Artificial neurons on silicon chips that precisely mimic real, living nerve cells responding to a range of stimulations have been designed by a team of scientists supported by the EU-funded CResPace project.

With its promise to bring new insights into the diagnosis and treatment of conditions as varied as cancer, cardiovascular and neurodegenerative diseases, bioelectronic medicine is now in the spotlight. Bringing together various fields like biochemistry, molecular medicine, neuroscience, immunology, electrical and mechanical engineering, computer science and mathematics, bioelectronic medicine focuses on electrical signaling in the nervous system.

Researchers in this field are already using such information to create biomedical devices delving into complicated neural networks. However, developing artificial neurons has been difficult due to the challenges of complex biology and hard-to-predict neuronal responses.

Solid-state Neurons

Importantly, the artificial neurons not only behave just like biological neurons but only need one billionth the power of a microprocessor. This makes them perfectly suited for use in medical implants and other bio-electronic devices.

The CResPace (Adaptive Bio-electronics for Chronic Cardiorespiratory Disease) project that supported the study is scheduled to end in December 2021. A key application of the technology developed by the project involves adaptive cardiac resynchronization that relies on small neural networks known as central pattern generators (CPGs).

These neuronal circuits control several functions like respiration and heartbeat, and the coordination between muscles responsible for swallowing. The project implements CPGs with physical hardware to replicate natural control of heart rate and resynchronize heart chambers.

“Artificial neurons could repair diseased biocircuits by replicating their healthy function and responding adequately to biological feedback to restore bodily function. In heart failure for example, neurons in the base of the brain do not respond properly to nervous system feedback, they in turn do not send the right signals to the heart, which then does not pump as hard as it should,"

according to project coordinator University of Bath.

Nonlinear Response

The University highlighted the challenges involved with creating artificial neurons and explains how the scientists have overcome these.

“The researchers successfully modeled and derived equations to explain how neurons respond to electrical stimuli from other nerves. This is incredibly complicated as responses are ‘nonlinear’ — in other words if a signal becomes twice as strong it shouldn’t necessarily elicit twice as big a reaction — it might be thrice bigger or something else."

The approach combines several breakthroughs, which open new horizons to neuromorphic engineering from programming analogue computers to soft bioimplants.

“Our work is paradigm changing because it provides a robust method to reproduce the electrical properties of real neurons in minute detail. We are developing smart pacemakers that won’t just stimulate the heart to pump at a steady rate but use these neurons to respond in real time to demands placed on the heart—which is what happens naturally in a healthy heart. Other possible applications could be in the treatment of conditions like Alzheimer’s and neuronal degenerative diseases more generally,"

said lead author Prof. Alain Nogaret.

The work was supported by the European Union’s Horizon 2020 Future Emerging Technologies Programme.

[1] Abu-Hassan, K., Taylor, J.D., Morris, P.G. et al. Optimal solid state neurons. Nat Commun 10, 5309 (2019).

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