In vivo electrophysiology in head-fixed and freely moving mole-rats.

Mole-rats are subterranean rodents with sensory and physiological adaptations to life in underground tunnels, yet their neurobiology remains largely unexplored. We present methods for in vivo electrophysiological recordings in awake, head-fixed, and freely moving African mole-rats (Fukomys anselli and Fukomys micklemi), addressing their unique anatomy and physiology. We report anesthesia, analgesia, and surgical procedures and find that elevated carbon dioxide concentrations are beneficial for recovery, likely due to a mutation in the potassium-chloride symporter KCC2. We also present a stereotaxic mole-rat brain atlas to guide electrode placement. Using tetrodes and silicon probes, we recorded single-unit activity and local field potentials in the cortex, hippocampus, and superior colliculus. Lastly, we present combined tissue clearing, light-sheet imaging, rehydration, and vibratome sectioning to enable 3D and 2D probe-track analyses within the same brain. The methodology will facilitate comparative studies among subterranean rodents, including the naked mole-rat (Heterocephalus glaber), to elucidate neurobiological adaptations to dark subterranean environments.