Opto-Avoidance-Elevated Plus Maze protocol to study positive or negative valence upon optogenetic stimulation in the mouse brain

The elevated plus maze (EPM) apparatus consists of two open arms that provide aversive spaces and two closed arms that provide protective and welcoming spaces. Here, we present a protocol to implement the classical EPM apparatus in a real-time optogenetic environment to address behavioral avoidance in mice. We describe steps for performing stereotaxic surgery, mouse manipulation, and experimental setup. Finally, we detail the procedures required for the Opto-Avoidance-EPM test in which the naturally preferred closed arms are selectively paired with optogenetic stimulation. For complete details on the use and execution of this protocol, please refer to Serra et al.¹.