25

Figure: Coupled hair cells (left): Fluorescence microscopy image of a cell cluster of five coupled inner hair cells (pear-shaped with bright spots). The second cell from the left was loaded with a fluorescent dye that labels the synaptic ribbon using the patch-clamp technique. From there, the dye spreads into the neighbouring hair cells and marks the synaptic ribbons (bright spots). Source: Institute for Auditory Neuroscience / UMG. A “mini-syncytium” of three coupled inner hair cells (right); the connection is simplified as a tube formed by fused cell membranes: The electrical signals are transmitted via coupling of the cells. This mechanism reduces the stochastic noise of signal transmission at the ribbon synapses with the neurons forming the auditory nerve. From there the information is transmitted to a common target neuron in the brain, further reducing the noise and resulting in higher hearing sensitivity. Source: Jean et al., Nat Commun, 2020; Suppl. Part.