Artificial neurons can behave like real ones

Researchers successfully create them on tiny silicon chips.

The authors of a study in Nature Communications exhibit the kind of calm rationality that makes one believe. They point out that neuromorphic silicon devices replicating biological nerve functions have been proposed before, but problems have hampered attempts to develop them.

The design of devices such as silicon neurons, synapses and brain-inspired networks is not meant to copy the behaviour of biological cells, they say, but to search for the organising principles of biology that can be applied to practical devices.

However, an increasing focus on implantable bioelectronics to treat chronic disease is changing this paradigm and “instilling new urgency in the need for lowpower analogue solid-state devices that accurately mimic biocircuits”.

The British/swiss/new Zealand team’s paper describes a way of making silicon chips that are smaller than a fingertip but reproduce the electrical behaviour of biological neurons. This, they say, could lead to the development of bionic chips to repair biological circuits in the nervous system when functions are damaged or lost to disease.

They designed microcircuits modelling ion channels that integrate raw nervous stimuli and respond in a similar way to biological neurons, then recreated the activity of individual hippocampal and respiratory neurons in silicon chips.

In a series of 60 electrical stimulation protocols, they found that the solidstate neurons produced nearly identical electrical responses when compared to biological neurons.

“We can very accurately estimate the precise parameters that control any neurons behaviour with high certainty,” says Alain Nogaret, from the University of Bath. “We have created physical models of the hardware and demonstrated its ability to successfully mimic the behaviour of real living neurons.

“Our third breakthrough is the versatility of our model, which allows for the inclusion of different types and functions of a range of complex mammalian neurons.”

Nogaret and colleagues note that respiratory neurons, such as those they have modelled, couple respiratory and cardiac rhythms and are responsible for respiratory sinus arrhythmia.

Loss of this coupling through age or disease is a prognosis for sleep apnoea and heart failure. They suggest that a device that adapts biofeedback in the same way as respiratory neurons may offer a potential therapy in the future.