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Researchers identify brain activity related to phantom limbs
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While not technically strange weekend news, the concept of phantom limbs has always been a bit weird to me. As someone who has only ever experienced phantom cell phone rings (and been thoroughly creeped out by them), the idea of experiencing the feeling of an entire limb that is no longer in existence causes a good case of what my mother refers to as "The Whams" (an upgrade from the willies).
Phantom limbs are not restricted to amputations. Some stroke victims who suffered paralysis of one half of the body also confide that they feel movement associated with their immobile limbs. And it is not restricted to merely feeling the presence of the limb. "In some unusual cases…patients have reported seeing their phantom limb or feeling objects or body parts with it, which indicates that multiple areas of the brain may be involved in SPLs [supernumerary phantom limb]." [EurekAlert]
Researchers in Switzerland think they had identified the regions of the brain responsible for creating phantom limbs and the senses that go along with them. Scientists studied a stroke victim who claimed that the phantom limb of her now-paralyzed left arm could do a number of things a normal limb could do, including "scratch an itch on her head, with an actual sense of relief." [EurekAlert] fMRI was used to observe the woman using and imagining to use her functional right hand, imagining using her paralyzed left hand, and imagining to use her SPL.
What they found was that actual movement of her right hand stimulated "dominant activation of left areas of the brain associated with movement, perception of stimuli and visual processing, as expected." [EurekAlert] Imagining to move her functional hand also caused weaker activation of the same areas. Imagining to move her paralyzed left hand had a similar response, though this time it was the right side of the brain that was activated.
Where it got interesting was the imagined movements of the SPL: "When asked to scratch her cheek with the SPL, areas of the brain associated with movement and vision were activated, which confirmed her report that she could see and move her SPL. In addition, a measurable sensory response was also detected when she scratched her left cheek with the SPL." [EurekAlert].
Scientists think that SPL activation of the brain may be due to the fact that the brain hasn't coped with the lack of sensory input due to paralysis. For a lifetime, the brain has been controlling said limb, and its sudden disappearance is difficult to process. So the imagined movements of SPL could be something along the lines of a coping mechanism. There is also some thought that such strange brain activity may actually be the underlying cause of so-called out of body experiences (autoscopic phenomena).
It does not appear that the phantom limbs caused by amputation were investigated, but it is likely only a matter of time before similar results surface. After all, as the study concluded "Ultimately…these conditions might offer a unique way to understand how the brain constructs a normal experience of bodily awareness and the self." [EurekAlert]
The study was led by Asaid Khateb of Geneva University Hospitals and was published in a recent issue of Annals of Neurology.
More strange weekend news: Scientists investigate critter contraceptives * Couple clones dog for $155,000 * The great space illusions
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