Written by LW user Kaj_Sotala.
This is part of LessWrong for EA, a LessWrong repost & low-commitment discussion group (inspired by this comment). Each week I will revive a highly upvoted, EA-relevant post from the LessWrong Archives, more or less at random
Excerpt from the post:
1. The Consciousness Researcher and Out-Of-Body Experiences
In his book Consciousness and the Brain, cognitive neuroscientist Stansilas Dehaene writes about scientifically investigating people’s reports of their out-of-body experiences:
… the Swiss neurologist Olaf Blanke[ did a] beautiful series of experiments on out-of-body experiences. Surgery patients occasionally report leaving their bodies during anesthesia. They describe an irrepressible feeling of hovering at the ceiling and even looking down at their inert body from up there. [...]
What kind of brain representation, Blanke asked, underlies our adoption of a specific point of view on the external world? How does the brain assess the body’s location? After investigating many neurological and surgery patients, Blanke discovered that a cortical region in the right temporoparietal junction, when impaired or electrically perturbed, repeatedly caused a sensation of out-of-body transportation. This region is situated in a high-level zone where multiple signals converge: those arising from vision; from the somatosensory and kinesthetic systems (our brain’s map of bodily touch, muscular, and action signals); and from the vestibular system (the biological inertial platform, located in our inner ear, which monitors our head movements). By piecing together these various clues, the brain generates an integrated representation of the body’s location relative to its environment. However, this process can go awry if the signals disagree or become ambiguous as a result of brain damage. Out-of-body flight “really” happens, then—it is a real physical event, but only in the patient’s brain and, as a result, in his subjective experience. The out-of-body state is, by and large, an exacerbated form of the dizziness that we all experience when our vision disagrees with our vestibular system, as on a rocking boat.
Blanke went on to show that any human can leave her body: he created just the right amount of stimulation, via synchronized but delocalized visual and touch signals, to elicit an out-of-body experience in the normal brain. Using a clever robot, he even managed to re-create the illusion in a magnetic resonance imager. And while the scanned person experienced the illusion, her brain lit up in the temporoparietal junction—very close to where the patient’s lesions were located.
We still do not know exactly how this region works to generate a feeling of self-location. Still, the amazing story of how the out-of-body state moved from parapsychological curiosity to mainstream neuroscience gives a message of hope. Even outlandish subjective phenomena can be traced back to their neural origins. The key is to treat such introspections with just the right amount of seriousness. They do not give direct insights into our brain’s inner mechanisms; rather, they constitute the raw material on which a solid science of consciousness can be properly founded.
The naive hypotheses that out-of-body experiences represented the spirit genuinely leaving the body, were incorrect. But they were still pointing to a real observation, namely that there are conditions which create a subjective experience of leaving the body. That observation could then be investigated through scientific means. (Full Post on LW)
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