Fenton, G. E. | bioRxiv Science

bioRxiv2025

Neuronal recordings in head-fixed and freely-moving mole-rats

Mole-rats are subterranean rodents that have evolved remarkable sensory adaptations to life in underground tunnel systems, yet their neural mechanisms remain largely unexplored. Here, we present a protocol for in vivo electrophysiological recordings in awake, head-fixed, and freely moving African mole-rats (Fukomys anselli/micklemi), overcoming unique challenges of studying the neurobiology of subterranean species. For example, we find that mole-rat brain physiology impacts survival after surgeries, with higher carbon dioxide concentrations required for recovery compared to other rodents, likely due to a mutation in the chloride-potassium symporter KCC2. Having addressed the challenges, we used tetrodes and Neuropixels probes to record single-unit activity and local field potentials (LFP) across several cortical and subcortical regions for several weeks. We observed single units responsive to auditory and visual stimuli in the superior colliculus, and hippocampal recordings in freely moving mole-rats revealed prominent theta rhythms at frequencies lower than those observed in any other rodent species to date. Finally, we performed integrated three-dimensional and two-dimensional probe-track analysis within the same brain using tissue clearing, light sheet imaging, rehydration, and vibratome sectioning, and we present a newly developed stereotaxic brain atlas for implantation and histological alignment. The established methodology will guide future studies in comparative rodent neurobiology, providing further insights into neurobiological adaptations to subterranean environments. Given their phylogenetic and ecological similarities, we expect our protocols to be transferable to other subterranean species, including the widely studied naked mole-rat (Heterocephalus glaber). HighlightsO_LIProtocols for chronic and acute electrode implantations in mole-rats C_LIO_LIStereotaxic brain atlas for the Ansells mole-rat (https://doi.org/10.17617/3.UNDKRO) C_LIO_LINeuropixels and tetrode single-unit recordings in head-fixed and freely moving mole-rats C_LIO_LIIntegrated 3D (tissue clearing) and 2D (histology) probe-track analysis within the same brain C_LIO_LIDiscovery of low-frequency hippocampal theta rhythm in Ansells mole-rats C_LI

neuroscience↗

bioRxiv2019

Physiological Basis of noise-induced hearing loss in a tympanal ear

Acoustic overexposure, such as listening to music too loud and too often, results in noise-induced hearing loss. The pathologies of this prevalent sensory disorder begin in the synapses of the primary auditory receptors, their postsynaptic partners and supporting cells. The extent of noise-induced damage, however, is determined by over-stimulation of primary auditory receptors. When over-stimulated, an excessive amount of positive ions flood into the primary auditory receptors, triggering the activation of ion channels and possibly disrupting their ability to encode sound. A systematic characterisation of the electrophysiological function of primary auditory receptors is warranted to understand how noise-exposure impacts on downstream targets, where the pathologies of hearing loss begin. Here, we used the experimentally-accessible locust ear to characterise noise-induced changes in the auditory receptors. Although, we found a decrease in ability of the primary auditory neurons to encode sound, this is probably due to pathologies of their supporting cells.

neuroscience↗