Development of neuronal circuitry: How bottom-up and top-down projections find each other in the developing rhinophore ganglia of Berghia stephanieae

• Applicant: Dr. Simone Rey
• Subject Area: Evolutionary Cell and Developmental Biology (Zoology) ; Developmental Biology ; Developmental Neurobiology
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 572387213

Behaviour is encoded in the wiring diagram of the nervous system. A major question in neuroscience is whether we can decode the wiring diagram to understand behaviour. For many years, neuroscience lacked a technique to resolve full wiring diagrams with synaptic resolution. Advances in volume electron microscopy have mostly overcome this issue; at least in small creatures. The smaller the volume of the nervous system, the more individual data sets can be collected. That makes the generation of connectomes across multiple developmental stages of small animals feasible. Tracking the development of the wiring diagram is a powerful approach to identify connectivity patterns and hence, grasp the computational mechanisms underlying behaviour. In this project, I intend to address the fundamental question how neuronal circuits that integrate bottom-up and top-down sensory information come into being. I propose that the rhinophore ganglia in the sea slug Berghia stephanieae pose an excellent model to observe the building of neuronal circuits using connectomics. First, nervous system development in molluscs resembles vertebrate nervous system development. Second, Berghia juveniles are very small. Third, the rhinophores are important sensory organs, equivalent to mammalian eyes. The rhinophores are not yet developed when Berghia hatches. Therefore, the rhinophores and their associated ganglia are easily accessible for experiments throughout their development. I have already established a sample processing pipeline for Berghia juveniles to approach the endeavour of developmental connectomics. In my first aim, I will generate two early-stage juvenile Berghia volume electron microscopic data sets based on high-pressure frozen and freeze-substituted samples. In aim 2, I will map the wiring diagram of both early-stage Berghia juveniles with the help of machine-learning tools. Lastly, I will quantitatively describe the two juvenile Berghia rhinophore connectomes and compare the collected metrics to one another and the already existing adult Berghia rhinophore ganglion connectome in aim 3. Ultimately, I will be able to draw conclusions about neuronal circuit formation. Here, I will focus on the development of neuronal circuits that integrate sensory input from the rhinophore periphery and putative modulatory control from central ganglia.

• DFG Programme: WBP Fellowship
• International Connection: USA
• Host: Professor Jeff W. Lichtman, Ph.D.