Dopamine in the Auditory System of Vocal Toadfishes: Potential Adaptation for Noisy Aquatic Environments

Anthropogenic noise negatively impacts the lives of aquatic animals including their ability to reproduce and survive. However, some animals are still able to thrive within these increasingly noisy environments and therefore must have some adaptations that allow them to attend to salient signals within noise. All major classes of vertebrates have cholinergic neurons in the hindbrain that function as auditory efferents, meaning that they project to the inner ear. Even less is known about dopamine neurons that project to the inner ear, but studies in rodents have proposed that one role of both types of efferents is to protect the ear from damage due to noise. Therefore, research in aquatic systems should focus on animals that use acoustic communication in reproductive contexts, like the oyster toadfish (Opsanus tau), which are regularly exposed to high levels of anthropogenic sounds. Examining the role of modulatory neurotransmitters, like dopamine, within the auditory system, will provide important insights to understanding neural adaptations for survival in environments exposed to increasing levels of anthropogenic noise.