ICLM Journal Club
This Week
20 February 2015 YOUNG INVESTIGATOR SEMINAR
Time: 09:30 am
Place : Gonda 2nd Floor Conference Room
Title: Co-allocation of neural ensembles links different memories across time
Speaker: Denise Cai (Silva Lab) While there have been significant advances in the understanding of the mechanisms underlying the storage of single memories, real-world memories, however, involve the integration of multiple memories across time, with one memory affecting how another is processed and stored. Recent studies find that virally increasing neuronal excitability changes the probability of that neuron to participate in a memory trace (i.e. cellular allocation). This leads to the prediction that the induction of one memory will trigger a time-dependent increase in excitability that will then affect the cellular allocation of a subsequent memory, thus sharing a neural ensemble will link the two memories across time. Using in vivo calcium imaging (with miniaturized fluorescent microscopes in freely behaving mice), the TetTag transgenic system, we found that a given contextual memory can affect which CA1 neurons store a subsequent contextual memory 5 hours later (when there is increased excitability in the neurons participating in the first memory) but not 7 days later. The CA1 neuronal ensembles representing each of the two memories co-allocate significantly (>20% above chance) when they are separated by 5 hours but not by 7 days. Interestingly, we found evidence that the co-allocation between cellular ensembles also led to contextual linking as fear from a context paired with shock was generalized to a non-shocked context when the two episodes were spaced by 5 hours, but not by 7 days. We found enhanced behavioral memory for the second episode, when spaced 5 hours from the first episode but not when spaced by 7 days, presumably due to the transient increase in excitability. Finally, our studies in older mice, known to have decreased excitability in CA1, revealed a disruption of co-allocation processes that link memories across time. Altogether, these results provide important insights into how intrinsic changes in excitability can serve to temporally and contextually link multiple memories.
Background Papers: Silva et al., 2009 Rogerson et al., 2014
About Us
Introduction
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.
Current Organizers:
Walt Babiec (O'Dell Lab) & Helen Motanis (Buonomano Lab)
Current Faculty Advisor:
Past Organizers:
i) Anna Matynia(Aug 2004 - Jun 2008) (Silva Lab)
ii) Robert Brown (Aug 2008 - Jun 2009) (Balleine Lab)
iii) Balaji Jayaprakash (Aug 2008 - Nov 2011) (Silva Lab)
iv) Justin Shobe & Thomas Rogerson (Dec 2011 - June 2013) (Silva Lab)
Wiki Newbies
Consult the User's Guide for information on using the wiki software.
