Auditory activity in the absence of sound

A study published in Nature(1) shows that electrical activity can be detected in the auditory nerve before the onset of hearing. Tritsch and colleagues, at the Johns Hopkins School of Medicine in Baltimore, showed that a group of cells called the Kolliker's organ located next to sensory hair cells release ATP in the immature cochlea. This ATP in turn causes hair cells to release glutamate triggering auditory nerve fibres. The researchers speculate that this may play an important role in setting up the auditory map within the brain.

The Kolliker's organ disappears and the spontaneous release of ATP stops after the onset of hearing. However, the researchers point out that cochlear injury can trigger the release of ATP in the mature cochlea and, significantly, hair cells continue to express ATP receptors. This research may therefore provide insight into conditions such as tinnitus.

(1) Tritsch et al. (2007). The origin of spontaneous activity in the developing auditory system. Nature 450, 50-55. (external link, opens new browser window)