Automated device for simultaneous photometry and electrophysiology in freely moving animals

Photometry and electrophysiology are powerful tools for investigating brain-behavior relationships. Combining these techniques would allow us to ask previously un-addressable questions, such as how neuromodulators impact neuronal firing rates. Current options are highly limited—requiring a substantial loss in data-quality or severely restricting naturalistic-movement. These drawbacks arise from engineering-limits on devices that allow optically-tethered subjects to move freely. Here, we introduce a device that overcomes these challenges. Its automated orientation-tracking system allows subjects to move freely for multiple-hours with minimal supervision and without sacrificing data-quality. The device is modular and adaptable, being compatible with most recording systems and equipped for added functionality (e.g., optogenetics). To demonstrate its utility, we simultaneously tracked extracellular striatal dopamine and single-neuron firing as mice performed a reward-learning task. Mice showed excellent mobility, and we observed robust trial-by-trial correlations between striatal firing and dopamine signaling. This device provides a powerful tool that outperforms current commercial solutions.