Researchers Learn the Language of the Nervous System

Zurich – Zurich researchers and an international team have discovered that neuroprostheses communicate better with the brain via natural signals than the rigid stimulation of the sciatic nerve used to date. This provides greater safety for wearers of prosthetic legs, for example.

Together with colleagues from Germany, Serbia and Russia, researchers at the Swiss Federal Institute of Technology in Zurich (ETH) have succeeded in modifying the signals emitted by neuroprostheses so that they resemble those of the missing body part. According to a recently published study, the results of this neuroscientific technology inspired by the human body could "provide a model for the development of novel assistive neurotechnologies". This would be relevant for arm and leg prostheses, for example, but also for spinal implants or electrodes for brain stimulation.

A few years ago, the research team led by Stanisa Raspopovic from the ETH Neuroengineering Lab developed leg prostheses that allowed amputees to feel the replacement body part for the first time. Her neuroprostheses were connected to the sciatic nerve in the femoral stump by means of implanted electrodes. However, they were "not yet able to create a natural feeling", explains Raspopovic in a report by ETH.

He and his team therefore relied on biomimetic stimulation, i.e. natural signals that are able to "write back" physiologically plausible information to the rest of the healthy nervous system. Doctoral student Natalija Katic developed a computer model called FootSim for this purpose. It is based on data from a Canadian study in which the activity of so-called mechanoreceptors in the soles of the feet of healthy test subjects was recorded.

This data was "translated" into biomimetic impulses. The researchers proved that biomimetic stimulation is superior to rigid stimulation and puts less strain on the brain, first in cat experiments and then in a clinical study with leg amputees. ce/mm

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