Chemical Senses Advance Access originally published online on May 7, 2007
Chemical Senses 2007 32(6):535-541; doi:10.1093/chemse/bjm022
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Dose-Dependent Nonassociative Olfactory Learning in a Fly
Department of Experimental Biology, Section of General Physiology, University of Cagliari, Monserrato-Cagliari 09042, Italy
Correspondence to be sent to: Anna Maria Angioy, Department of Experimental Biology, Section of General Physiology, University of Cagliari, Monserrato-Cagliari 09042, Italy. e-mail: amheart{at}unica.it
| Abstract |
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Olfactory sensory stimulation induces a fast-phase arrest response (FPA-R) of the blowfly heart activity that has been described as a sensitive tool for testing insect reactivity to odor perception. We analyzed FPA-R occurrence to repeated olfactory stimulation with low and high 1-hexanol concentrations that are behaviorally attractant and repellent, respectively, in the blowfly. FPA-R occurrence diminished and ceased with repeated presentations of low and medium odor concentrations, according to dynamics inversely related to odor doses. On the other hand, repeated stimulation with higher odor concentrations induced persistent FPA-Rs. Sensory input amplitude to repeated presentations of singly tested odor concentrations did not change throughout stimulation sessions. A spontaneous restoration of FPA-R to olfactory stimulation was recorded 30 min after cessation of FPA-R to a previous olfactory stimulation session. However, a prompt restoration of FPA-R to olfactory stimulation after cessation of FPA-R was obtained following mechano-taste stimulation of labellar sensilla. Our findings show that the FPA-R habituates to olfactory sensory stimulation with low and medium odor concentrations according to dynamics inversely related to odor intensities. On the other hand, the FPA-R does not habituate to higher odor concentrations. Therefore, flies learn to disregard nonaversive odor information, but they cannot ignore iterative detection of a repellent volatile.
Key words: habituation, heart response, insect, odor information
Accepted 14 March 2007