Capability of intensity discrimination in multiple receptor model of insect taste

A simple model in which one CNS taste neuron integrates inputs from multiple peripheral receptors is introduced in order to investigate the mechanism of acute intensity taste discrimination in flies. Information theory is applied to evaluate the acute ability of discrimination provided by the model. The present analysis is carried out under two statistical conditions concerning the uncertainty of receptor response. Based on experimental data obtained by Smith et al. (1983), we estimate the mutual information entropy of the model. The numerical results obtained here indicate that the uncertainty observed in a single receptor response is dramatically reduced by the central integration. Furthermore, each of the eleven stimulus intensity levels experimentally applied by Smith et al., can be discriminated completely by integrating the responses of the realistic number of receptors (33-212). Such a great improvement of the differential sensitivity in the model resolves the discrepancy between the low differential sensitivity of single sugar receptors (Smith et al., 1983) and the high sensitivity obtained in the feeding behavior (Dethier and Rhoades, 1954; Dethier and Bowdan, 1984) of the blowfly.