A wireless, implantable and fully internal device for optogenetic (light-mediated) manipulations of mouse neural circuits is reported in a study published online this week in Nature Methods. The tool is made of readily available materials and was used to modulate walking behavior, pain perception and gene expression through the light-induced activation of different neural circuits.
Optogenetics allows the precise stimulation of specific cell types (usually neurons) that have been genetically sensitized to light. When studying the function of neural circuits in freely behaving animals using optogenetics, it is important that the light delivery device does not restrict these behaviors. Similarly, optogenetic access to neurons in the extremities requires small, light-weight light sources.
Ada Poon and colleagues developed implantable light sources that weigh 20-50 mg and are therefore significantly smaller and lighter than previously described devices. They can be implanted into the mouse brain or close to target neurons in the animal’s leg or spinal cord. These devices are powered wirelessly and use a blue LED to generate sufficient light intensity to stimulate cells that have been genetically engineered to respond to light and induce neural activity in desired neural populations.
Due to their small size, these devices should open up new avenues in behavioral neuroscience as they allow for long-term manipulations of neural activity. In addition, neural circuits that have previously not been accessible to optogenetic approaches because the light-delivery devices were too bulky may now become amenable.