Exploring the link between adult-onset hearing loss and visual adaptations in mice

To adapt to changing environments and bodily functions across the lifespan, many mammals rely on compensatory changes in the brain. One major change as mammals age is that individual senses, such as hearing or vision, can be weakened or lost. Preclinical work suggests that when one sense is lost, cortical brain pathways adapt to improve the processing of remaining senses. Hey-Kyoung Lee and colleagues, from Johns Hopkins University, extended this work in their JNeurosci paper by exploring the relationship between adult-onset hearing loss and visual adaptations in mice. 

The researchers measured neural responses in a key visual brain area as mice were presented with visuals in either their immediate (focal) or peripheral visual fields. Hearing loss in adulthood didn't affect neural responses to visuals in focal visual fields, but neural responses to visuals in the periphery were strongly dampened. Behavioral measures of mice with adult-onset hearing loss revealed these mice perceived only peripheral visuals with higher clarity than mice without hearing loss, suggesting that this activity change may represent more efficient neural representations of peripheral visuals. 

Says Lee, "Our work suggests, rather counterintuitively, that dampening neural activity may be beneficial by improving the brain's efficiency at processing information. Another main conclusion is that, at least in adults, [this visual brain area's] adaptation to hearing loss does not improve all visual function." The researchers plan to follow up on this work by exploring specific mechanisms in this visual brain area that can be leveraged to improve adult visual function.