Wi-Fi your brain: revolutionary probe used to wirelessly control neurons
The new tool, described in the journal Cell, is the width of a human hair and was used in the study to determine the path a mouse would walk with the push of a button.
Michael R. Bruchas, associate professor of anaesthesiology and neurobiology at Washington University School of Medicine and a senior author of the study, said: "It unplugs a world of possibilities for scientists to learn how brain circuits work in a more natural setting."
Scientists researching neural circuits often use drugs or optogenetics studies to learn more about their functions. At the moment, the majority of these experiments require injection through a large needle or light delivery through fibre optic cables. These both require surgery that may damage parts of the brain and impose conditions that hinder an animal’s natural movements.
By manufacturing the new optofluidic implant, they have overcome both of these issues. The device is much smaller (80 µm thick and 500 µm wide) than the cannula used for most injections and generally causes less tissue damage. Additionally, the ability to remotely turn on an electric heater or micro LEDs enables programmed control of drug delivery or photostimulation protocols.
Dr James Gnedt, program director at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS), said: “This is the kind of revolutionary tool development that neuroscientists need to map out brain circuit activity.”
To test the device, the researchers delivered the implant to mice with light-sensitive ventral tegmental area (VTA) neurons. By instructing the probe to shine laser pulses on the cells they were able to make the mice stay on one side of the cage. When the laser was activated simultaneously with the release of a drug that blocks neuronal communication, this behaviour stopped.
The device has room for up to four drugs and has four inorganic light-emitting diodes. It is soft, like brain tissue, and can remain in the brain for a long time without causing inflammation or tissue damage. Instructions for manufacturing the device are included in the paper.
“In the future, it should be possible to manufacture therapeutic drugs that could be activated with light,” says Dr Bruchas. “With one of these tiny devices implanted, we could theoretically deliver a drug to a specific brain region and activate that drug with light as needed. This approach potentially could deliver therapies that are much more targeted but have fewer side effects.”
Jeong JW, McCall JG, Shin G, Zhang Y, Al-Hasani R, Kim M, Li S, Sim JY, Jang KI, Shi Y, Hong DY, Liu Y, Schmitz GP, Xia L, He Z, Gamble P, Ray WZ, Huang Y, Bruchas MR, Rogers JA Wireless Optofluidic Systems for Programmable In Vivo Pharmacology and Optogenetics Cell (2015) doi: 10.1016/j.cell.2015.06.058