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CCN Brown Bag Series: Sean Polyn

Wednesday, September 03, 2014,

  • Location: Wilson Hall • 111 21St Ave S • Nashville, TN 37240
  • Room: 115

The Cognition and Cognitive Neuroscience (CCN) program presents Sean Polyn, Department of PsychologyVanderbilt University

12:10 p.m. Room 115, Wilson Hall

Neural activity in the medial temporal lobe revealing the fidelity of mental time travel

Neural circuitry in the medial temporal lobe (MTL) is critically involved in retrieving the details of past experience. Different neuroscientific theories propose that the MTL supports memory of the past by successfully retrieving previously encoded episodic information, as well as by reactivating a temporal code specifying the position of a particular event within the episode. However, the computational mechanisms supporting these abilities are underspecified. To test the computations supported by MTL subregions that are sufficient to facilitate mental time travel, we developed a computational model that linked blood oxygen level-dependent (BOLD) signal to cognitive operations, allowing us to predict human performance in a memory search task. Under this model, signal from parahippocampal cortex signals how strongly one reactivates the context of a retrieved memory, allowing the model to predict whether the next memory will correspond to a nearby moment in the study episode. Signal from perirhinal cortex, in contrast, indicates the successful retrieval of item information, allowing the model to predict whether the participant will continue to report remembered materials. Hippocampal signal reflects both processes, consistent with theories that this region binds item and context information together to form episodic memories. These findings are consistent with modern theories describing complementary roles for the hippocampus and surrounding parahippocampal and perirhinal cortices during the retrieval of episodic memories, shaping how humans revisit the past.