Episodic memories—high fidelity memories for events that depend initially on the hippocampus—do not maintain their precision in perpetuity. One benefit of this time-dependent loss of precision is the emergence of event-linked, gist memories that may be used to guide future behaviour in novel, but related situations (i.e., generalization). Models of systems consolidation propose that memory reorganization accompanies this loss of memory precision; however, the locus of this reorganization is unclear. Here we report that time-dependent reorganization of hippocampal engram circuitry is sufficient to explain shifts in memory precision associated with systems consolidation. Using engram labelling tools in mice, we demonstrate that the passage of time rewires hippocampal engram circuits, enabling hippocampal engram neurons to be promiscuously active and guide behaviour in related situations that do not match the original training conditions. Reorganization depends on hippocampal neurogenesis; eliminating hippocampal neurogenesis prevents reorganization and maintains precise, event memories. Conversely, promoting hippocampal neurogenesis accelerates memory reorganization and the emergence of event-linked, gist memories in the hippocampus. Our results suggest that systems consolidation models require updating to account for within-hippocampus reorganization that leads to qualitative shifts in memory precision.
Paul Frankland
Professor Paul Frankland is a senior scientist in the program in Neurosciences & Mental Health at the Hospital for Sick Children in Toronto, Canada. His Josselyn Frankland Lab focuses on modeling cognitive function and dysfunction in mice. In particular, the lab is interested in understanding of systems consolidation, the role of adult neurogenesis in hippocampal memory function and forgetting, the identification and manipulation of memory engrams, and hippocampal memory development.
Paul Frankland holds a Canada Research Chair in Cognitive Neurobiology, and is a member of the Department of Psychology, Department of Physiology and Institute of Medical Science at the University of Toronto. He is a Fellow of the Royal Society of Canada, and a member of the Canadian Institute for Advanced Research (CIFAR) in the program for Child and Brain Development.
Programme
Besides the Donders Lecture at 16:00 there are other opportunities to meet Paul Frankland.
- 10:30–12:30– Masterclass with Paul Frankland
Location: Trigon, Cajal room 02.293 - 12:35–13:00 – ECR Lunch
Location: Trigon, Oval office (register via dondersMT [at] donders.ru.nl, max capacity) - 16:00–17:00 – Donders Lecture by Paul Frankland
Location: Trigon, Red Room
In addition to the lecture, it is possible to request a one-on-one meeting with Professor Frankland between 13:00 and 16:00.
Donders Lectures
In the Donders Lectures series on cognitive neuroscience, outstanding researchers in the field of brain and cognition present their work and ideas to a broad audience of scholars with a diversity of backgrounds, ranging from neuroscience to psychology and linguistics.
