This is a Discovery Research Grant awarded to Dr Laura Hurley at Indiana University, USA, in 2022.
Serotonin is a chemical messenger that is released in the brain and is involved in many processes in the body. It is well-known for its effect on mood and its link to depression. However, serotonin is also involved in regulating social behaviour and cognition, and in how the brain processes and perceives sound. Social isolation and hearing loss have separately been shown to reduce the response of the hearing brain to serotonin. This can lead to changes in the way that the auditory brain processes social calls.
Hearing loss can worsen the social isolation already experienced by many older people and lead to depression, anxiety and cognitive decline. It is therefore important to understand how these two factors interact with each other and their combined effect on how serotonin regulates the hearing brain and sound perception.
In this project, Dr Laura Hurley will investigate the effects of noise-induced hearing loss, social isolation, and their combination on how serotonin regulates the hearing brain. To do this, she will use a mouse model of hearing loss similar to progressive hearing loss in people. In these mice, exposure to damaging levels of noise in early adulthood results in increased hearing loss as the mice age.
She will study how social isolation, hearing loss, and the combination of the two influence the activity of neurons that produce serotonin during a social interaction, and how hearing loss and isolation alter the connections between these neurons and the auditory brain.
Dr. Amanda Lauer at Johns Hopkins University will collaborate in this work to measure the combined effects of social isolation and hearing loss on anxiety-like behaviours in mice. The aim is to understand if there are enhanced effects on the social regulation of sound processing and behaviour when the mice are both isolated and have hearing loss.
The results from this study will lead to the development of a model of how serotonin is involved in the communication and emotional problems that are linked to hearing loss and social isolation. This model would be useful in developing treatments for these conditions that target serotonin activity in the hearing brain.