Biological Sciences Training Program (BSTP): " 'Joining-the-dots' in Memory"

Dr. David Dupret, Ph.D., Professor of Neuroscience of the Medical Research Council Brain Network Dynamics Unit and Nuffield Department of Clinical Neurosciences at the University of Oxford, will be giving the BSTP seminar. His talk is entitled, "'Joining-the-dots' in memory". The seminar is hosted by the Department of Molecular Psychiatry.

Abstract:

The concerted activity of hippocampal neurons supports information processing with relevance to memory. Continually assimilating new information without corrupting previously acquired ones may be a critical operation performed by the hippocampus, allowing this network to nest multiple, co-existing memories. However, memories typically interact. Notably, 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. 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 recent work that leverages from a parallel cross-species approach to characterize the neural computations underlying inferential reasoning in humans and mice. In so doing, I will discuss the idea that the mammalian hippocampus prospectively represents 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 notably support the idea that short-timescale coactivity amongst hippocampal neurons act as a primary code that supports memory.