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Introduction
Publications
Publications (70)
Upon strong and prolonged excitation, neurons can undergo a silent state called depolarization block that is often associated with disorders such as epileptic seizures. Here, we show that neurons in the peripheral olfactory system undergo depolarization block as part of their normal physiological function. Typically, olfactory sensory neurons enter...
Nervous systems continuously receive environmental signals with distinct behavioral meanings. To process ambiguous sensory inputs, neural circuits rely on hubs with compartmentalized synaptic structures. A new study has revealed how, in Drosophila larvae, this architecture with the local release of neuropeptides enables the control of flexible and...
Animals differ in their appearances and behaviors. While many genetic studies have addressed the origins of phenotypic differences between fly species, we are still lacking a quantitative assessment of the variability in the way different fly species behave. We tackled this question in one of the most robust behaviors displayed by Drosophila: chemo...
Tools enabling closed-loop experiments are crucial to delineate causal relationships between the activity of genetically labeled neurons and specific behaviors. We developed the Raspberry Pi Virtual Reality (PiVR) system to conduct closed-loop optogenetic stimulation of neural functions in unrestrained animals. PiVR is an experimental platform that...
Tools enabling closed-loop experiments are crucial to delineate causal relationships between the activity of genetically-labeled neurons and specific behaviors. We developed the Raspberry Pi Virtual Reality system (PiVR) to conduct closed-loop optogenetic stimulation of neural functions in unrestrained animals. PiVR is an experimental platform that...
The neural logic underlying the conversion of non-stationary (dynamic) olfactory inputs into odor-search behaviors has been difficult to crack due to the distributed nature of the olfactory code - food odors typically co-activate multiple olfactory sensory neurons. In the Drosophila larva, the activity of a single olfactory sensory neuron is suffic...
Odorant molecules are detected through the combinatorial activation of ensembles of olfactory sensory neurons. By capitalizing on the numerical simplicity of the Drosophila larval brain, Si et al. (2019) uncover principles constraining the representation of the quality and intensity of olfactory stimuli.
Sensory navigation results from coordinated transitions between distinct behavioral programs. During chemotaxis in the Drosophila melanogaster larva, the detection of positive odor gradients extends runs while negative gradients promote stops and turns. This algorithm represents a foundation for the control of sensory navigation across phyla. In th...
Localizing the sources of stimuli is essential. Most organisms cannot eat, mate, or escape without knowing where the relevant stimuli originate. For many, if not most, animals, olfaction plays an essential role in search. While microorganismal chemotaxis is relatively well understood, in larger animals the algorithms and mechanisms of olfactory sea...
The neurons that connect the brain and ventral nerve cord in fruit flies have been mapped in unprecedented detail.
Tables summarizing the conditions and results of the statistical tests conducted throughout the manuscript.
Animals explore their environment to encounter suitable food resources. Despite its vital importance, this behavior puts individuals at risk by consuming limited internal energy during locomotion. We have developed a novel assay to investigate how food-search behavior is organized in Drosophila melanogaster larvae dwelling in hydrogels mimicking th...
Insects are capable of spectacular achievements through collective behavior, but examples of such behavior in fruit flies are rare. New research indicates that Drosophila larvae engage in coordinated digging to feed collectively.
Drosophila has proven to be an extraordinarily prolific model organism to study the integrated function of neural circuits. This success largely stems from the development of powerful genetic tools to monitor and to manipulate the activity of identified neurons in the fly nervous system. However, establishing causal relationships between the activi...
Mapping brain function to brain structure is a fundamental task for neuroscience. For such an endeavour, the Drosophila larva is simple enough to be tractable, yet complex enough to be interesting. It features about 10,000 neurons and is capable of various taxes, kineses and Pavlovian conditioning. All its neurons are currently being mapped into a...
Larval Drosophila offer a study case for behavioral neurogenetics that is simple enough to be experimentally tractable, yet complex enough to be worth the effort. We provide a detailed, hands-on manual for Pavlovian odor-reward learning in these animals. Given the versatility of Drosophila for genetic analyses, combined with the evolutionarily shar...
A manual for odor-reward learning in larval Drosophila (Supplemental Material 1), example of a table for data analysis (Supplemental Material 2), and an empty table for entering and analyzing one's own data (Supplemental Material 3), in the English language. Versions of this manual in the German, French, Japanese, Spanish, and Italian languages can...
A manual for odor-reward learning in larval Drosophila in the Japanese language. Versions of this manual in the English, German, French, Spanish, and Italian languages can be found in Supplemental Materials 1–3, 4–6, 7–9, 11–13, 14–16, respectively. For a table for data analysis and an empty table for entering and analyzing one's own data, please u...
A manual for odor-reward learning in larval Drosophila (Supplemental Material 4), example of a table for data analysis (Supplemental Material 5), and an empty table for entering and analyzing one's own data (Supplemental Material 6), in the German language. Versions of this manual in the English, French, Japanese, Spanish, and Italian languages can...
A manual for odor-reward learning in larval Drosophila (Supplemental Material 7), example of a table for data analysis (Supplemental Material 8), and an empty table for entering and analyzing one's own data (Supplemental Material 9), in the French language. Versions of this manual in the English, German, Japanese, Spanish, and Italian languages can...
A manual for odor-reward learning in larval Drosophila (Supplemental Material 14), example of a table for data analysis (Supplemental Material 15), and an empty table for entering and analyzing one's own data (Supplemental Material 16), in the Italian language. Versions of this manual in the English, German, French, Japanese, and Spanish languages...
A manual for odor-reward learning in larval Drosophila (Supplemental Material 11), example of a table for data analysis (Supplemental Material 12), and an empty table for entering and analyzing one's own data (Supplemental Material 13), in the Spanish language. Versions of this manual in the English, German, French, Japanese, and Italian languages...
The sense of smell enables animals to react to long-distance cues according to learned and innate valences. Here, we have mapped with electron microscopy the complete wiring diagram of the Drosophila larval antennal lobe, an olfactory neuropil similar to the vertebrate olfactory bulb. We found a canonical circuit with uniglomerular projection neuro...
Detailed observations of larval Drosophila chemotaxis have characterised the relationship between the odour gradient and the runs, head casts and turns made by the animal. We use a computational model to test whether hypothesised sensorimotor control mechanisms are sufficient to account for larval behaviour. The model combines three mechanisms base...
Chemotaxis is a powerful paradigm to investigate how nervous systems represent and integrate changes in sensory signals to direct navigational decisions. In the Drosophila melanogaster larva, chemotaxis mainly consists of an alternation of distinct behavioral modes: runs and directed turns. During locomotion, turns are triggered by the integration...
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 direc...
Chemotaxis is a powerful paradigm to study how orientation behavior is driven by sensory stimulation. Drosophila larvae navigate odor gradients by controlling the duration of their runs and the direction of their turns. Straight runs and wide-amplitude turns represent two extremes of a behavioral continuum. Here we establish that, on average, runs...
How are stereotyped behaviors organized in a simple nervous system? A new study in the Drosophila larva reports that the foraging routine can be performed in the absence of any input from the brain.
The nervous functions of an organism are primarily reflected in the behavior it is capable of. Measuring behavior quantitatively, at high-resolution and in an automated fashion provides valuable information about the underlying neural circuit computation. Accordingly, computer-vision applications for animal tracking are becoming a key complementary...
Tracking and analysis codes of SOS together with a test dataset generated from larvae behaving in an odor gradient. Updated code versions will be uploaded on the website of the Louis lab: http://www.crg.es/matthieu_louis.
(ZIP)
Step-by-step tutorial detailing the use and functionality of
SOS
.
(PDF)
Illustrative movie of posture tracking in flatworms, fruit fly larvae, fishes and mice.
(M4V)
Functional and anatomical dissection of neural circuits is often hindered by the complexity of such systems. With only 10,000 neurons, the central nervous system of the Drosophila larva is at least one order of magnitude simpler than its adult counterpart. Despite this numerical simplicity, the behavioral repertoire of the larva contains a surprisi...
The fruit fly Drosophila larva demonstrates a sophisticated repertoire of behavior under the control of a numerically simple neural system. Historically, the stereotyped responses of larvae to light and odors captivated the attention of biologists. More recently, the sensory receptors responsible for chemosensation, thermosensation, and vision have...
Tracking larval posture at high resolution during navigation.
Or42a single-functional larvae orbiting around an odour source. Playback speed 2x.
Supplementary Figures S1-S3.
Wild type larvae approach to an odour source. Playback speed 2x.
The ability to respond to chemical stimuli is fundamental to the survival of motile organisms, but the strategies underlying odour tracking remain poorly understood. Here we show that chemotaxis in Drosophila melanogaster larvae is an active sampling process analogous to sniffing in vertebrates. Combining computer-vision algorithms with reconstruct...
Learnt predictive behavior faces a dilemma: predictive stimuli will never 'replay' exactly as during the learning event, requiring generalization. In turn, minute differences can become meaningful, prompting discrimination. To provide a study case for an adaptive adjustment of this generalization-discrimination balance, the authors ask whether Dros...
Early in evolution, the ability to sense and respond to changing environments must have provided a critical survival advantage to living organisms. From bacteria and worms to flies and vertebrates, sophisticated mechanisms have evolved to enhance odor detection and localization. Here, we review several modes of chemotaxis. We further consider the r...
Most odors are perceived to have the same quality over a large concentration range, but the neural mechanisms that permit concentration-invariant olfactory perception are unknown. In larvae of the vinegar fly Drosophila melanogaster, odors are sensed by an array of 25 odorant receptors expressed in 21 olfactory sensory neurons (OSNs). We investigat...
Additional Figures S1–S6 and information on genotypes of all Drosophila strains used in this paper.
Protein sequestration occurs when an active protein is sequestered by a repressor into an inactive complex. Using mathematical and computational modeling, we show how this regulatory mechanism (called "molecular titration") can generate ultrasensitive or "all-or-none" responses that are equivalent to highly cooperative processes. The ultrasensitive...
Neural comparisons of bilateral sensory inputs are essential for visual depth perception and accurate localization of sounds in space. All animals, from single-cell prokaryotes to humans, orient themselves in response to environmental chemical stimuli, but the contribution of spatial integration of neural activity in olfaction remains unclear. We i...
Olfactory responses in Drosophila larvae have been traditionally studied in Petri dishes comprising a single peripheral odor source. In this behavioral paradigm, the experimenter usually assumes that the rapid diffusion of odorant molecules from the source leads to the creation of a stable gradient in the dish. To establish a quantitative correlati...
Odorant receptors (ORs) are thought to act in a combinatorial fashion, in which odor identity is encoded by the activation of a subset of ORs and the olfactory sensory neurons (OSNs) that express them. The extent to which a single OR contributes to chemotaxis behavior is not known. We investigated this question in Drosophila larvae, which represent...
Cell fate commitment relies upon making a choice between different developmental pathways and subsequently remembering that choice. Experimental studies have thoroughly investigated this central theme in biology for sex determination. In the somatic cells of Drosophila melanogaster, Sex-lethal (Sxl) is the master regulatory gene that specifies sexu...
Although gene expression can be regulated in a graded or a binary fashion, the majority of eukaryotic genes are either fully activated or not expressed at all in individual cells. This binary response might be an inherent property of many eukaryotic promoters. Analysis of transcription under the control of yeast GAL1 promoter suggests, however, tha...
