Autoscopic Hallucinations


Introduction: Autoscopic hallucinations refers to the phenomena involving out of body experiences, sudden conscious awareness from a viewpoint above or behind the body, or complete loss of self-attribution. From a medical standpoint, most people who experience these types of hallucinations also suffer from somatoparaphrenia, which is a disorder where the individual denies a limb or sometimes a whole side of their body as their own. Generally this results from damage to the right tempoparietal region of the brain. The brain regions that are active during different types of autoscopic hallucinations include the TPJ (tempoparietal junction), occipito parietal lobe, posterior parietal junction (PPJ), the PIVC (para-insular vestibular cortex) and the angular gyrus. The various hallucinations that subjects encounter are OBE's (out of body experience), heautoscopy, room tilt illusions, or the "feeling-of-a illusion". In rare and extreme cases, NDE's (near death experience) occur.
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Functional Anatomy and Causes: It's clear that the regions of the brain involved in inducing these strong experiences are those listed above (TPJ,PPJ,PIVC, etc.) however it is still widely unknown exactly what causes these regions to function abnormally to produce the hallucinations. Physicians who work with patients who report having any of the listed symptoms of autoscopic or heautoscopic hallucinations can induce their symptoms by stimulating these portions of the brain in a controlled environment in order to detect legions, swelling, or other causes which could have damaged the brain.
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(Red area shows location of the left and right angular gyrus)
The stimulation of all these areas (especially the gyrus) induce the same sort of hallucinations that patients previously reported having. In a lot of circumstances, MRI's and fMRI's do not show any sort of damage or abnormalities in the brain which could explain why the patient experienced an OBE. This of course makes these phenomena even more interesting since they are occurring in healthy individuals of all ages with no prior medical histories. Symptoms of these hallucinations vary from person to person, and some experience only one symptoms while others experience multiple. OBE's are the most common and they're often described as "floating above your own body. looking down on yourself lying in bed." Heautoscopy and autoscopy are similar in the sense that they both include the subject seeing themselves from a different vantage point, but autoscopy reveals the subject seeing themselves in front of them without the feeling that they have left their body or current position in space. Heautoscopy is different in that the subject sees themselves from the viewpoint of being in front of their body but they have left their body and are looking at themselves in the position they were in before the experience of leaving the body. Feeling-of-a presence is also seen in patients who suffer from schizophrenia, and they report that a shadowy figure is behind them and that they can "feel" the figure looking at them. When they turn to look, their is no one there, but the feeling still remains. The last occurrence is more common in patients with vertigo, and the brain regions involved are the same for the most part. The subject reports that their landscape view of whatever is in front of them flips 180 degrees. Along with this visual aspect, they also feel very dizzy, obviously, and they often report vertigo.
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What Induces these Hallucinations?
As stated earlier, physicians can stimulate the brain either via electrical current, galvanic, caloric, or sound induced vestibular stimulation. All of these methods prompt the patient to re-experience whatever type of hallucination they reported having. Different hallucinations can trigger more or less activity in one of the senses over another, so by stimulation of the areas of the brain involved, they can determine what pathways are being utilized in each phenomena. For example, an OBE is predominantly a vestibular and auditory expereince and there is very little physical feeling involved. The following chart details this well
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There are also other methods of inducing OBE's and the other forms of hallucinations from a more "recreational" standpoint. Before autoscopy was recognized in the field of neuroscience, many people reported being able to induce such occurrences at will and even benefit from doing so. Astral projection and deep meditation were once looked at as paranormal events, but now science is able to explain what causes people to have such vivid and sometimes spiritual experiences by unlocking these regions of the brain through various methods. Another area of society where such experiences are described is in the drug culture. Very powerful, concentrated, and potent mind altering substances such as lysergic acid-diethylamide-25(LSD) and dimethyltryptamine (DMT) can evoke even stronger OBE's and other hallucinations than just the normal occurrence. A lot of research has gone into what regions of the brain these substances effect to see if they align with the same areas that scientists see light up on fMRI's during autoscopic hallucinations.

Conclusion:
Although many subjects have reported NDE's, OBE's and all the other types of autoscopic hallucinations, there is still much to be learned about their origins and the mechanisms of the brain which evoke the strange phenomenon . Fortunately, with the increase in medical and technological advances the past few decades, there has been a huge increase in knowledge regarding the inner workings of the brain. Hopefully in the future more research will go into determining the underlying causes of autoscopy to ease the suffering of people who experience these often times scary phenomena, although they don't pose a direct threat to the health of an individual, they can greatly affect their psyche.



Sources:

1.)Blanke, O. (2005). Out of body experience, heautoscopy, and autoscopic hallucination of neurological origin. Brain Research Reviews, 50(184), 186.

2.)Murphy, T. (2002). Out of body experience and the angular gyrus of the brain.

3.)Blanke, O. (2007). Body ownership and embodiment: Vestibular and multisensory mechanisms. Clinical Neurophysiology , 38(149), 151-154.

4.)O. Blanke, C. Mohr, C.M. Michel, A. Pascual-Leone, P. Brugger, M.Seeck, G. Thut, Linking out-of body experience to self processing at

the temporo-parietal junction.