Measurements of odours based on response analysis of insect olfactory receptor neurons

Different possibilities to record odour concentrations based on responses of insect olfactory receptor neurons (ORNs) for odour sensing were studied. The ORNs were located in blowfIies (Calliphora vicina), mosquitoes (Aedes communis), pine weevils (Hylobius abietis), and also in trogossitid beetle (Trogossita japonica). The odour stimulation method is based on odour exposure sequences to activate action potential rates quantitatively as a function of odour concentration in air exposure. First, an analysis system was developed for the extracellular action potentials (or nerve pulses). A power law was applied and its dependence (similar to Stevens’ law in psychophysics) was also tested on gas chromatography method and obtained for the action potential rate of ORN responses versus odour vapour concentration in measurements with metal microelectrodes from blowfly ORNs. The results show that the insects ORNs are sensitive and specific odour sensor.