Better-than-normal hearing unlocked by gene tweak

Age-related hearing loss was primarily thought to be caused by damage to or destruction of hair cells. A row of inner hair cells in the snail-like cochlea converts sound vibrations into electrical signals that are transmitted to the brain via the auditory nerve. However, recent research suggests that damage to the synapses that connect these hair cells to auditory nerve fibers may be the first step in the process of hearing loss.

A new study by researchers at Michigan Medicine’s Kresge Hearing Research Institute found that tweaking the expression of a particular protein to increase the number of synapses improved auditory processing to better-than-normal levels in otherwise healthy mice.

Auditory processing is different to hearing. Whereas hearing is the conversion of sound waves to auditory signals that are sent to the brain, auditory processing is what the brain does with the auditory information it receives from the ears.

The researchers had previously experimented with neurotrophin-3 (Ntf3), a protein that controls the survival and differentiation of neurons in mammals. A 2014 study found that an overproduction of Ntf3 led to more synapses and boosted their regeneration following exposure to two hours of 100-dB noise. Then, in 2022, a study found that higher levels of Ntf3 improved age-related hearing loss in middle-aged mice.

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