Olfactory coding in <i>Drosophila</i> larvae investigated by cross-adaptation

Boyle, Jennefer; Cobb, Matthew

doi:10.1242/jeb.01810

Cited by 32 publications

(49 citation statements)

References 33 publications

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“…This is because the nonassociative influences of animal handling, of odor exposure, and of sugar exposure in the trained but not the naïve larvae can confound such a comparison (Rescorla 1967;Quinn et al 1974;Lieberman 2004) (in particular odor exposure effects are well documented for larval Drosophila: Cobb and Domain 2000; Boyle and Cobb 2005;Colomb et al 2007;Larkin et al 2010). Given that paired, unpaired and baseline groups are all equated for these aspects of exposure, such exposure effects are not immediately plausible explanations for behavioral differences between these experimental conditions.…”

Section: "Baseline" Behavior After Trainingmentioning

confidence: 99%

The impact of odor–reward memory on chemotaxis in larval Drosophila

et al. 2015

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How do animals adaptively integrate innate with learned behavioral tendencies? We tackle this question using chemotaxis as a paradigm. Chemotaxis in the Drosophila larva largely results from a sequence of runs and oriented turns. Thus, the larvae minimally need to determine (i) how fast to run, (ii) when to initiate a turn, and (iii) where to direct a turn. We first report how odor-source intensities modulate these decisions to bring about higher levels of chemotactic performance for higher odor-source intensities during innate chemotaxis. We then examine whether the same modulations are responsible for alterations of chemotactic performance by learned odor "valence" (understood throughout as level of attractiveness). We find that run speed (i) is neither modulated by the innate nor by the learned valence of an odor. Turn rate (ii), however, is modulated by both: the higher the innate or learned valence of the odor, the less often larvae turn whenever heading toward the odor source, and the more often they turn when heading away. Likewise, turning direction (iii) is modulated concordantly by innate and learned valence: turning is biased more strongly toward the odor source when either innate or learned valence is high. Using numerical simulations, we show that a modulation of both turn rate and of turning direction is sufficient to account for the empirically found differences in preference scores across experimental conditions. Our results suggest that innate and learned valence organize adaptive olfactory search behavior by their summed effects on turn rate and turning direction, but not on run speed. This work should aid studies into the neural mechanisms by which memory impacts specific aspects of behavior.

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Section: "Baseline" Behavior After Trainingmentioning

confidence: 99%

The impact of odor–reward memory on chemotaxis in larval Drosophila

et al. 2015

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“…That is, any associative training procedure obviously requires exposure to the to-be-associated stimuli, i.e., to both the odorant and the reward. Odor exposure is often found to reduce odor preferences in larval Drosophila (Boyle and Cobb, 2005) [see discussion in Colomb et al (2007) and Gerber and Stocker (2007)]. If in the Sap47 156 mutants such a decrease in preference would be particularly strong, this could feign an "associative" defect.…”

Section: Sap47mentioning

confidence: 99%

Behavioral and Synaptic Plasticity Are Impaired upon Lack of the Synaptic Protein SAP47

Saumweber¹,

Weyhersmüller²,

Hallermann³

et al. 2011

J. Neurosci.

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The synapse-associated protein of 47 kDa (SAP47) is a member of a phylogenetically conserved gene family of hitherto unknown function. In Drosophila, SAP47 is encoded by a single gene (Sap47) and is expressed throughout all synaptic regions of the wild-type larval brain; specifically, electron microscopy reveals anti-SAP47 immunogold labeling within 30 nm of presynaptic vesicles. To analyze SAP47 function, we used the viable and fertile deletion mutant Sap47 156 , which suffers from a 1.7 kb deletion in the regulatory region and the first exon. SAP47 cannot be detected by either immunoblotting or immunohistochemistry in Sap47 156 mutants. These mutants exhibit normal sensory detection of odorants and tastants as well as normal motor performance and basic neurotransmission at the neuromuscular junction. However, short-term plasticity at this synapse is distorted. Interestingly, Sap47 156 mutant larvae also show a 50% reduction in odorant-tastant associative learning ability; a similar associative impairment is observed in a second deletion allele (Sap47 201 ) and upon reduction of SAP47 levels using RNA interference. In turn, transgenically restoring SAP47 in Sap47 156 mutant larvae rescues the defect in associative function. This report thus is the first to suggest a function for SAP47. It specifically argues that SAP47 is required for proper behavioral and synaptic plasticity in flies-and prompts the question whether its homologs are required for proper behavioral and synaptic plasticity in other species as well.

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“…There are constraints in how similarity judgments can be obtained from humans and flies, because only the former are able to follow verbal instructions. We therefore used the most reliable methods for each species, semantic-free scaling of odor quality in humans (10) and cross-adaptation experiments, in which the change of the behavior in response to an odor after adaptation to another odor is measured, in flies (29). Perceived similarity between a set of nine odors in flies was measured (see Methods, Fig.…”

Section: Judgment Of Odor Intensity In Humans and Fruit Fliesmentioning

confidence: 99%

Influence of odorant receptor repertoire on odor perception in humans and fruit flies

Keller

Vosshall

2007

Proc. Natl. Acad. Sci. U.S.A.

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The olfactory system is thought to recognize odors with multiple odorant receptors (ORs) that are activated by overlapping sets of odorous molecules, ultimately generating an odor percept in the brain. We investigated how the odor percept differs between humans and Drosophila melanogaster fruit flies, species with very different OR repertoires. We devised high-throughput single fly behavior paradigms to ask how a given OR contributes to the odor percept in Drosophila. Wild-type flies showed dose-and stimulus-dependent responses to 70 of 73 odors tested, whereas mutant flies missing one OR showed subtle behavioral deficits that could not be predicted from the physiological responses of the OR. We measured human and fly judgments of odor intensity and quality and found that intensity perception is conserved between species, whereas quality judgments are species-specific. This study bridges the gap between the activation of olfactory sensory neurons and the odor percept.behavior ͉ Drosophila ͉ genetics ͉ olfaction ͉ psychophysics D espite the wealth of knowledge about the molecular basis of olfaction, little is known about how the odor percept forms in the brain. The identification of hundreds of odorant receptor (OR) genes (1), each encoding a different seven-transmembrane domain protein, provided an initial mechanistic explanation for how animals can discriminate a large number of chemical stimuli. Animals are thought to be able to identify and distinguish smells because each OR is activated by a specific set of odors and each odor activates a combination of ORs, a process known as combinatorial coding (2-6). A typical OR is sensitive to a few compounds at low concentrations and to a wider range of compounds at higher concentrations (5, 6). OR repertoires differ considerably in size between species, from Ϸ1,200 in rodents to Ϸ400 in humans, and 61 in the fly (Drosophila melanogaster) (7), but it is not well understood whether or how these differences impact odor perception across species. In this study, we investigate the influence of the OR repertoire on odor perception in humans and fruit flies. Both species exhibit robust responses to odors and cohabitate in most parts of the world (8) but have very different OR repertoires.Most of our knowledge about how an odor percept is experienced by the organism comes from experiments measuring odor perception in humans (9-12) because humans can selfreport their odor experience. Sensory parameters that can be measured in human odor perception by psychophysical techniques include odor intensity, distinguishability, similarity, and sensitivity to an odor. To link OR activation and the odor percept in flies, these parameters and concepts had to be transferred to Drosophila. This was problematic because little is known about how these insects respond behaviorally to odors.Here we report high-throughput behavioral assays that measure odor-evoked responses in single flies with great sensitivity and resolution. We used these assays to probe the sensitivity and receptive range o...

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Olfactory coding in Drosophila larvae investigated by cross-adaptation

Cited by 32 publications

References 33 publications

The impact of odor–reward memory on chemotaxis in larval Drosophila

The impact of odor–reward memory on chemotaxis in larval Drosophila

Behavioral and Synaptic Plasticity Are Impaired upon Lack of the Synaptic Protein SAP47

Influence of odorant receptor repertoire on odor perception in humans and fruit flies

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