Scientists have built tiny silicon microchips, small enough to fit on a fingertip, which are "nearly identical" to biological nerve cells present in the human body. The research team suggests the low-power cells-on-a-chip could be used in bio-electronic devices and implants, providing a new way to combat diseases affecting the nervous system, such as Alzheimer's, or spinal cord injury.
Nerve cells, or neurons, are present throughout the brain and the nervous system and rapidly send electrical signals through their long, spindly arms, relaying information from brain to body and back. Their signalling activities require ion channels that convert mechanical or chemical signals into electrical ones. It's a complex dance underlying all our nerve impulses -- but that complexity has made it difficult to unravel how cells respond to certain stimuli.
"Until now neurons have been like black boxes, but we have managed to open the black box and peer inside," said Alain Nogaret, a physicist at the University of Bath and co-author of the study, in a press release. "Our work is paradigm changing because it provides a robust method to reproduce the electrical properties of real neurons in minute detail."
The new study, published in the journal Nature Communications on Tuesday, details the breakthrough technology which reproduces the electrical properties of a neuron on the tiny chip. The team were able to replicate the dynamics of individual nerve cells in the brain required for memory ("hippocampal neurons") and those required for breathing ("respiratory neurons"). The chips have a number of synthetic ion channels, which are responsible for the electrical impulses in biological cells.
Comparing the signals to those found in rat hippocampal neurons and rat brain stem neurons, the research team subjected their chip to 60 different stimulation protocols and modeled the responses, finding each time the chip was able to recapitulate responses seen in real cells.
While the study shows promise for potential bio-medical implants in the future, the authors note that other features of nerve cells will need to be considered.
The chip acts like a single cell, but nerve cells are complex beasts with branching arms, known as dendrites, responsible for propagating signals from cell to cell. The team suggests their model allows for the "complete dynamics of a biological neuron" to be placed on the chip, while noting a second compartment may need to be added that could describe the active properties of dendrites.