Imaging Dendritic and Somatic Activity Underlying Hippocampal Place Coding in Familiar and Novel Evironments

Imaging Dendritic and Somatic Activity Underlying Hippocampal Place Coding in Familiar and Novel Environments

with guest speaker Dr. Jayeeta Basu of New York University Langone Health
This webinar took place on September 25th 2020

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Overview

Join this webinar to learn about a novel preparation which in combination with multiphoton microscopy enables visualization of structures located deep in a brain during mouse exploratory activity. Specifically, this approach allows soma and dendrites to be captured simultaneously in the same plane to uncover the compartment specific organization of spatial representation.

Presenter's Abstract

Imaging Dendritic and Somatic Activity Underlying Hippocampal Place Coding Data

Dendrites of pyramidal neurons integrate different sensory inputs, and non-linear dendritic computations drive feature selective tuning and plasticity. Yet, little is known about how dendrites themselves represent the environment, the degree to which they are coupled to their soma, and how that coupling is sculpted with experience. In order to answer these questions, we developed a novel preparation in which we image soma and connected dendrites in a single plane across days using in vivo two-photon microscopy. Using this preparation, we monitored spatially tuned activity in area CA3 of the hippocampus in head-fixed mice running on a linear track. We identified “place dendrites”, which can stably and precisely represent both familiar and novel spatial environments. Dendrites could display place tuning independent of their connected soma and even their sister dendritic branches, the first evidence for branch-specific tuning in the hippocampus. In a familiar environment, spatially tuned somata were more decoupled from their dendrites as compared to non-tuned somata.  This relationship was absent in a novel environment, suggesting an experience-dependent selective gating of dendritic spatial inputs. We then built a data-driven multicompartment computational model that could capture the experimentally observed correlations. Our model and experimental data indicate that place cells exhibiting branch-specific tuning have more flexible place fields, while neurons with homogenous or co-tuned dendritic branches have higher place field stability. These findings demonstrate that spatial representation is organized in a branch-specific manner within dendrites of hippocampal pyramidal cells. Further, spatial inputs from dendrites to soma are selectively and dynamically gated in an experience-dependent manner, endowing both flexibility and stability to the cognitive map of space.

Speaker

Dr. Jayeeta Basu
Dr. Jayeeta Basu
Assistant Professor in the Neuroscience Institute and the Co-Director of the MD/PhD program at New York University Langone Health
Dr. Basu is an Assistant Professor in the Neuroscience Institute and the Co-Director of the MD/PhD program at New York University Langone Health. Dr. Basu earned her Bachelors degree in Physiology (B.Sc. Hon.’s) from Presidency College in Calcutta, India. In 2002, Jayeeta received a Masters degree in Neuroscience at the International Max Planck Research School, Georg August University in Göttingen, Germany for her research with Dr. Christian Rosenmund and Dr. Erwin Neher on the kinetics of neurotransmitter release. She then completed her Ph.D. at Baylor College of Medicine, where her thesis focused on molecular mechanisms of synaptic vesicle release and short-term plasticity in hippocampal cultured neurons. In 2007, Dr. Basu joined Dr. Steven Siegelbaum’s laboratory at Columbia University for her post-doctoral training. She examined how excitatory and inhibitory circuits interact to shape dendritic integration, timing-dependent plasticity, and learning behavior in the hippocampus. Dr. Basu founded her own lab at New York University Neuroscience Institute in 2015. In her own lab, Dr. Basu aims to identify synaptic and behavioral correlates of learning-related activity in genetically defined circuits of the mammalian hippocampus and entorhinal cortex. Her research combines mouse genetics with electrophysiology, two-photon imaging, and behavior to parse out the synaptic, cellular, and circuit mechanisms of learning.