Researchers map advanced artificial limbs in the brain

Oct. 27 (UPI) -- Scientists from the Ecole Polytechnique Federale De Lausanne in Switzerland have made a breakthrough in mapping how the brain can control artificial limbs.

The research, published today in the journal Brain, examined how targeted motor and sensor reinnervation, or TMSR, changes the way the brain processes motor control and somatosensory input.

TMSR is a surgical procedure performed on patients who have had amputations of limbs. The TMSR reroutes residual limb nerves to intact muscles and skin to fit them with a limb prosthesis for improved control.

The TMSR system works by transferring residual nerves from the amputated limb to reinnervate and activate new muscle targets, so that when a patient is fitted with a TMSR prosthetic, it sends motor commands to the reinnervated muscles where movement intentions are decoded and sent back to the artificial limb.

Researchers at EPFL used ultra-high field 7 Tesla fMRI to demonstrate how the brain encodes and integrates artificial touch and movements in prosthetic limbs. This method measures brain activity by identifying changes in blood flow.

The team mapped out changes in the cortices of three patients with upper-limb amputations who had TMSR. They found that motor cortex maps of amputated limbs are similar in strength, extent and topography to maps of individuals without amputations but different compared to individuals with amputations who did not have TMSR but used regular prosthetic limbs.

The results show the first neuroimaging study of patients with bionic limbs with TMSR prosthesis.

Researchers were also able to find maps of missing fingers in the somatosensory cortex of TMSR patients, which were activated via reinnervated skin from the residual limb and chest area.