The Knierim Lab studies the behavioral and cognitive correlates of the hippocampal formation—a brain region that is critical for forming and storing long-term memories. Read more about our research.
Doug GoodSmith and Heekyung Lee Publish Paper in The Journal of Neuroscience
In their continuing investigations of the heterogeneity of response types in the CA3 and DG regions of the hippocampus, Doug and Heekyung published a new study showing that proximal CA3 (CA3c) pyramidal cells and granule cells and mossy cells of the dentate gyrus act as a functional unit that appears to support pattern separation processes in the hippocampus (GoodSmith et al., J Neurosci 2019). Using a classifier that Doug developed for his dissertation, they were able to identify with confidence recordings from each of these anatomically close cell types and showed that they all had similar remapping properties in a local-global cue mismatch manipulation. Importantly, these data reinforce the extremely sparse nature of granule cell firing, and suggest strongly that the majority of all prior published extracellular recordings of DG were mostly from mossy cells, rather than the granule cells that had been assumed.
Welcome New Postdoctoral Fellow Yueqing Zhou and Graduate Student Bharath Krishnan!
Dr. Yueqing Zhou joins the lab from Peking University, where she obtained her Ph.D., and Stanford University, where she was a visiting student. Yueqing will begin experiments using head-mounted miniscopes to track calcium activity in neurons in freely moving rats. Welcome to Baltimore, Yueqing!
Bharath Krishnan, graduate student in Biomedical Engineering, has decided to join the laboratory to pursue his dissertation research. Bharath will begin recordings of the medial entorhinal cortex in our augmented reality “Dome” apparatus, in collaboration with the Cowan lab of Mechanical Engineering. Welcome, Bharath!
Doug GoodSmith Successfully Defends His Ph.D. Thesis
Doug GoodSmith, Ph.D., successfully defended his Ph.D. dissertation on July 17, 2019. His dissertation was titled “Firing correlates and mnemonic functions of dentate gyrus granule cells and mossy cells.” This work was the result of a long collaboration between the Knierim lab and Kim Christian of the lab of Hongjun Song (formerly at Hopkins, now at UPenn). Doug will deliver his public seminar on August 16 at 10:00 am at the Mind/Brain Institute. Congratulations, Doug!
Shan Wang Successfully Defends Her Ph.D. Thesis
Congratulations to Chia-Hsuan (Shan) Wang, Ph.D., who successfully defended her Ph.D. dissertation on May 6, 2019 and presented her public thesis seminar on June 13, 2019. The title of her thesis was “The Cognitive Map and Compartmentalized Space: Neural Representations of Surface Cue Boundaries.” Congratulations, Shan!
Congratulations to Ravi, Manu, and Francesco for Nature paper
March 24, 2019: In collaboration with the LIMBS lab of Noah Cowan (JHU Mechanical Engineering) and the lab of Tad Blair (UCLA), we recently published a paper in Nature showing that the path integration system has a dynamic gain variable that can be recalibrated with experience. We used an augmented reality system to produce a continuous conflict between self-motion cues and visual landmarks, in that rotation of the landmarks produced an illusion that the rat ws running faster or slower than it really was. When we subsequently turned the landmarks off, we showed that CA1 place cells had recalibrated the rate at which they updated the rat’s position based on path integration.
Cheng and Xiaojing publish Science paper
March 24, 2019: Last fall, we published a paper in Science showing that the lateral entorhinal cortex represented the location of the rat in an egocentric framework relative to external locations or items. This result confirms predictions from a model that the LEC encodes the locations of “other” items in the environment from a first-person perspective, as opposed to the MEC, which encodes the position of the “self” in allocentric coordinates. The egocentric coding of LEC is consistent with the notion that the LEC provides the hippocampus with information about the content of an episode, in accordance with the first-person perspective that characterizes episodic memories.
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