CODING OF ODOR INTENSITY IN A SENSORY NEURON

A deterministic biophysical model of an olfactory sensory neuron under constant stimulation is presented with the aim of describing the succ essive conversion steps, including receptor activation, conductance ch ange, receptor potential and firing frequency, that are involved in th e coding of odorant concentration. This model is divided in two parts. The odorant-sensitive part (OSP), consisting of one cylindrical dendr ite, is connected to the odorant-insensitive part (OIP), corresponding to passive dendrite, soma and axon. Each part exerts a specific effec t on the coding properties of the conversion steps, i.e. their magnitu de, sensitivity and dynamic range. The maximum conductance of the OSP affects positively all coding properties whereas the input resistance of the OIP, which depends on its size and shape, affects positively th e sensitivity and negatively the dynamic range. These findings are hel pful for understanding the input-output properties of many types of ne urons.