The Course of Habituation of the Proboscis Extension Reflex Can Be Predicted by Sucrose Responsiveness in Drosophila

Münire Özlem Çevik,Ahmet Erden,Hiromu Tanimoto

doi:10.1371/journal.pone.0039863

Münire Özlem Çevik, Ahmet Erden + Show 1 more

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https://doi.org/10.1371/journal.pone.0039863

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Journal: PloS one	Publication Date: Jun 26, 2012
Citations: 36	License type: CC BY 4.0

Affiliation: Bolu Abant İzzet Baysal University

Abstract

The proboscis extension reflex (PER) is triggered when insects’ gustatory receptors contact appetitive stimuli, so it provides a behavioral readout for perceptual encoding of tastants. Research on the experience dependent modulation of PER in Drosophila has been hindered by the difficulty of obtaining reliable measures of memory-driven change in PER probability in the background of larger changes induced by physiological state. In this study, we showed that the course of PER habituation can be predicted by the degree of sucrose responsiveness in Drosophila. We assessed early response parameters, including the number of proboscis extensions and labellar movements in the first five trials, the trial to start responding, and the trial to make the first stop to quantify responsiveness, which predicted the upcoming pattern of both the short-term and 1 hour memory of PER habituation for individual flies. The cAMP signaling pathway mutant rutabaga displayed deficits in attunement of perceptual salience of sucrose to physiological demands and stimulus-driven sensitization.

Highlights

Habituation refers to the reduction in the probability or intensity of a response that occurs upon the repetition of the eliciting stimulus
In an attempt to understand how response profiles of individual flies changed across 1–4 hfd, we plotted the proportion of flies that were nonresponsive, or responded to make either 1–10 or 11–20 totalPERs (Figure 2d)
60% of all flies that emitted 4–5 labellar movements in the first five trials were still responding on the last trial of the session (Figure 6c, green curve). These results suggest that labellar movements have a higher threshold of modulation by hunger than proboscis extension reflex (PER), and their sensitization is a reliable predictor of high sucrose responsiveness

Summary

Introduction

Habituation refers to the reduction in the probability or intensity of a response that occurs upon the repetition of the eliciting stimulus. Often considered as the simplest form of learning, it underlies the selection process that allocates attention to relevant stimuli, while diminishing responsiveness to the redundant background [1,2]. Insects respond to appetitive stimuli with an extension of their mouthparts called the proboscis, habituation of which has been reported several years ago for the housefly [3]. More recent studies showed that in honeybees, repeated stimulation of the antennae by sucrose causes a short-term habituation of the proboscis extension reflex (PER), but may increase its threshold for hours [4]

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