A simple optogenetic system for behavioral analysis of freely moving small animals.

We present a new and simple optogenetic system for the behavioral analysis of small animals. This system includes a strong LED ring array, a high-resolution CCD camera, and the improved channelrhodopsin ChRGR. We used the system for behavioral analysis with the nematode Caenorhabditis elegans as a model, and we found that it can stimulate ChRGR expressed in the body wall muscles of the animals to modulate the behavior. Our results indicate that this system may be suitable for optogenetic behavioral analysis of freely moving small animals under various conditions to understand the principles underlying brain functions.