Wirelessly Operated, Implantable Optoelectronic Probes for Optogenetics in Freely Moving Animals

Recording and interrogating brain activities using optical methods have become emerging technologies in neuroscience. Traditional tools for optogenetic stimulation in the deep brain are mostly based on implantable fibers, imposing constraints on the animal movement. Recently developed microscale light-emitting diodes (micro-LEDs), which can be wirelessly operated, serve as injectable light sources that directly interact with neural systems. Here, we exploit a wirelessly controlled, implantable system for optogenetic studies in behaving animals. Thin-film indium gallium nitride (InGaN)based blue micro-LEDs transferred onto flexible probes are injected into the animal brain and optically activate channelrhodopsin-2 expressing neurons. A customized circuit module with a battery is employed to modulate the micro-LED, which is remotely controlled at a distance up to 50 m via 2.4-GHz radio frequency communications. The systems are implemented on freely moving mice, and demonstrate optogenetic modulation of locomotive behaviors in vivo. Moreover, independent and synchronous control of multiple animals is accomplished with the communication unit in the design circuit. The proposed system provides the potential for advanced optical neural interfaces and offers solutions to study complicated animal behaviors in neuroscience research.