Receptor heterogeneity and its effect on sensitivity and coding range in olfactory sensory neurons

Signal processing in the olfactory system is initiated by binding of odoran t molecules to receptor molecules embedded in the membranes of sensory neur ons. Most analyses of odorant-receptor interaction focus on one or more typ es of odorants binding with one type of receptors. Here, two basic models o f this first step are investigated under the assumption that the population of receptors is not homogenous and is characterized by different activatio n/deactivation rates. Both, discrete and continuous variation of the rates are considered. The steady-state characteristics of the models are derived. In addition, time to crossing a threshold, defined as a response time, is also investigated. The achieved results are compared with those valid for m odels with the homogenous population of receptors and interpreted in terms of information coding. The obvious implications of the modeling study-that the heterogeneity of receptors enlarges the coding range and increases the sensitivity of the system-are quantified. (C) 2001 Society for Mathematical Biology.