Wireless Probe Enables Brain Control With Optogenetics

With a press of a button, scientists can wirelessly determine the path a mouse walks, a new study shows. The remote controlled, next-generation tissue implant, developed by researchers at the Washington University School of Medicine, St. Louis, and University of Illinois, Urbana-Champaign, enables neuroscientists to inject drugs and shine lights on neurons deep inside the brains of mice.

Senior author Michael R. Bruchas, Ph.D., associate professor of anesthesiology and neurobiology at Washington University School of Medicine, said:

“It unplugs a world of possibilities for scientists to learn how brain circuits work in a more natural setting."

Bruchas’ lab studies circuits that control a variety of disorders including addiction, depression, stress, and pain.

Scientists who study these circuits typically have to choose between injecting drugs through bulky metal tubes and delivering lights through fiber optic cables. Both options necessitate surgery which can damage parts of the brain and introduce conditions that hinder animals’ natural movements.

Remote Optofluidic Implant

The new device is made out of soft materials that are a tenth the diameter of a human hair and can simultaneously deliver drugs and lights. Jae-Woong Jeong, Ph.D., a bioengineer formerly at the University of Illinois at Urbana-Champaign, worked with Jordan G. McCall, Ph.D., a graduate student in the Bruchas lab, to construct the remote controlled, optofluidic implant.

Senior author John A. Rogers, Ph.D., professor of materials science and engineering, University of Illinois at Urbana-Champaign, said:

“We used powerful nano-manufacturing strategies to fabricate an implant that lets us penetrate deep inside the brain with minimal damage. Ultra-miniaturized devices like this have tremendous potential for science and medicine."

With a thickness of 80 micrometers and a width of 500 micrometers, the optofluidic implant is thinner than the metal tubes, or cannulas, scientists normally use to inject drugs. When the scientists compared the implant with a typical cannula they found that the implant damaged and displaced much less brain tissue.

Researchers made the implant using semi-conductor computer chip manufacturing techniques. It has room for up to four drugs and has four microscale inorganic light-emitting diodes.

They installed an expandable material at the bottom of the drug reservoirs to control delivery. When the temperature on an electric heater beneath the reservoir rose then the bottom rapidly expanded and pushed the drug out into the brain.

Jeong et al.
Wireless Optofluidic Systems for Programmable In Vivo Pharmacology and Optogenetics.
Cell, 2015 DOI: 10.1016/j.cell.2015.06.058

Illustration: Courtesy of Jeong lab, University of Colorado Boulder.