Harnessing thermal fluctuations for selectivity gain

Abstract

Selectivity of olfactory receptor neuron (ORN) is compared with that of its receptor proteins (R) with fluctuations of odor binding-releasing process taken into account. The binding-releasing process is modeled as N Bernoulli trials, where N is the total number of R per ORN. Dimensionless selectivities for both R and ORN are introduced and compared with each other. It is found the ORN's selectivity can be much higher then that of its receptor proteins. This effect is concentrationdependent. Possible application for biosensors is discussed.

Максимізація Селективності Ольфакторного Рецепторного Нейрона В Підпороговому Режимі

“…The reception regime in which fluctuations in the number of bound RPs substantially affect the spike generation, the sub-threshold regime, is also considered (Section 2.1.1). Previous results obtained in the framework of this model [8] showed that it is possible to obtain the selectivity of ORN in the sub-threshold regime that considerably exceeds the selectivity of its RPs.…”

“…The selectivity of RP and ORN can be defined in various ways. Here, we follow the definitions from work [8]. They exclude the consideration of the concentration and the dissociation reaction constant 𝐾 [see Eq.…”

“…First, it is simpler to deal with 𝑝. Besides, formula (8) given below provides an unambiguous relationship between 𝐾 and 𝑝, if the concentration 𝑐 is fixed, or between 𝑐 and 𝑝 if the dissociation constant 𝐾 is fixed. Second, the olfactory neuron has no access to the 𝐾-and 𝑐-values, whereas the information about the total RP number 𝑁 and the number 𝑛 of bound RPs on the neuron surface [which, according to formula (2), is equivalent to knowing the 𝑝-value] is exactly what is subjected to a further processing in the ORN and invokes the generation of output impulses.…”

“…Earlier, it was predicted theoretically [8] that if odorants are applied to the ORN at concentrations lower than it is required for a stable generation of spikes (sub-threshold ones) so that only their random generation due to fluctuations is possible, the ORN selectivity can be substantially enhanced. In this paper, possible ORN parameters and concentrations that provide the maximum enhancement of selectivity are estimated.…”