Thermal-noise-limited transduction observed in mechanosensory receptors of the inner ear

Simultaneous recordings of the spontaneous mechanical input fluctuations and the electrical output fluctuations in hair cells that serve as biological microphones show that the Brownian motion of the mechanoceptive organelle, the hair bundle, is often strongly correlated with the fluctuations of the transmembrane voltage. This correlation stems from transduction of the spontaneous input noise and shows that these cells can almost reach the sensitivity limit imposed by the thermal noise at their input.