A physicochemical model of odor sampling

We present a general physicochemical sampling model for olfaction, based
on established pharmacological laws, in which arbitrary combinations of
odorant ligands and receptors can be generated and their individual and
collective effects on odor representations and olfactory performance
measured. Individual odor ligands exhibit receptor-specific affinities and
efficacies; that is, they may bind strongly or weakly to a given receptor,
and can act as strong agonists, weak agonists, partial agonists, or
antagonists. Ligands interacting with common receptors compete with one
another for dwell time; these competitive interactions appropriately
simulate the degeneracy that fundamentally defines the capacities and
limitations of odorant sampling. The outcome of these competing
ligand-receptor interactions yields a pattern of receptor activation
levels, thereafter mapped to glomerular presynaptic activation levels
based on the convergence of sensory neuron axons. The metric of greatest
interest is the mean discrimination sensitivity, a measure of how
effectively the olfactory system at this level is able to recognize a
small change in the physicochemical quality of a stimulus.