ICLM Journal Club
This Week
29 May 2015
Time: 09:30 am
Place : Gonda 2nd Floor Conference Room
Title: Cell-type-specific sensorimotor processing in striatal projection neurons during goal-directed behavior
Speaker: Tanya Sippy
Speaker Bio: Dr. Sippy started her neuroscience career as an undergraduate at UCLA studying synaptic mechanisms underlying short term plasticity. She then completed her MD and PhD degrees at Columbia University where she became interested how different interneuronal subtypes influence local circuit processing. Afterward, Dr. Sippy completed a postdoctoral fellowship at the EPFL in Lausanne, Switzerland, where she applied the technique of in vivo patch clamp to study the role of striatal neuron subtypes during rewarded behaviors. She is currently at New York University where she is pursuing her residency in the psychiatry research track.
Abstract: A key function of the brain is to interpret incoming sensory information in the context of learned associations in order to guide adaptive behavior. However, the neuronal circuits and causal mechanisms underlying goal-directed sensorimotor transformations remain to be clearly defined for the mammalian brain. The basal ganglia, including the striatum and the dopamine reward system, are thought to be involved in action initiation and selection and their dysfunction is associated with Parkinson’s disease, as well as other brain disorders typically involving sensorimotor deficits. We investigated the role of the striatum in a simple task in which mice learn to lick for water reward in response to a single brief whisker deflection (Sachidhanandam et al., 2013). Mice were trained to detect single deflections of the C2 whisker, and report the deflection by licking a spout to obtain water. Whole-cell recordings revealed strong task-related modulation of membrane potential in the somatosensory striatum. Membrane potential depolarization was significantly larger in hit versus miss trials, correlating with perceptual report. This depolarization has two phases; an early phase corresponding to the sensory stimulation, and a late phase, which we define as the period after the early phase before the animal licks, both of which are larger during hit trials. In addition, in a minority of cells where that fire action potentials, the probability of firing action potentials is higher during hit trials. Interestingly, in response to sensory whisker stimulation, D1R-expressing direct pathway striatal projection neurons transiently depolarized more rapidly and more strongly than D2R-expressing indirect pathway neurons. Transient activity in D1R-expressing neurons could therefore contribute to driving the licking behavior. We tested this hypothesis using optogenetics, finding that transient stimulation of D1R-expressing direct pathway striatal projection neurons, but not D2R-expressing indirect pathway neurons, robustly evoked licking in trained mice. Our results are consistent with learned, goal-directed sensorimotor transformations resulting from enhanced signaling in D1R-expressing striatal projection neurons of the direct ‘go’ pathway.
Background papers: http://www.nature.com/nature/journal/v521/n7552/full/nature14225.html
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)
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