Aug 07 2009
New research builds upon the growing body of research into how our brains give us a sense that we are inside our bodies. That is one of the brain’s functions that we take for granted – and do not even realize that it is a function of the brain or that it is necessary – until it is not functioning. When that happens we have an out-of-body experience (OBE).
Prior to modern neuroscience, OBEs were interpreted as mystical or spiritual experiences. In many cultures they were provoked by drugs during spiritual rituals. They have also been reported during certain dream states and in near-death experiences.
Unless one is a neuroscientist or has a keen interest in how the brain works, we tend to think of our mental selves as an integrated whole and not as a collection of independent functions – the latter is more close to the truth. Our brains are more like committees with many different parts carrying out specific functions – some conscious, some unconscious. But since we are our brains we are only aware of the net effect of that part of our brain function that produces our conscious awareness and attention. We are not aware of the bickering committee operating behind the scenes, and therefore we are not aware of all the subconscious tasks being carried out by individual components of our brains.
That is – until one of them stops working. Then we experience a bizarre alteration is our consciousness. There are many interesting examples of this. We can easily understand how if the part of our brain that controls the movement of our left arm is damaged, our left arm becomes paralyzed – we can’t move it. But what happens when the part of the brain that maps the left side of the world is damaged? Then we not only cannot move the left side of our body, we cannot think about the left side of ourselves or the world (a syndrome called “neglect”). Patients with this lesion, usually following a stroke, do not know their left arm is weak, they do not know they have a left arm. If you show them their own left hand they will say that it is yours, or someone else’s. You cannot convince them that it is theirs.
There is another part of the brain that gives us the sense of ownership over the various parts of our bodies (separate from the mapping of the world above). In rare cases after damage this ownership module can lose its input from a paralyzed limb and instead create the illusion of ownership over an imaginary limb (a supernumerary phantom limb). People with this condition feel as if they have an extra limb – they can see it and feel it, and even scratch themselves with it. But of course, they cannot manipulate reality outside themselves with it, because it does not exist except in the crossed wiring in their brains.
And, of course, there are parts of the brain that make us feel as if we are inside our own bodies. This is not an automatic consequence of being our physical selves – our brains have to specifically create the sensation that we exist inside our bodies – that we are placed in three-dimensional space behind our eyes. Our brain gives us an in-body experience, and therefore when this part of the brain is disrupted we have an OBE.
What researchers have been working on are ways to artificially create, at will, an OBE. What they learned is that the creation of an in-body experience is partly based on integrating sensory input – tactile sensation, vestibular sensation (input from the inner ear about orientation to gravity and acceleration), proprioception (sensation of where the body is in three-dimensional space) and visual input. This integration takes place in the temporoparietal junction, especially on the right (non-dominant) side.
Incidentally, this is next to the area of the brain that makes us feel as if we are connected to external reality – so we feel we are in our bodies and our bodies are in the world. Disruption of this function results in what is called “derealization.”
What researcher have learned is that the brain can be tricked by mixing up the tactile and visual input into placing the sense of self somewhere other than where the body is actually located. They have done a series of experiments in which a subject is wearing a virtual reality visor, so that they only see a computer-generated image. This image includes a video of their own back – so there is an image of themselves standing a few feet in front of them. When their back is stroked or otherwise stimulated, the subjects see the virtual self in front of them being stroked at the same time they feel it. Their brains try to integrate these two bits of information – that body in front of me is being stroked and I feel it, therefore I must be inside that body. This is enough to provoke an out-of-body sensation is some subjects (although not a full OBE).
This latest experience is a variation on this same setup. This time subjects are wearing a device on their backs that can both light up and provide a vibration sensation. Subjects can therefore see the lights flashing while feeling the vibration. Sometimes, the lights are in a different area from where the vibration is, and subjects may report that they feel the vibration where they see the lights, rather than where the vibration is actually occurring. Essentially, their brains are being fed contradictory information, and it can be integrated in different ways. Once a “choice” has been made, that is what the subjects experience.
This is similar to visual integration of contradictory or ambiguous visual information – also known as optical illusions. Like the 2-D representation of 3-D objects, your brain can see them one way or another, and often will flip back and forth (like the spinning girl illusion).
In this experiment, subjects who felt the vibration where they saw the lights were more likely to place themselves physically closer to where their virtual self had been, rather than where their bodies were. When the subjects were moved back a few feet and then told to walk up to where they were standing before, those with an out-of-body sensation moved farther up, toward where their virtual self was placed.
This research is fairly well progressed in terms of figuring out what the different parts of the brain are doing to create the in-body and in-reality sensation. However, it is still in its infancy in terms of manipulating this brain function. It is promising, however, that such crude interventions can create such interesting effects.
And of course, we have to speculate about the applications of this technology when it is mature. The same list crops up in most news reports, and I have discussed them here as well. If we can fully manipulate our brains integration of sensory information to create the sensation that we are inside our bodies – we can trick the brain into creating the full sensation that we are inside a virtual representation of ourselves, or an avatar. This means we can feel as if we are inside a virtual game world, that we actually are our avatars – not just watching them on a screen. I have to say – I really hope I eventually see this application.
There are more practical applications as well. This kind of manipulation may be used to make operators of robots feel as if they are the robot, not just operating it, which may significantly enhance control. This would be most important for prosthetic limbs – so when we can give someone a bionic arm they will feel that it is actually their arm, not just a piece of hardware bizarrely attached to their body.
This will all, of course, inevitably lead to the Matrix where people are living virtual lives inside a virtual world. These scientists may be unwittingly doing the basic science research that will later be used by our robot overlords to enslave us inside the Matrix. But I guess that’s a risk we’ll have to take.
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