Fluorescing Neurons (IMAGE) California Institute of Technology Caption Optogenetic (green) and chemogenetic (red) transgenes are expressed in the dopaminergic (blue) neurons in the dorsal raphe nucleus. Dopaminergic neurons are implicated in moderating the sleep/wake cycle. Credit Gradinaru lab/Caltech Usage Restrictions WITH IMAGE CREDIT License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.