Wireless electrocochleography in awake chinchillas: a model to study multimodal modulations at the peripheral level

The discovery and development of electrocochleography (ECochG) in animal models has been fundamental for its implementation in clinical audiology and neurotology. In our laboratory, the use of round-window ECochG recordings in chinchillas has allowed a better understanding of auditory efferent functioning. In previous works, we gave evidence of the corticofugal modulation of auditory-nerve and cochlear responses during visual attention and working memory. However, whether these cognitive top-down mechanisms to the most peripheral structures of the auditory pathway are also active during audiovisual crossmodal stimulation is unknown. Here, we introduce a new technique, wireless ECochG to record compound-action potentials of the auditory nerve (CAP), cochlear microphonics (CM), and round-window noise (RWN) in awake chinchillas during a paradigm of crossmodal (visual and auditory) stimulation. A total of four chinchillas were successfully recorded during the experimental protocol. There were non-significant differences in CAP, CM, and RWN amplitudes in response to auditory stimulation alone (clicks and tones) as compared to audio-visual crossmodal stimulation. These results suggest that cognition, such as attention or working memory, is needed for the corticofugal modulation of auditory-nerve and cochlear responses. In addition, we introduce the use of wireless ECochG in animal models as a useful tool for translational research.