Injecting Sensation into a Prosthetic Limb

Achievement date: 
2016
Outcome/accomplishment: 

An international team of researchers have stimulated part of a brain’s sensory cortex to create a sense of a hand being touched as the subject watched a rubber hand being stroked. The finding came in work at the Center for Sensorimotor Neural Engineering (CSNE), an NSF-funded Engineering Research Center (ERC) based at the University of Washington (UW), and involved scientists from UW and the Karolinska Institute in Stockholm.

Impact/benefits: 

The insight brings researchers closer to developing prosthetic limbs that a user might actually feel is part of their own body. The researchers tapped into a 64-electrode grid array implanted into the brains of two epilepsy patients to monitor seizures. Positioned over the somatosensory cortex—the region of the brain that processes touch—the arrays enabled the team to focus on the region that corresponded to the subjects’ finger.

Explanation/Background: 

Earlier studies had shown it’s possible to trick the brain into believing that a fake limb is part of the body. In cases where a visible rubber hand was stroked in tandem with a subject’s own hidden hand, participants mistook the prosthetics as part of their own physical self.

For this study, researchers hid a volunteer’s hands behind a screen, and placed a prosthetic hand in front of the screen. Researchers used a touch probe linked to a cortical stimulation device to simultaneously touch the rubber hand with a brushstroke and stimulate the patients’ somatosensory cortex. participants were more likely to agree with the statement “It feels as if the rubber hand were my hand.” Subjects later experienced something called proprioceptive drift—when blindfolded and asked to point to their finger, they tended to point to the rubber hand and not their own.