Investigating heading representation in the zebrafish interpeduncular nucleus (2024 FENS-Kavli network of excellence PhD thesis prize).

The brain's ability to integrate sensory and motor information allows us to maintain a sense of orientation in space, a process in which head-direction cells play a key role. While these neurons have been studied extensively in mammals, their presence and function in non-mammalian species remain less understood. Here, I summarize the research work for my PhD thesis, where we explore the interpeduncular nucleus (IPN) in zebrafish, a lesser known brain region, using whole-brain electron microscopy and calcium imaging techniques. We identified a novel population of unipolar neurons, with their activity exhibiting a dynamic, rotational pattern during head movements, even in the absence of sensory cues. This population mirrors the functionality of head-direction cells observed in mammals, suggesting a conserved mechanism for spatial orientation across vertebrates. Our findings reveal the potential of the zebrafish IPN as a vertebrate model for studying ring attractor networks, a theoretical framework previously used to explain head-direction cell activity. These results pave the way for future research on how motor and sensory signals converge in the vertebrate brain to maintain spatial orientation.