LIN Seminar: Alex Keinath & Dennis Sparta
September 21, 2023
4:00 PM - 5:00 PM
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Please join us on September 21, 2023 for a joint seminar by Dr. Dennis Sparta and Dr. Alexandra Keinath (LIN Faculty)
Alex Keinath will present "Quantitative comparison of spatial codes within and beyond rodent hippocampus with representational similarity analysis"
Abstract: Decades of theoretical and empirical work have implicated the hippocampus as instantiating some form of a spatially-tuned cognitive map which in turn supports episodic memory. Yet recent work is prompting a re-evaluation of these theories. On one hand, neural signatures of cognitive mapping are being found throughout the rodent brain including in regions not traditionally associated with space, while the evidence of cognitive mapping in primate hippocampus is mixed. On the other hand, tests of competing cognitive mapping theories have been limited in scope and/or qualitative in nature, making it difficult to apply such theories with precision. All in all, there is a mounting need to quantitatively compare spatial codes across brain regions, species, and models. To meet this need, here we introduce a novel paradigm leveraging a representational similarity framework to quantitatively compare such codes. To this end, we first recorded large hippocampal populations as freely behaving mice engage in this paradigm across one month of imaging. Next, we use these data to benchmark models of cognitive mapping. Specifically, we show that these data characterize novel dynamics with high precision, effectively constrain viable model parameterizations, and are capable of distinguishing between competing models. Lastly, we use immersive virtual reality to characterize human spatial memory in a behavioral version of this paradigm. Comparison of preliminary data from this experiment to the mouse hippocampal data highlights interesting similarities and differences across species, which we will leverage in the future. Altogether, this work marks a first step towards quantitative comparison of spatial codes across species and models, setting the stage for experiments to come.
Dennis Sparta will present "Dissecting extended amygdala circuits in aberrant motivated behavior"
Abstract: The co-morbidity of anxiety and dysfunctional reward processing in illnesses such as alcohol and/or substance use disorder suggests that common neural circuitry contributes to these disparate neuropsychiatric symptoms. The extended amygdala, including the central amygdala (CeA) modulates fear, anxiety, reward, and aversion, thus providing a candidate neural substrate that is involved in integrating diverse emotional states. However, the CeA is extremely heterogenous, containing many different neuronal subtypes, making it difficult to study their exact contributions to behavior. In the Sparta laboratory, we use multiple contemporary circuit mapping techniques in mice including electrophysiology, optogenetics, chemogenetics, and advanced microscopy, to identify, record, and manipulate genetically identical neurons and circuits within these structures in order to ascertain their role in controlling motivational states. Here, I will discuss the development of a binge ethanol drinking model in mice and how distinct CeA corticotropin releasing factor (CRF) neurons encode different aspects of this behavior including intoxication and withdrawal. Using slice electrophysiology, we will show how binge ethanol drinking alters synaptic drive onto CeA CRF neurons. Finally, I will discuss how binge ethanol drinking induces microglia induced neuroinflammation within the CeA and can be reduced by administration of minocycline, a potent anti-inflammatory compound. Taken together, these data may provide insight for the development of new treatment strategies to normalize maladaptive behaviors.
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