In mice with noise-induced hearing loss, inflammation in a sound-processing region of the brain mediates ringing in the ears, revealed study in the open-access journal PLOS Biology by Shaowen Bao of the University of Arizona, and colleagues.
Recent studies indicate that hearing loss causes inflammation -- the immune system's response to injury and infection -- in the auditory pathway. But its contribution to hearing loss-related conditions such as tinnitus is still poorly understood. To address this gap in knowledge, Bao and his colleagues examined neuroinflammation -- inflammation that affects the nervous system -- in the auditory cortex of the brain following noise-induced hearing loss, and its role in tinnitus, in rodent models.
The results indicate that noise-induced hearing loss is associated with elevated levels of molecules called proinflammatory cytokines and the activation of non-neuronal cells called microglia -- two defining features of neuroinflammatory responses--in the primary auditory cortex.