Convergence of learned and innate pathways onto descending command systems

• Applicant: Dr. Tomke Stürner
• Subject Area: Molecular Biology and Physiology of Neurons and Glial Cells ; Experimental and Theoretical Network Neuroscience
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 506112062

Animals have to constantly adjust their behaviour to their dynamic environments. Decisions are therefore a result of a complex interplay between evolutionary predisposition and individual experience. Thus far research was focused on two parallel pathways of information processing; innate behavioural responses and learning. Studying these pathways separately obscured the importance of looking at the interaction between them. I want to study how innate and learned neuronal circuits converge, unravelling their connections all the way down to descending neurons projecting to the ventral nerve cord (VNC).In the Drosophila Connectomics Group in Cambridge we use in silico reconstructions of electron microscopy (EM) data to understand the circuits in the Drosophila fly brain. We have recently described the connectivity and morphology of the majority of neurons in the central brain with a focus on the flow of olfactory information. In the Jefferis lab I will identify the circuit motifs downstream of the mushroom body (MB) and the lateral horn (LH), the two higher brain centres principally responsible for learned and innate olfactory behaviour in the Drosophila brain. Additionally, to the information that can be extracted from the EM datasets, a combination of 2-photon calcium imaging, optogenetic stimulation and genetic manipulation of the neurons will allow me to understand the circuit dynamics.The Jefferis lab was the first to identify a complete circuit in which learned (via the MB) and innate pathways converge on specific LH neurons. The expertise in the Jefferis lab, specifically in electrophysiology and olfactory behaviour, will enable me to understand the functionality of the circuit I will identify. Taking advantage of a collaboration with the Drosophila Connectomics Group and the Card lab at Janelia, carrying out a comprehensive reconstruction of all descending neurons connecting brain and VNC, I will be able to link circuit motifs to motor behaviours. Recently two projects in our lab uncovered new components of the MB and LH circuit and genereated new hypotheses on how information is processed by one or the other. I will systematically study the convergence of these two processing areas, which was only tackled sporadically by these works. Additionally, I will be working with the full female and a new full male central nervous system connectome EM dataset. This will help overcome disadvantages of the previously used hemibrain EM dataset, such as missing interactions across the midline and truncated descending neurons. Crucially, I can follow the combined circuit logic in the brain and nerve cord that translates sensory signals into motor behaviour. My goal is to uncover how an animal decides between its innate preference and what it has learned to select a specific behaviour.

• DFG Programme: WBP Fellowship
• International Connection: United Kingdom
• Host: Gregory Jefferis, Ph.D.