@article {49418, title = {Speed dependent descending control of freezing behavior in Drosophila melanogaster.}, journal = {Nature Communications}, volume = {9}, year = {2018}, month = {2018 Sep 12}, pages = {3697}, abstract = {

The most fundamental choice an animal has to make when it detects a threat is whether to freeze, reducing its chances of being noticed, or to flee to safety. Here we show that Drosophila melanogaster exposed to looming stimuli in a confined arena either freeze or flee. The probability of freezing versus fleeing is modulated by the fly{\textquoteright}s walking speed at the time of threat, demonstrating that freeze/flee decisions depend on behavioral state. We describe a pair of descending neurons crucially implicated in freezing. Genetic silencing of DNp09 descending neurons disrupts freezing yet does not prevent fleeing. Optogenetic activation of both DNp09 neurons induces running and freezing in a state-dependent manner. Our findings establish walking speed as a key factor in defensive response choices and reveal a pair of descending neurons as a critical component in the circuitry mediating selection and execution of freezing or fleeing behaviors.

}, issn = {2041-1723}, doi = {10.1038/s41467-018-05875-1}, author = {Zacarias, Ricardo and Namiki, Shigehiro and Card, Gwyneth M and Vasconcelos, Maria Lu{\'\i}sa and Moita, Marta A} } @article {6270, title = {Essential role of the mushroom body in context-dependent CO2 avoidance in Drosophila.}, journal = {Current Biology}, volume = {23}, year = {2013}, month = {2013 Jul 8}, pages = {1228-34}, abstract = {

Internal state as well as environmental conditions influence choice behavior. The neural circuits underpinning state-dependent behavior remain largely unknown. Carbon dioxide (CO2) is an important olfactory cue for many insects, including mosquitoes, flies, moths, and honeybees [1]. Concentrations of CO2 higher than 0.02\% above atmospheric level trigger a strong innate avoidance in the fly Drosophila melanogaster [2, 3]. Here, we show that the mushroom body (MB), a brain center essential for olfactory associative memories [4-6] but thought to be dispensable for innate odor processing [7], is essential for CO2 avoidance behavior only in the context of starvation or in the context of a food-related odor. Consistent with this, CO2 stimulation elicits Ca(2+) influx into the MB intrinsic cells (Kenyon cells: KCs) in\ vivo. We identify an atypical projection neuron (bilateral ventral projection neuron, biVPN) that connects CO2 sensory input bilaterally to the MB calyx. Blocking synaptic output of the biVPN completely abolishes CO2 avoidance in food-deprived flies, but not in fed flies. These findings show that two alternative neural pathways control innate choice behavior, and they are dependent on the animal{\textquoteright}s internal state. In addition, they suggest that, during innate choice behavior, the MB serves as an integration site for internal state and olfactory input.

}, issn = {1879-0445}, doi = {10.1016/j.cub.2013.05.029}, author = {Br{\"a}cker, Lasse B and Siju, K P and Varela, N{\'e}lia and Aso, Yoshinori and Zhang, Mo and Hein, Irina and Vasconcelos, Maria Lu{\'\i}sa and Grunwald Kadow, Ilona C} } @article {4295, title = {A dimorphic pheromone circuit in Drosophila from sensory input to descending output.}, journal = {Nature}, volume = {468}, year = {2010}, month = {2010 Dec 2}, pages = {686-90}, abstract = {

Drosophila show innate olfactory-driven behaviours that are observed in naive animals without previous learning or experience, suggesting that the neural circuits that mediate these behaviours are genetically programmed. Despite the numerical simplicity of the fly nervous system, features of the anatomical organization of the fly brain often confound the delineation of these circuits. Here we identify a neural circuit responsive to cVA, a pheromone that elicits sexually dimorphic behaviours. We have combined neural tracing using an improved photoactivatable green fluorescent protein (PA-GFP) with electrophysiology, optical imaging and laser-mediated microlesioning to map this circuit from the activation of sensory neurons in the antennae to the excitation of descending neurons in the ventral nerve cord. This circuit is concise and minimally comprises four neurons, connected by three synapses. Three of these neurons are overtly dimorphic and identify a male-specific neuropil that integrates inputs from multiple sensory systems and sends outputs to the ventral nerve cord. This neural pathway suggests a means by which a single pheromone can elicit different behaviours in the two sexes.

}, keywords = {Acetates, Animal, Animals, Arthropod Antennae, Drosophila melanogaster, Drosophila Proteins, Female, Male, Nerve Tissue Proteins, Neuroanatomical Tract-Tracing Techniques, Odors, Oleic Acids, Olfactory Pathways, Olfactory Perception, Pheromones, Physical Stimulation, Sensory Receptor Cells, Sex Characteristics, Sexual Behavior, Transcription Factors}, issn = {1476-4687}, doi = {10.1038/nature09554}, author = {Ruta, Vanessa and Datta, Sandeep Robert and Vasconcelos, Maria Lu{\'\i}sa and Freeland, Jessica and Looger, Loren L and Axel, Richard} }