  A mechanism is proposed for increasing selectivity of olfactory bulb
projection neurons as compared to the olfactory receptor neurons, which could
operate under low odor concentration, when the lateral inhibition mechanism
becomes inefficient. The mechanism proposed is based on the threshold-type
reaction to stimuli a projection neuron receives from the receptor neurons, the
stochastic nature of those stimuli and electrical leakage in the projection
neurons. The mechanism operates at the level of individual projection neuron
and does not require involvement of other bulbar neurons.
  Keywords: olfactory receptor neuron; projection neuron; selectivity;
stochastic process; theory
