Chemosensory input and taste discrimination in the blowfly.

Simultaneous recording of behavioral responses and action potentials from single chemoreceptors in the proboscis of intact blowflies revealed that acceptance of a solution can be mediated either by input from one water receptor or from one salt receptor. Rejection of higher concentrations of salt is mediated by the same salt receptor. A difference of three impulses in the first 100 milliseconds of activity can determine whether the fly accepts or rejects the solution.