@article {49523, title = {Sensorimotor pathway controlling stopping behavior during chemotaxis in the larva.}, journal = {eLife}, volume = {7}, year = {2018}, month = {2018 Nov 22}, abstract = {

Sensory navigation results from coordinated transitions between distinct behavioral programs. During chemotaxis in the 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 the present work, we identified an olfactory descending neuron, PDM-DN, which plays a pivotal role in the organization of stops and turns in response to the detection of graded changes in odor concentrations. Artificial activation of this descending neuron induces deterministic stops followed by the initiation of turning maneuvers through head casts. Using electron microscopy, we reconstructed the main pathway that connects the PDM-DN neuron to the peripheral olfactory system and to the pre-motor circuit responsible for the actuation of forward peristalsis. Our results set the stage for a detailed mechanistic analysis of the sensorimotor conversion of graded olfactory inputs into action selection to perform goal-oriented navigation.

}, issn = {2050-084X}, doi = {10.7554/eLife.38740}, author = {Tastekin, Ibrahim and Khandelwal, Avinash and Tadres, David and Fessner, Nico D and Truman, James W and Zlatic, Marta and Cardona, Albert and Louis, Matthieu} } @article {48642, title = {The Ol1mpiad: concordance of behavioural faculties of stage 1 and stage 3 Drosophila larvae.}, journal = {The Journal of Experimental Biology}, volume = {220}, year = {2017}, month = {2017 Jul 01}, pages = {2452-2475}, abstract = {

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 light-microscopical atlas, and Gal4 strains are being generated to experimentally access neurons one at a time. In addition, an electron microscopic reconstruction of its nervous system seems within reach. Notably, this electron microscope-based connectome is being drafted for a stage 1 larva - because stage 1 larvae are much smaller than stage 3 larvae. However, most behaviour analyses have been performed for stage 3 larvae because their larger size makes them easier to handle and observe. It is therefore warranted to either redo the electron microscopic reconstruction for a stage 3 larva or to survey the behavioural faculties of stage 1 larvae. We provide the latter. In a community-based approach we called the Ol1mpiad, we probed stage 1 Drosophila larvae for free locomotion, feeding, responsiveness to substrate vibration, gentle and nociceptive touch, burrowing, olfactory preference and thermotaxis, light avoidance, gustatory choice of various tastants plus odour-taste associative learning, as well as light/dark-electric shock associative learning. Quantitatively, stage 1 larvae show lower scores in most tasks, arguably because of their smaller size and lower speed. Qualitatively, however, stage 1 larvae perform strikingly similar to stage 3 larvae in almost all cases. These results bolster confidence in mapping brain structure and behaviour across developmental stages.

}, issn = {1477-9145}, doi = {10.1242/jeb.156646}, author = {Almeida-Carvalho, Maria J and Berh, Dimitri and Braun, Andreas and Chen, Yi-chun and Eichler, Katharina and Eschbach, Claire and Fritsch, Pauline M J and Gerber, Bertram and Hoyer, Nina and Jiang, Xiaoyi and Kleber, J{\"o}rg and Kl{\"a}mbt, Christian and K{\"o}nig, Christian and Louis, Matthieu and Michels, Birgit and Miroschnikow, Anton and Mirth, Christen and Miura, Daisuke and Niewalda, Thomas and Otto, Nils and Paisios, Emmanouil and Pankratz, Michael J and Petersen, Meike and Ramsperger, Noel and Randel, Nadine and Risse, Benjamin and Saumweber, Timo and Schlegel, Philipp and Schleyer, Michael and Soba, Peter and Sprecher, Simon G and Tanimura, Teiichi and Thum, Andreas S and Toshima, Naoko and Truman, Jim W and Yarali, Ayse and Zlatic, Marta} } @article {48433, title = {Pavlovian conditioning of larval Drosophila: an illustrated, multilingual, hands-on manual for odor-taste associative learning in maggots.}, journal = {Frontiers in Behavioral Neuroscience}, volume = {11}, year = {2017}, month = {2017 Apr 19}, pages = {45}, abstract = {

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 shared genetic heritage with humans, the paradigm has utility not only in behavioral neurogenetics and experimental psychology, but for translational biomedicine as well. Together with the upcoming total synaptic connectome of the Drosophila nervous system and the possibilities of single-cell-specific transgene expression, it offers enticing opportunities for research. Indeed, the paradigm has already been adopted by a number of labs and is robust enough to be used for teaching in classroom settings. This has given rise to a demand for a detailed, hands-on manual directed at newcomers and/or at laboratory novices, and this is what we here provide. The paradigm and the present manual have a unique set of features: {\textbullet} The paradigm is cheap, easy, and robust; {\textbullet} The manual is detailed enough for newcomers or laboratory novices; {\textbullet} It briefly covers the essential scientific context; {\textbullet} It includes sheets for scoring, data analysis, and display; {\textbullet} It is multilingual: in addition to an English version we provide German, French, Japanese, Spanish and Italian language versions as well. The present manual can thus foster science education at an earlier age and enable research by a broader community than has been the case to date.

}, doi = {10.3389/fnbeh.2017.00045}, author = {Michels, Birgit and Saumweber, Timo and Biernacki, Roland and Thur, Jeanette and Glasgow, Rupert DV and Schleyer, Michael and Chen, Yi-chun and Eschbach, Claire and Stocker, Reinhard F and Toshima, Naoko and Tanimura, Teiichi and Louis, Matthieu and Arias-Gil, Gonzalo and Marescotti, Manuela and Benfenati, Fabio and Gerber, Bertram} } @article {47486, title = {The wiring diagram of a glomerular olfactory system.}, journal = {eLife}, volume = {5}, year = {2016}, month = {2016 May 13}, abstract = {

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 neurons (uPNs) relaying gain-controlled ORN activity to the mushroom body and the lateral horn. A second, parallel circuit with multiglomerular projection neurons (mPNs) and hierarchically connected local neurons (LNs) selectively integrates multiple ORN signals already at the first synapse. LN-LN synaptic connections putatively implement a bistable gain control mechanism that either computes odor saliency through panglomerular inhibition, or allows some glomeruli to respond to faint aversive odors in the presence of strong appetitive odors. This complete wiring diagram will support experimental and theoretical studies towards bridging the gap between circuits and behavior.

}, issn = {2050-084X}, doi = {10.7554/eLife.14859}, author = {Berck, Matthew E and Khandelwal, Avinash and Claus, Lindsey and Hernandez-Nunez, Luis and Si, Guangwei and Tabone, Christopher J and Li, Feng and Truman, James W and Fetter, Richard D and Louis, Matthieu and Samuel, Aravinthan Dt and Cardona, Albert} } @article {46835, title = {Dynamical feature extraction at the sensory periphery guides chemotaxis.}, journal = {eLife}, volume = {4}, year = {2015}, month = {2015 Jun 16}, abstract = {

Behavioral strategies employed for chemotaxis have been described across phyla, but the sensorimotor basis of this phenomenon has seldom been studied in naturalistic contexts. Here, we examine how signals experienced during free olfactory behaviors are processed by first-order olfactory sensory neurons (OSNs) of the Drosophila larva. We find that OSNs can act as differentiators that transiently normalize stimulus intensity-a property potentially derived from a combination of integral feedback and feed-forward regulation of olfactory transduction. In olfactory virtual reality experiments, we report that high activity levels of the OSN suppress turning, whereas low activity levels facilitate turning. Using a generalized linear model, we explain how peripheral encoding of olfactory stimuli modulates the probability of switching from a run to a turn. Our work clarifies the link between computations carried out at the sensory periphery and action selection underlying navigation in odor gradients.

}, issn = {2050-084X}, doi = {10.7554/eLife.06694}, author = {Schulze, Aljoscha and Gomez-Marin, Alex and Rajendran, Vani G and Lott, Gus and Musy, Marco and Ahammad, Parvez and Deogade, Ajinkya and Sharpe, James and Riedl, Julia and Jarriault, David and Trautman, Eric T and Werner, Christopher and Venkadesan, Madhusudhan and Druckmann, Shaul and Jayaraman, Vivek and Louis, Matthieu} } @article {46743, title = {Role of the subesophageal zone in sensorimotor control of orientation in Drosophila larva.}, journal = {Current Biology}, volume = {25}, year = {2015}, month = {2015 May 6}, pages = {1448-60}, abstract = {

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 of temporal changes in the intensity of the stimulus. Upon completion of a turning maneuver, the direction of motion is typically realigned toward the odor gradient. While the anatomy of the peripheral olfactory circuits and the locomotor system of the larva are reasonably well documented, the neural circuits connecting the sensory neurons to the motor neurons remain unknown. We combined a loss-of-function behavioral screen with optogenetics-based clonal gain-of-function manipulations to identify neurons that are necessary and sufficient for the initiation of reorientation maneuvers in odor gradients. Our results indicate that a small subset of neurons residing in the subesophageal zone controls the rate of transition from runs to turns-a premotor function compatible with previous observations made in other invertebrates. After having shown that this function pertains to the processing of inputs from different sensory modalities (olfaction, vision, thermosensation), we conclude that the subesophageal zone operates as a general premotor center that regulates the selection of different behavioral programs based on the integration of sensory stimuli. The present analysis paves the way for a systematic investigation of the neural computations underlying action selection in a miniature brain amenable to genetic manipulations.

}, issn = {1879-0445}, doi = {10.1016/j.cub.2015.04.016}, author = {Tastekin, Ibrahim and Riedl, Julia and Schilling-Kurz, Verena and Gomez-Marin, Alex and Truman, James W and Louis, Matthieu} }