Do you recall spinning in place as a child? Remember the feeling that you were still turning even after you'd flopped down on the grass? Researchers at the Neurological Sciences Institute at Oregon Health Sciences University now can recreate that sensation so that it can be studied scientifically. Results of a study incorporating the machine, being published in the April 15 edition of the journal Nature, show the brain essentially creates its own version of reality when it receives conflicting information from different senses. The research is a step towards understanding how things go wrong with the extraordinarily complex systems that govern human balance and movement.
The scientists use a device that might not be out of place in an amusement park. A seat is mounted within two frames. The rectangular outer frame tilts backward and forward. The inner frame is mounted to the outer frame so that the seat can be spun around rapidly in addition to being tilted. The research method is straightforward, according to Robert Peterka, Ph.D., associate scientist at the Neurological Sciences Institute and co-author of the article.
"We spin a person for a couple of minutes in pitch darkness, then stop them suddenly. This creates a false sense of rotation. Then we quickly tilt them into a given orientation," said Peterka.
The results are, at least according to some study participants, "confusing, unpleasant and difficult to describe". Subjects who were tilted into a position with their back toward the ground reported they felt like they were lying on their side. And even though they had stopped moving, they felt like they were still rotating and their eyes continued to move as though they were still spinning.
These stomach-wrenching experiments are revealing important information about
the delicate system of fluids and nerves that make up what's called the
vestibulo-ocular reflex. This system is at work when you rotate your head or
move from side to side while
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