In vivo optogenetic identification and manipulation of GABAergic interneuron subtypes

- Focal, low-intensity optogenetic stimulation improves interneuron characterization.
- Diode-probes allow flexible multisite perturbation of interneurons.
- Methods are needed to study interneuron subtypes within molecularly-defined classes.

Identification and manipulation of different GABAergic interneuron classes in the behaving animal are important to understand their role in circuit dynamics and behavior. The combination of optogenetics and large-scale neuronal recordings allows specific interneuron populations to be identified and perturbed for circuit analysis in intact animals. A crucial aspect of this approach is coupling electrophysiological recording with spatially and temporally precise light delivery. Focal multisite illumination of neuronal activators and silencers in predetermined temporal configurations or a closed loop manner opens the door to addressing many novel questions. Recent progress demonstrates the utility and power of this novel technique for interneuron research.