Seminar: Handling multiple memories in the hippocampus network by Prof. David Dupret

David Dupret completed his Ph.D. in Neuroscience and Neuropharmacology at the Institute François Magendie (INSERM, University of Bordeaux, France) for which he received the French Neuroscience Association’s 2007 Ph.D. Year Prize. David has also held an ‘Agrégation‘ Biological and Earth Sciences (Ministry of Education, France) since 2000. He joined the group of Prof. Jozsef Csicsvari at the MRC Anatomical Neuropharmacology Unit in September 2007 as a Visiting Fellow, successively funded by the ‘Institute of France‘ (Foundation Louis D. Research Fellowship 2007) and the International Brain Research Organisation (IBRO Research Fellowship 2008). In 2009, David was appointed as a MRC Investigator Scientist, and joined St Edmund Hall College as a Fellow in Neuroscience. David was then appointed to a MRC Senior Scientist position in 2011, and promoted to tenured MRC Programme Leader in 2014. In 2016, David was named a Scholar of the FENS-Kavli Network of Excellence and, in 2018, received the Boehringer Ingelheim-FENS 2018 Research Award for his work on dynamics of neuronal assemblies in memory processes. He was awarded the title of Professor of Neuroscience by the University of Oxford in 2020. The general aim of David’s research programme is to investigate the circuit-level mechanisms of memory-guided behaviour.

The concerted activity of hippocampal neurons supports information processing with relevance to memory. However, while assimilating new information without corrupting previously acquired ones is critical, learning and memory nevertheless interact: prior knowledge can proactively influence ongoing learning, and new information can retroactively modify pre-existing memories. In this talk, I will first present recent work investigating some of the neuronal operations that enable to incorporate new experiences in the hippocampus network, segregating them as discrete traces while enabling their interaction. By embedding coactive neurons in mathematical graphs, this work describes that mnemonic information spans multiple operational axes in the mouse hippocampus network. Notably, high activity principal cells form the core of each memory along a first axis, segregating spatial contexts and novelty. Low activity cells join coactivity motifs across behavioural events and enable their crosstalk along two other axes. I will then discuss how discrete, co-existing memories can be stitched together beyond direct experience. I will present recently published work that leverages from a parallel cross-species approach to characterize the neural computations underlying inferential reasoning in humans and mice. With this work, I will describe that the mammalian hippocampus can prospectively represent learned associations necessary for inference at the time of choice, to then “join the dots” between memory items that were not directly experienced together but are logically related. Altogether, these findings will support the idea of continuous re-structuring and interaction of hippocampal memories in the “network activity space”.