By Sheryl James
Feb 11, 2013
Thad Polk, professor of psychology and electrical engineering and computer science, teaches Psychology 121, The Human Mind and Brain. One of the topics studied is "phantom limbs." In this video, Polk demonstrates the phenomenon, showing how the brain can concoct experiences that our senses are not delivering.
Talk about brain power.
At one point during class, students watched a video showing a live, human brain react to a gentle probe during an operation. It was hard not to wince as the brain matter squiggled at each probe.
It also was hard during the same video not to tear up when a young woman who has no legs says, "I can feel myself running and having my muscles contracting all through my legs. ... But it's a dream. I wake up and think, ‘Wow, where are they?' It's like a ghost haunting you; you can feel it, but you can't see it."
Just prior to that, students discussed the relative effects of someone's arm nerves being "ripped out;" how people feel intense pain in limbs that do not exist; how all humans are born with a sense of their whole bodies, even if they are born without some limbs; and the effect human experience has on something called the "neuromatrix." Students didn't quite know what that was at first, only that whatever it was, every person has one.
But probably the most intriguing moment during this class devoted to the study of phantom limbs was when students performed their own experiments. A student extended one arm onto a table. An artificial hand was placed next to it, divided by a partition, so the student could not see the real hand. Another student simultaneously brushed both the real and artificial hands with a paintbrush in an effort to see if the student would start "feeling" the stimulation of the artificial hand.
"I felt sensation in my real hand, but kind of in the other ‘hand'," says Jesse Gold, 19, of Marlboro, N.J. "I was able to convince myself that the fake hand was maybe my real hand, and that I wasn't really sure which was which at the time."
Kate Lambert, 19, from Wixom, Mich., essentially agreed. "After they removed the brushing from the real hand, I still felt it while they were stroking the fake hand just for a few seconds." It was a revealing experience, she added. She did not know people without limbs could experience pain and sensation. "I never knew something like that existed."
You might think this is some kind of pre-med or science class full of juniors and seniors who know their way around medical textbooks, terms and videos showing live brains.
But you would be wrong.
This is Psychology 121, The Human Mind and Brain. It is full of freshmen, and only freshman — 23 in all. The class is part of the freshman seminar series, and every class period brings a new safari into the human brain. Previous classes have focused on savants, autism, mad cow disease, schizophrenia, amnesia, Alzheimer's disease, Tourette's syndrome, and more.
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