OLFACTORY TRANSDUCTION IS INTRINSICALLY NOISY

The sources of noise that limit olfactory signal detection were invest igated in dissociated rat olfactory receptor cells. Near-threshold odo rant-evoked currents exhibited large random fluctuations. However, sim ilar fluctuations were observed in the absence of applied odorants whe n currents were induced by elevating the intracellular cyclic AMP conc entration. This suggests that the fluctuations reflect noise intrinsic to the transduction mechanism, rather than the quantal nature of an o dorant stimulus. For many odorants, this intrinsic noise may preclude the reliable detection of single odorant molecules.