The goal was to create a brain computer interface (BCI) that could sense in both directions — from the brain to the hand and the hand back to the brain. This constant feedback is important for natural grasping, as we are always interacting with objects of different weights, sizes, and sensitivities — you would not hold a pencil like a piece of paper.
To create the feedback, researchers implanted electrodes into Copeland’s sensory cortex, at regions that are known to normally correlate with signals to and from the hand. Once the electrodes were in place, they began to gently touch the artificial hand and asked a blind-folded Copeland where he felt the pressure.
“I can feel just about every finger — it’s a really weird sensation,” Copeland said following the surgery. “Sometimes it feels electrical and sometimes its pressure, but for the most part, I can tell most of the fingers with definite precision. It feels like my fingers are getting touched or pushed.”
Just four years ago, the University of Pittsburgh achieved another breakthrough in BCIs when researchers built a system that enabled a quadriplegic patient to feed herself using a robot arm. The newest study published in Science Translational Medicine takes that research one step further.
“The most important result in this study is that microstimulation of sensory cortex can elicit natural sensation instead of tingling,” study co-author and member of the University of Pittsburgh Brain Institute, Andrew B. Schwartz, said in a press release. “This stimulation is safe, and the evoked sensations are stable over months. There is still a lot of research that needs to be carried out to better understand the stimulation patterns needed to help patients make better movements.”
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