Hearing is enhanced by vagus nerve stimulation paired with repetitive sounds



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Potential therapeutic benefits for a range of conditions including tinnitus have been glimpsed thanks to newly published research involving vagus nerve stimulation (VNS) in rats.

Previous research has already indicated that extensive auditory training can alter the neural response to the trained sound throughout the auditory pathway, while this VNS-sound pairing paradigm has been successfully used both pre-clinically in patients with tinnitus.

The vagus runs from the cranium to the gut and is a key nerve in the autonomic nervous system. In rats, this nerve was stimulated while they were exposed daily, for 20 days, to sounds at specific frequencies. From the responses to these tones in the exposed rats and a control group, the researchers in this latest study concluded that VNS-tone pairing significantly increased the response to the paired tone frequency. In other words, auditory processing (hearing) of those tones was improved.

This is the first study to document both cortical and subcortical plasticity following VNS-sound pairing, thus further confirming positive clinical implications for such a paradigm.

"This method can change even the earliest levels of the auditory system, which [has] been viewed as the most difficult to change," said study co-author, Michael Kilgard.

"Future studies," reads the paper "are needed to dissect the functional consequences of the effects of VNS in each auditory region. This defines testable hypotheses for future human and animal studies to characterize plasticity throughout the auditory pathway and functional consequences in the context of disease."

Funding for the study included a National Institute of Deafness and Other Communications Disorders Grant to the research leader, Crystal Engineer. The full article can be read here in the Journal of Neurophysiology.

Source: Medical Xpress