about his subjects feeling a 'sensed presence' - feeling that somebody was in the chamber with them. Subjects who are strongly religious are likely to interpret this presence as god. Whereas, atheists may also report a 'sensed presence' but attribute the phenomena to a trick of brain chemistry, perhaps comparable to when they have taken drugs in the past.

Could it be there is a genetic component to religious belief?

Religious behaviour is so complex it is very unlikely that there will be a single gene for religious activity, but it does seem as if there is some sort of as yet unidentified genetic component. Several studies of identical twins separated at birth and brought up separately have measured religiosity. Religiosity is defined as the intensity of religious belief. These studies have shown that there appears to be about a 50% component to religiosity.

Clearly, what religion you are brought up in is largely dependent upon the culture into which you are born, but what appears to have a significant genetic component is your level of religious intensity.

Will any of this research ever be able to establish whether god exists or not?

Whether god exists or not is something that neuroscience cannot answer. For example, if we take a brain image of a person when they are looking at a picture, we will see various parts of the brain being activated, such as the visual cortex. But the brain image cannot tell us whether or not there is actually a picture 'out there' or whether the person is creating the picture in their own mind. To a certain degree, we all create our own sense of reality. Getting to what is real is the tricky part.

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