Reversible external auditory canal ligation (REACL): A novel surgical technique to induce transient and reversible hearing loss in developing rats

Abstract

Background: Cases of sensory loss provide an excellent model to study the plastic nature of cortical sensory systems. Models of reversible sensory loss are particularly useful for establishing the timeline of various critical periods for cortical plasticity. However, there currently is an absence of adequate methods to produce reversible hearing loss in neonatal and developing rodents. New method: We propose a novel and reversible adaptation of an existing surgical technique—external auditory canal ligation (EACL)—that produces a reliable and moderate hearing loss. Results: Auditory brainstem responses (ABRs) were used to measure both the magnitude of the hearing loss induced by EACL and the auditory thresholds following hearing restoration. The EACL and reopening procedures, as assessed by visual inspection, had success rates of 81% and 78%, respectively. The average hearing thresholds, as assessed with ABRs, increased by nearly 40 decibels across all tested frequencies. Hearing thresholds returned to normal levels following the reopening procedure. Comparison with existing methods: Our procedure yields similar benefits to other methods, such as producing a reliable and moderate hearing loss that is entirely reversible. Furthermore, to our knowledge, it is the first that can be performed in neonatal rodents, thus allowing researchers the opportunity to assess the effects of sensory loss on behavior and cortical neurophysiology during developmental critical periods. Conclusion: Our modified technique of reversible external auditory canal ligation offers an easy, and reliable method to induce a transient state of hearing loss that mimics naturally occurring congenital conductive hearing loss.