ICLM Journal Club
This Week - 23 October 2020 (9:30 a.m., via Zoom)
Speaker: Erica Ramirez
Title: “A hypothalamic novelty signal modulates hippocampal memory”
Abstract: The ability to recognize information that is incongruous with previous experience is critical for survival. Novelty signals have therefore evolved in the mammalian brain to enhance attention, perception and memory. Although the importance of regions such as the ventral tegmental area and locus coeruleus in broadly signalling novelty is well-established, these diffuse monoaminergic transmitters have yet to be shown to convey specific information on the type of stimuli that drive them. Whether distinct types of novelty, such as contextual and social novelty, are differently processed and routed in the brain is unknown. Here we identify the supramammillary nucleus (SuM) as a novelty hub in the hypothalamus. The SuM region is unique in that it not only responds broadly to novel stimuli, but also segregates and selectively routes different types of information to discrete cortical targets—the dentate gyrus and CA2 fields of the hippocampus—for the modulation of mnemonic processing. Using a new transgenic mouse line, SuM-Cre, we found that SuM neurons that project to the dentate gyrus are activated by contextual novelty, whereas the SuM–CA2 circuit is preferentially activated by novel social encounters. Circuit-based manipulation showed that divergent novelty channelling in these projections modifies hippocampal contextual or social memory. This content-specific routing of novelty signals represents a previously unknown mechanism that enables the hypothalamus to flexibly modulate select components of cognition.
Relevant Paper(s): https://www.nature.com/articles/s41586-020-2771-1
The Integrative Center for Learning and Memory (ICLM) is a multidisciplinary center of UCLA labs devoted to understanding the neural basis of learning and memory and its disorders. This will require a unified approach across different levels of analysis, including;
1. Elucidating the molecular cellular and systems mechanisms that allow neurons and synapses to undergo the long-term changes that ultimately correspond to 'neural memories'.
2. Understanding how functional dynamics and computations emerge from complex circuits of neurons, and how plasticity governs these processes.
3. Describing the neural systems in which different forms of learning and memory take place, and how these systems interact to ultimately generate behavior and cognition.
History of ICLM
The Integrative Center for Learning and Memory formally LMP started in its current form in 1998, and has served as a platform for many interactions and collaborations within UCLA. A key event organized by the group is the weekly ICLM Journal Club. For more than 10 years, graduate students, postdocs, principal investigators, and invited speakers have presented on topics ranging from the molecular mechanisms of synaptic plasticity, through computational models of learning, to behavior and cognition. Dean Buonomano oversees the ICLM journal club with help of student/post doctoral organizers. For other events organized by ICLM go to http://www.iclm.ucla.edu/Events.html.
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