The technique was created by Scuola Internazionale Superiore Di Studi Avanzati (SISSA) in Italy with support from the Universities of Chicago and Cambridge. The research team found when activated with an infrared ray, nanometric photodiodes can send an electrical message to the nerve cell to which they are bound and regulate its function. The stimulation's effects can then be extended and amplified to the surrounding network of neurons (Science Advances, August 12, 2022).

The researchers bound the photodiode to an antibody as the antibody recognizes with great specificity a structure on the surface of the target neuron. The nanometric photodiodes bind to the surface membrane of nerve cells and light up when illuminated with infrared light. The illumination allows researchers to see what role a specific neuron plays in a given process and because infrared is able to penetrate tissue, they can modulate the neuron's activity from the outside in a targeted, noninvasive way.

In this instance, the research team focused on spinal cord sensory neurons involved in pain pathways. They activated an excitatory neuron on the spinal dorsal horn with the photodiode and witnessed an amplification of the pain signal. However, when they activated an inhibitory neuron, the amplification of the pain signal was turned off. Also, by stimulating a target neuron they can modulate the response of the whole circuit.