Optrode Arrays for Multi-Circuit Dissection

Optogenetics has been successfully applied to understand the mechanisms of neuropsychiatric diseases through the precise temporal control of specific neural circuitries. However, it remains a great challenge to integrate optogenetic modulation with electrophysiological recordings in multiple brain regions in vivo. In this study, a simplified method for the fabrication and electrochemical modification of the multicircuit optrode arrays was developed. The modified optrode arrays exhibited a significantly higher capacitance and lower electrochemical impedance at 1 kHz as compared to unmodified optrodes. The optrode arrays were chronically implanted into the brain of VGAT-ChR2 transgenic mice. Spontaneous action potentials and local field potentials as well as light-evoked responses were obtained in 4 different brain regions in vivo. The crossarea synchronizations were analyzed and the localizations of the implanted optrode arrays were confirmed by 4', 6-diamidino-2-phenylindole immunofluorescence staining. All these characteristics are greatly desired in optogenetic applications, and the fabrication method of the optrodes can be easily integrated with other in vivo techniques to build more advanced tools for the dissection of neural circuitry.