Ghosts in the machine

March 8th, 2016 Brain World, Features

Spirits moaning in castle keeps and dragging chains across dusty attics might all be in our minds after all, as Drew Turney learns.

Since time immemorial, we’ve been seeing ghosts.

Whether it’s a disembodied voice whispering in the night, the classic lady in white drifting through walls or even a candle flickering in a room with a closed window, art and culture have made them as familiar to us as they are to the mystics and psychics who supposedly experience them.

Maybe the reason they’ve become so indelible on the collective psyche is because they represent so much – a warning, the presence of a departed loved one, associations with horror and fear, the afterlife. With a developed, self-aware mind that’s evolved to pursue and attribute meaning, it’s no wonder we’ve loaded ghosts with millennia of spiritual and/or religious overtones.

On the surface, ghosts and spirits don’t seem to have much to do with phantom limb syndrome, but recent research suggests a strong link. The clue might be in the name – where phantom limb refers to a body part that doesn’t exist, projected into the world by our consciousness, might a phantom self, body or third party we perceive as a ghost be similarly all in the mind?

When the mind forgets the body

Our journey starts with a mental construct called the body schema – your constant, unconscious narrative about your body’s relationships to everything around it. Sound and vision, gravity, your nervous system’s response to the environment, the tiny channels of liquid in your ears that tell you you’re upright and countless other physical properties combine to give us what feels like an unshakable sense of where we are in relation to the world and everything in it.

But changes in neurology caused by anything from brain lesions to extreme emotional states can make our body schema go wrong with surprising (and scary) ease. “Disruption of our networks’ patterns of activity can create sensations of being separated from your own body, perceiving the body from ‘outside’ and shifts in perception of place and time,” says neuroscientist and neuroethicist Dr James Giordano, Professor of Neurology at Georgetown University Medical Center, Washington DC.

Simple manifestations of such phenomena might be a feeling of déjà vu or the lesser known jamais vu, where we experience something we recognise but which still seems unfamiliar.

So researchers wondered if we might bring ghost sightings – or similar experiences – about by taking experiments that have successfully treated people with body schema problems (such as those who experience pain or discomfort in a body part that doesn’t exist anymore) and going a step further.

In order to generate a whole-of-body illusion, scientists at École Polytechnique Fédérale in Lausanne, Switzerland, put VR goggles on subjects standing in an empty room. An image of themselves standing six feet ahead was projected into the goggles, and their backs were stroked with a pointed stick at the same time they saw their virtual self being touched at the same time.

When the real and virtual touching was synchronized, the subjects reported the sensation of being momentarily in the projected body. A similar experiment using a mannequin dressed in identical outfits as the subjects resulted in the sense of self being projected into the mannequin.

Subsequent experiments by a neuroscientist from the Karolinska Institute, Sweden while visiting University College London, involved projecting an image of subjects into video goggles from two camera placed 6 feet behind them. Using similar touching patterns to those described above, the subjects felt they were looking at their own bodies from six feet away, their corporeal self disconnected from their physical body.

The decoupled mind

But what does this tell us about seeing ghosts? As Peter Brugger, a neuroscientist with University Hospital Zurich told ABCnews; ‘Normal brains can easily be duped about the source of an action at a distance, that they themselves have the agency over actions.’

There’s also a direct terminological leap from phantom limb to bigger body schema concepts that could incorporate ghosts. “Phantom limb was frequently described as ‘ghost limb’,” Brugger tells Brain World. “The term ‘phantom body’ was in fact introduced to depict ghostly phenomena as phantom limb-style phenomena.

“The difficulty is that you’re never ‘amputated’ from the whole body, but there are neurological diseases in which such an ‘amputation’ occurs at the highest level of body representation. The consequence is a split between the physical body and its representation, giving rise to many doppelgänger [other self] and ghost phenomena.”

Such phenomenon can arise when the localization of your body in space no longer matches the physical body but is projected somewhere. “The experience of a doppelgänger has been the most thoroughly and convincingly studied in the ‘projection of body schema’ context,” he says.

Giordano adds that because we’re such spiritual/emotional animals, we often interpret such phenomena through such a lens. “These [phenomena] can assume spiritually emotional content or be interpreted as ‘supernatural’ for some people,” he says. “It’s not unusual for people grieving to report they’ve heard or even seen a loved one who’s recently died while falling asleep or drifting out of sleep.”

We’re also not limited to a single projected body schema just because we’re limited to one physical body. Brugger reminds us that ghosts are sometimes experienced as more than just one single entity with its own agency. If a haunted house contains a piercing scream, footsteps making their way along a dark hallway or a skeletal figure draped in rags limping across the grounds, it could be a multiplication of the body schema – just like multiple voices tormenting a schizophrenia sufferer all belong to him or herself.

Related phenomena

The list of supposedly paranormal activity a skewed sense of body awareness might help explain is helpfully long. Many people claim to have experienced psychography (usually called automatic writing), where they claim a disembodied entity or intelligence from beyond the physical world takes control of their hand to write messages to the living. Maybe it’s indeed the subject doing the writing but projecting the body schema of their hand, arm and the content of what they’re writing elsewhere.

Peter Brugger interviewed accomplished mountaineers, many of whom had climbed to altitudes of 27,000 feet and reported presences, sometimes full out of body experiences. The common thread was that they’d all made their climbs to such heights without supplementary oxygen, and hypoxia (a shortage of oxygen) is just the kind of radical shift in brain physiology that can turn the body schema on its head.

A third party speaking from beyond the body is a widely documented part of schizophrenia, and it might simply be the audio version of phantom limb and other body schema projections. When it comes to the mind’s motor control, simply thinking a thought is enough to make it seem the sufferer is ‘hearing’ it voiced by a separate entity with its own agency.

That’s further evidenced by the fact that if you can observe a schizophrenic while he or she is hearing voices, their larynx moves as they subvocalize the thought they’re attributing elsewhere. Today scientists also know that brain areas associated with motor speech production are activated when a schizophrenic hears voices.

It’s not the only giveaway the body reveals. As long as you’re in your right mind it’s impossible to tickle yourself, but as you might expect, people with body schemas projecting elsewhere can do so as if a real other person is doing the tickling.

It’s also pretty common for people to report floating in the air above and looking down on themselves after a sudden and severe injury, during sleep paralysis, after particularly demanding sports or during intensive meditation – all phenomena that can cause spikes or troughs in levels of oxygen, blood sugar or neurochemicals.

Why we see ghosts

The reasons we might see spirits because of brain states are as varied as the brain states we can experience, everything from trauma to fatigue. James Giordano explains how some cases of temporal lobe epilepsy result in symptoms that are construed or perceived as spiritual or religious. “They can include bodily sensations like smells, feelings of lightness or the presence of another being and heightened emotions,” he says, “sometimes to the point of rapture.”

As we’ve already seen, schizophrenia and other psychotic disorders are prime targets for perception of the paranormal – although curiously, auditory and tactile hallucinations are more common under most conditions. Visual hallucinations are more associated with drug-induced states, as many recreational and medical users can attest.

There’s also a common religious or spiritual dimension felt by sufferers of delusory disorder, a psychiatric condition associated with non-bizarre delusions of thinking. According to a 2010 study, religious delusions are generally less troublesome to the sufferer than other types like hypochondria or paranoia and can be associated with delusions of grandeur. Might that help explain why we think a deceased relative goes to the extraordinary steps of making contact from beyond the grave to impart some serious message?

As Giordano explains, there’s a common neurological thread to such disorders. “It appears to involve loss of network integration between the brain pathways that parse imagined thoughts and stream of consciousness from the experience of events out in the external environment.”

But as we’ve already seen, far more common occurrences can prime the brain to hallucinate ghosts and goblins like profound fatigue or dehydration, even being in a hypnogogic or hypnopompic state (the scary-sounding scientific terms for falling asleep or waking up).

There are even cases where extremes of emotion can result in ghostly visitations. “It’s somewhat rare,” Giordano begins, “but sudden and intense emotion can alter patterns of activity in neural networks that integrate sensory and emotional processes. That can then cause disconnection, de-realization or other altered sensory perception. It might produce a feeling of being ‘detached’ or ‘removed’ from your body, hearing voices or experiencing the presence of another person.

In fact, emotions might help explain another commonality to ghosts sightings. Along with the fact that they’re often visually unclear, many witnesses reporting particular feelings associated with them.

When parietal lobe lesions are involved, Peter Brugger wonders if it might help explain the appearances of ghosts as pale, transparent, milky, colorless, etc. “Ghosts are often at the verge of vision,” he says. “The parietal lobe is responsible for the spatial extension of a body, localization of your ‘felt’ presence in space.

“In the convergence zones between the parietal and occipital lobes, things are visualized incompletely and appear misty. The color gray is very frequently mentioned. If the irritation was wholly in the occipital lobe things would be more naturally colored like a typical visual hallucination.”

Eliciting extreme emotion in test subjects – ethics notwithstanding – is probably the easiest way to replicate such conditions for experimentation, but as Brugger adds, explaining ghosts is just one item on a very long list of things we might explain when we know how to untangle emotional response from neural circuitry.

“There are a lot of effects emotions have on cognitive processing that we don’t understand,” he says. “A tentative answer might be that emotions are mediated by – among other regions – the limbic system, which is widely linked throughout the brain, especially to centers that mediate bodily experience.”

For now we might have to rely on methods that – however advanced – are still crude because of our limited understanding about how the brain works. Giovanni Berlucchi of the University of Verona and Salvatore Aglioti of the University of Rome published research in 1999 about how electrical stimulation (similar to transcranial magnetic stimulation – TMS) of the insula caused the illusion of changes in one’s body position and the feeling of being outside the body.

Neuroscience has advanced a long way in the subsequent 16 years, but as long as things still go bump in the night and we hide under the covers instead of switching on some brain-wave scanner to reset and reorient our body schema by artificial means, we have a long way to go.


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