Our brain can be viewed as a large-scale network consisting of smaller, interconnected neural circuits. These circuits operate through complex interactions to process signals, such as environmental cues and internal feedback. The primary connections between such networks consist of direct, synaptic interactions between individual neurons. In addition, however, every neuron is subject to modulation via so called neuromodulators, which connect neural networks both locally and over great distances. This modulation can strengthen or weaken synaptic connections and therefore allows connectivity changes within the system. The ability of neural networks to process multiple signals, whether they are synaptic or modulatory, permits flexibility in the nervous system, enabling adaption to ever-changing circumstances.

To gain deeper insight into how this complex though flexible system functions, we need to further our understanding of the multiple layers shaping neural interactions. With its powerful genetic toolkit, the model organism Drosophila melanogaster can be exploited to study synaptic connectivity. This may be achieved by tracing individual neurons and synapses to establish a connectome. However, to fully understand the dynamics and connectivity of neural networks, considering the modulation of neural circuits is equally important. For this reason, Isabella focuses on the modulation of neurosecretory cells in Drosophila melanogaster and how their activity patterns are influenced by other neuromodulators. To this end, Isabella is combining optogenetic tools with calcium imaging and whole-cell patch-clamp recordings. Comparing findings on a single-cell level measured via patch-clamp recording to the populational level dynamics assessed via calcium imaging will contribute to a better understanding of reciprocal modulation as well as systemic neuromodulation.

Isabella holds a B.Sc. in Biotechnology from the Technical University of Berlin, where she focused on addiction behavior in Drosophila during her Bachelor’s Thesis in David Owald’s Lab. Now, she is pursuing her Master’s degree in the Fast Track Program FOKUS Life Sciences at the University of Würzburg, and will complete her Master’s Thesis in the Ache Lab.

Our brains integrate many kinds of sensory information to create the appropriate behavioral output in a wide variety of situations. Sensory systems constantly integrate external and internal cues and relay the information to motor systems to drive behavior. In the human brain, a diverse number of circuits and around 90 billion neurons are responsible for these computations. In flies, like Drosophila melanogaster, with less than one million neurons and a brain the size of a poppy seed, the situation is thought to be simpler. Nevertheless, flies are capable of a range of complex behaviors, including navigation and learning. This complex array of behaviors, the small number of neurons, and the genetic toolkit available in Drosophila make them a great model system for the investigation of sensorimotor pathways controlling specific behaviors.

At present, Aleyna is working on her Master‘s Thesis, in which she is studying the integration of visual and mechanosensory inputs by a descending command-type neuron in Drosophila. To this end, she presents visual stimuli using an LED arena and mechanosensory stimuli via air puffs while performing in vivo whole-cell patch-clamp recordings in behaving flies. Thus, she aims to explore how populations of descending neurons integrate multimodal sensory cues to drive behavior.

Aleyna is from Turkey and she graduated with honors from a B.Sc program in Molecular Biology and Genetics at  Bogazici University, Istanbul. She is now doing her M.Sc at the JMU Würzburg in the Graduate School of  Life Sciences FOKUS program. Her experience so far also includes electrophysiology and immunohistochemistry in mouse brain slices. 

Although the brain contains the essence of what makes us human, we still know very little about the complex processes going on inside of it – we don’t even notice much of the work the brain does for us on a daily basis. One of the reasons why I decided to study biology was because of my fascination with this organ and its secrets. A good approach towards understanding complex processes and systems is to start with less complex systems, try to understand those, and then extrapolate the findings to try and grasp general principles.

Drosophila has proven to be a great model system for understanding brains. Flies have a numerically less complex nervous system than vertebrates but are still capable of producing a broad spectrum of adaptive behavior. Furthermore, Drosophila is an easy-to-handle genetically tractable lab animal which greatly facilitates our research. With the help of this model system, we can dive in and understand a little bit more about what I find to be one of the most fascinating feature of the brain: its flexibility. The brain must adapt to the ever-changing demands of the environment and its own body. Moreover, sensory inputs from the environment and the internal state of the animals must be integrated to select and perform adequate behaviors in different situations. For example, flying to a perceived food source and subsequently feeding. Afterwards, the ingested food must be digested and processed, all of which is controlled by neuronal networks. It would therefore be beneficial if sensory input from the environment, such as an appetitive food odor in case the animal is hungry, would activate signaling cascades to prepare the animal’s digestive system even before it starts feeding. 

For my bachelor’s thesis I investigated whether specific sensory inputs lead to anticipatory changes in modulatory brain neurons and, ultimately, behavioral adaptions to different external conditions. After finishing my thesis, I took the opportunity to stay in the lab as a student assistant to continue working on the project, while completing my Master of Science at the University of Würzburg.

Animal behavior needs to be flexible and adaptive to changes in the environment, but behavioral decisions also need to take changing internal demands into account. Environmental factors such as incoming predators can trigger escape behaviors, for example, while internal demands, like hunger, can increase food-searching behavior. To achieve appropriate behavioral selection under various, complex conditions, multiple sensory inputs must be received and integrated by neuronal circuits in the brain in a context-dependent manner. 

Stefan is studying this context-dependent integration of sensory stimuli by neural circuits and the resulting behavioral responses. He is focusing on descending neurons, which play a major role in eliciting behaviors by controlling and modulating activity pattens in motor networks of the ventral nerve cord (the analogue to the vertebrate spinal cord). In certain behaviors, such as landing, these neurons are gated by the behavioral state of the fly. If the fly is in a state where landing is inappropriate the neurons controlling landing are decoupled from visual stimuli thereby preventing undesired behavioral responses. To elucidate whether state-dependent modulation of descending neurons is a general mechanism mediating action selection, and how this modulation is achieved, Stefan uses in vivo whole-cell patch clamp recordings combined with optogenetic tools and behavioral analysis. 

Stefan holds a B.Sc in Applied Biology from the University of Applied Sciences Bonn Rhein-Sieg and a M.Sc in Life and Medical Sciences from the University Bonn. He did his PhD in the group of Prof. Kittel at the Institute of Animal Physiology. His thesis focused on metabotropic mechanosensation in chordotonal organs of Drosophila larvae.

Tanja is a visiting Professor from Florida Atlantic University. We’re collaborating on a project that investigates the role of G protein-coupled receptors in regulating neuronal activity which, according to Tanja, makes us finally do ‘proper mechanistic neuroscience’. Apart from sharing her expertise on sub-cellular signaling pathways, Tanja helps us push our fly game.

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