GIVING LIFE TO LIMBS
In an underground laboratory at the University of Chicago, neuroscientist Sliman Bensmaia peered at a blue computer monitor attached by wires to a Rhesus monkey’s brain.
A lab technician grazed the animal’s finger using a metal probe, and the computer screen erupted in red.
“That’s pretty cool,” said Bansmaia, grinning. “You can see the brain becoming active just by tapping the hand.”
Next, instead of physically tapping the animal’s hand, the technician planned to run a small current of electricity through electrodes in the animal’s brain to simulate the probe. If the animal looked in a certain direction, the scientists would know the “virtual touch” worked.
This research is part of a quest to build a machine that helps humans to feel, providing amputees and quadriplegics with a sense of touch.
Applying electricity to neurons can stimulate cells to help people overcome certain disabilities, as has been shown since the 1960’s by the development of the cochlear implant for hearing.
As hundreds of wounded veterans begin returning home, interest in developing better prosthetics spiked. Scientists at John Hopkins University Applied Physics Laboratory last year completed a new prosthetic arm, which can rotate, twist, and bend in 26 different ways. Scientists also recently outfitted patients with brain electrodes allowing then to move simpler robotic arms with their thoughts.
Without the sense of touch, however, the usefulness of the prostheses is limited.
So last year, John Hopkins gave Bensmaia’s lab about $1.5 million of their federal money to develop even more advanced prostheses that will eventually give the users a simulated sense of touch through the machine’s metal and motors.
The U of C scientists set out to identify and replicate the qualities of touch, including texture, shape, and force, through complex mathematical equations.
Scientists implanted platinum-alloy electrode arrays, each the size of a pencil eraser, into the Rhesus monkey’s brains. The scientists then created neural impulses by emitting small, but focused electrical currents, and recorded the animal’s behavior in response.
After simulating thousands of different touch sensations, Bensmaia and his team hope to map out the way the brain reads those touches. They will then build softwear for the robotic arm’s computerized sensors that will transmit impulses to the electrodes in the human brain, mimicking touch.
Josh Berg, Bensmaia’s study director, took a step back from the testing room and grasped at an apt summary.
“Up here, we are not vision, touch, or smell,” Said Berg, pointing to his heard. “We are all electricity. What we are trying to do is translate information into a language the brain can understand.”
Since 2006, the DARPA, which is part of the Department of Defense, has poured $129 million into its Revolutionizing Prosthetics program.
John Hopkins University and its collaborators expect to implant electrodes in the first human patient this summer. A second patient would get more advanced implants in 2012. and a third patient would get implants in 2013 that may allow him to operate two prosthetic arms using a wireless transmission system.
U of C neuroscientist Nicho Hatsopoulos recently applied to work on the development of that wireless system.
“Where we re right now is basically the beginning stages of the $6 million man,” said Hatsopoulos, standing in his laboratory while a Rhesus monkey moved a cursor around a computer using only his thoughts.
“The ramifications of thought control of actions is a little scary,” Bensmaia said. “It may change the word completely.”
For now, Bensmaia’s focus remains on stimulating neurons and recording the effects. In his lab, Bansmaia leaned over another scientist who is attempting to isolate one neuron out of some 100 billion in the primate’s brain.
The scientist grazed the animal’s finger. In seconds, a thin red line spiked across the computer monitor and a rack of speakers crackled, emitting the amplified sound of a single neuron firing.
“It’s a thing of beauty,” Bensmaia said.