Difference between revisions of "ICLM Journal Club"
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Revision as of 23:12, 17 October 2017
This Week - 13 October 2017 (9:30 a.m., Gonda 2nd Floor Conference Room)
Speaker: Nazim Kourdougli
Title: Amygdala-Cortical Circuits in reward value encoding and retrieval
Abstract: The value of an anticipated reward is a key element in the decision to engage in its pursuit. This value is encoded when the reward is experienced in a relevant motivational state. The basolateral amygdala (BLA) is required for this incentive learning process, but how it achieves this function within the broader reward-seeking circuitry is unknown. Moreover, it remains unclear whether the BLA participates in retrieving value information for guiding reward seeking. The BLA receives dense glutamatergic innervations from several cortical regions, including the orbitofrontal cortex (OFC), a region also implicated in value attribution. We first examined BLA excitatory input activity using electroenzymatic biosensors to make near-real time measurements of BLA glutamate concentration changes during value encoding (experience with a food reward in novel hungry state) and a subsequent reward-seeking test. We found that glutamate is transiently released in the BLA during reward value encoding and immediately preceding bouts of subsequent value-guided reward-seeking activity, but only if rats had previously encoded and, therefore, retrieved the value of the anticipated reward to guide actions. Using a pharmacological approach, BLA NMDA receptors were found to be necessary for encoding a positive change in reward value, and both AMPA and NMDA receptors were necessary for subsequent value-guided reward seeking. We next sought to identify the specific cortical afferent contributors to these input signals. Given the anatomical and functional distinctions within the OFC, we specifically targeted either the lateral or medial OFC using chemogenetic and optogenetic approaches to bidirectionally modulate the activity of these projections to the BLA. Activity in lateral OFC to BLA projections was found to be both necessary for and sufficient to enhance encoding of a positive change in reward value, but not for subsequent retrieval of this information for online decision making. Conversely, projections from the medial OFC were not required for incentive learning, but were found to be necessary for retrieval of reward value and sufficient to enhance value-guided reward seeking actions. These data demonstrate that the BLA participates in both the encoding and retrieval of reward value via excitatory input from the OFC and that there is a double dissociation of the contribution of lateral vs. medial OFC to BLA projections to encoding vs. retrieval, respectively. These data have important implications for the myriad diseases marked by maladaptive reward valuation and decision-making.
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:
Shonali Dhingra & Helen Motanis
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)
v) Walt Babiec (O'Dell Lab) (2013-2014)
vi) Walt Babiec (O'Dell Lab) & Helen Motanis (Buonomano Lab) (2014-2017)
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