Colocalized, Bidirectional Optogenetic Modulations in Freely Behaving Animals with a Wireless Dual-Color Optoelectronic Probe

The precise control of neural activities at both cellular and circuit levels reveals significant impacts on the fundamental neuroscience explorations and medical applications. Optogenetic methods provide efficient cell-specific modulations, but state-of-the-art technologies lack the ability of simultaneous neural activation and inhibition in a same brain region of freely moving animals. Here we report bidirectional neuronal activity manipulation accomplished by a wireless, dual-color optogenetic probe in synergy with the co-expression of two spectrally distinct opsins (ChrimsonR and stGtACR2) in a rodent model. Based on vertically assembled, thin-film microscale light-emitting diodes (micro-LEDs) on flexible substrates, the dual-color probe shows colocalized red and blue emissions and allows chronic in vivo operations with desirable biocompatibilities. In addition, we discover that neurons co-expressing the two opsins can be deterministically evoked or silenced under red or blue irradiations. Implanted in behaving mice, the wirelessly controlled dual-color probe interferes with dopaminergic neurons in the ventral tegmental area (VTA), increasing or decreasing dopamine levels with colocalized red and blue stimulations. Such bidirectional regulations further generate rewarding and aversive behaviors of freely moving animals in a place preference test. The technologies established here will create numerous opportunities and profound implications for the brain research. ### Competing Interest Statement The authors have declared no competing interest.