May 25, 2024

Harnessing Nature: Creating Neuroprosthetics that Speak the Brain’s Language

A team of researchers at the ETH Zurich Neuroengineering Lab, led by Professor Stanisa Raspopovic, made headlines a few years ago for their groundbreaking work in developing neuroprosthetic legs that allowed amputees to experience sensations from their artificial limbs. Unlike conventional prosthetic legs that only offer stability and support, the team’s prosthetic device was connected to the sciatic nerve in the patients’ thighs using implanted electrodes.

This direct electrical connection enabled the neuroprosthesis to communicate with the brain, providing real-time feedback on pressure changes detected on the sole of the prosthetic foot during walking. This innovative approach not only increased the users’ confidence in their prostheses but also significantly improved their mobility on various terrains.

Professor Raspopovic highlighted the limitations of current neuroprosthetics, which often induce artificial and unpleasant sensations due to the use of time-constant electrical pulses to stimulate the nervous system. In a recent study published in Nature Communications, Raspopovic and his team emphasized the importance of adopting naturally inspired, biomimetic stimulation to enhance the effectiveness of neuroprosthetics.

To create these biomimetic signals, doctoral student Natalija Katic developed a computational model called FootSim based on data from natural mechanoreceptors in the foot. The model accurately simulates the behavior of mechanoreceptors during different stages of walking, generating neural signals that mimic the natural feedback loop between the foot and the brain.

Collaborating with researchers in Germany, Serbia, and Russia, the team conducted experiments with cats to validate the effectiveness of biomimetic stimulation. By comparing the neural responses to biomimetic signals and conventional time-constant stimulation, the researchers observed that biomimetic signals closely mirrored the natural neural patterns, while traditional stimulation led to information overload in the spinal cord.

The clinical trial with leg amputees further confirmed the superiority of biomimetic stimulation, showing improved mobility and cognitive performance compared to time-constant stimulation. The ability of subjects to climb stairs faster and complete complex tasks with greater accuracy highlighted the advantages of biomimetic neurostimulation in enhancing prosthetic functionality and user experience.

Professor Raspopovic emphasized the broader implications of their findings beyond limb prostheses, suggesting that biomimetic signals could revolutionize various neural implants and devices, including spinal implants and brain electrodes. By understanding and speaking the language of the nervous system, researchers aim to develop neuroprosthetics that can truly communicate with the brain in a natural and intuitive manner.

The pioneering work of Professor Raspopovic and his team represents a significant step towards the development of advanced neuroprosthetics that not only restore motor function but also ensure a more seamless integration with the human nervous system. As the field continues to evolve, biomimetic stimulation holds the promise of transforming the lives of individuals with limb loss and neurological disorders, offering new possibilities for enhanced mobility and sensory feedback.

1. Source: Coherent Market Insights, Public sources, Desk research
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