Tihana Jovanic

Paris Saclay Institute of Neuroscience

Nervous systems have the ability to select appropriate actions and action sequences in response to sensory cues. The circuit mechanisms by which nervous systems achieve choice, stability and transitions between behaviors are still incompletely understood. To identify neurons and brain areas involved in controlling these processes, we combined a lar...

To study neural circuits underlying decisions, the model organism used for that purpose has to be simple enough to be able to dissect the circuitry neuron by neuron across the nervous system and in the same time complex enough to be able to perform different types of decisions. Here, I lay out the case: (1) that Drosophila larva is an advantageous...

Interneurons (INs) coordinate motoneuron activity to generate appropriate patterns of muscle contractions, providing animals with the ability to adjust their body posture and to move over a range of speeds. In Drosophila larvae several IN subtypes have been morphologically described and their function well documented. However, the general lack of m...

Animals use sensory information to move toward more favorable conditions. Drosophila larvae can move up or down gradients of odors (chemotax), light (phototax), and temperature (thermotax) by modulating the probability, direction, and size of turns based on sensory input. Whether larvae can anemotax in gradients of mechanosensory cues is unknown. F...

Small animals use sensory information to navigate their environment in order to reach more favorable conditions. in gradients of light, temperature, odors and CO 2 , Drosophila larvae alternate periods of runs and turns, regulating the frequency size and direction of turns, to move in a favorable direction. Whether larvae use the same strategies wh...

Nervous systems across the animal kingdom have the ability to select appropriate actions and sequences of actions in response to sensory cues. The circuit mechanisms by which nervous systems achieve choice, stability and transitions between behaviors are still incompletely understood. To identify neurons and brain areas involved in controlling thes...

Even a simple sensory stimulus can elicit distinct innate behaviors and sequences. During sensorimotor decisions, competitive interactions among neurons that promote distinct behaviors must ensure the selection and maintenance of one behavior, while suppressing others. The circuit implementation of these competitive interactions is still an open qu...

Even a simple sensory stimulus can elicit distinct innate behaviors and sequences. During sensorimotor decisions, competitive interactions among neurons that promote distinct behaviors must ensure the selection and maintenance of one behavior, while suppressing others. The circuit implementation of these competitive interactions is still an open qu...

Activation induced cytidine deaminase (AID) is an essential enzyme for class switch recombination (CSR) and somatic hypermutation (SHM) during secondary immune response. Mutations in the AICDA gene are responsible for Hyper IgM 2 syndrome where both CSR and SHM or only CSR are affected. Indeed, triggering either of the two mechanisms requires the D...

All organisms react to noxious and mechanical stimuli but we still lack a complete understanding of cellular and molecular mechanisms by which somatosensory information is transformed into appropriate motor outputs. The small number of neurons and excellent genetic tools make Drosophila larva an especially tractable model system in which to address...

Movie of larval reaction to air current. Movie of contours of larvae in the air current assay obtained with the MWT software. Inside each contour the spine is shown as a white line divided into 10 segments. Green triangle marks the onset and duration of a 6.5 m/s air current stimulus. White arrows point to the larvae that show clear hunching. Prior...

Summary of results from the vibration experiments. (CSV)

Summary of results from the air-current experiments. (CSV)

Summary of results from the ChR2 experiments. (CSV)

Movie of larval reaction to noxious heat. Movie of contours of larvae in the noxious heat assay obtained with the MWT software. Inside each contour the spine is shown as a white line divided into 10 segments. Short white lines perpendicular to the spine are used to determine the width of the animal. Green triangle marks the onset of a 1 sec long IR...

Larvae roll to the let when the noxious heat stimulus is applied to the left side of the body. Movie of contours of larvae as above. Green triangle marks the onset of a 1 sec long noxious heat stimulus. In this experiment the black dot was painted on the left side of the larvae. In response to stimulus onset larvae strongly bend and then roll. The...

Movie of larval reaction to vibration. Movie of contours of larvae in the vibration assay obtained with the MWT software. Inside each contour the spine is shown as a white line divided into 10 segments. Green triangle marks the onset of a 30 sec long 1000 Hz 2 V vibration stimulus. White arrows point to the larvae that show clear hunching. Prior to...

Summary of results from the nociception experiments. (CSV)

Movie from which the stills in Figure 2a were taken. Movie of the contour of a larva as above. The black dot is painted on the back of this animal. Just prior to stimulation the larva crawled and performed a left head cast. In response a 1 sec long IR laser pulse that induced the noxious heat stimulus the larva bent and rolled and then escape crawl...

In the absence of stimulation larvae crawl and occasionally head cast. Movie of contours of larvae as above. In the absence of stimulation larvae crawl and occasionally head cast and change direction of crawling. When two larvae touch each other they cannot be tracked and their traces are terminated. (AVI)

Movie of the GCaMP3 imaging in ch neurons response to vibration. A movie of Ca2+ signals visualized with GCaMP3 in the lch1-5 neurons of one abdominal hemisegment (A4). White circle in the top right hand corner marks stimulus onset and duration. (AVI)

Analysis of behaviors of model organisms has a number of applications, particularly to determination of the function of genes and neurons. Drosophila larva is an especially convenient model system for this kind of study because of availability of powerful genetic analysis tools and of automated tracking software that allows high-throughput recordin...

Somatic hypermutation (SHM) of immunoglobulin genes is currently viewed as a two step process initiated by the deamination of deoxycytidine (C) to deoxyuridine (U), catalysed by the activation induced deaminase (AID). Phase 1 mutations arise from DNA replication across the uracil residue or the abasic site, generated by the uracil-DNA glycosylase,...