RT Journal Article SR Electronic T1 Electrical Stimulation in Hippocampus and Entorhinal Cortex Impairs Spatial and Temporal Memory JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 4471 OP 4481 DO 10.1523/JNEUROSCI.3049-17.2018 VO 38 IS 19 A1 Goyal, Abhinav A1 Miller, Jonathan A1 Watrous, Andrew J. A1 Lee, Sang Ah A1 Coffey, Tom A1 Sperling, Michael R. A1 Sharan, Ashwini A1 Worrell, Gregory A1 Berry, Brent A1 Lega, Bradley A1 Jobst, Barbara C. A1 Davis, Kathryn A. A1 Inman, Cory A1 Sheth, Sameer A. A1 Wanda, Paul A. A1 Ezzyat, Youssef A1 Das, Sandhitsu R. A1 Stein, Joel A1 Gorniak, Richard A1 Jacobs, Joshua YR 2018 UL http://www.jneurosci.org/content/38/19/4471.abstract AB The medial temporal lobe (MTL) is widely implicated in supporting episodic memory and navigation, but its precise functional role in organizing memory across time and space remains elusive. Here we examine the specific cognitive processes implemented by MTL structures (hippocampus and entorhinal cortex) to organize memory by using electrical brain stimulation, leveraging its ability to establish causal links between brain regions and features of behavior. We studied neurosurgical patients of both sexes who performed spatial-navigation and verbal-episodic memory tasks while brain stimulation was applied in various regions during learning. During the verbal memory task, stimulation in the MTL disrupted the temporal organization of encoded memories such that items learned with stimulation tended to be recalled in a more randomized order. During the spatial task, MTL stimulation impaired subjects' abilities to remember items located far away from boundaries. These stimulation effects were specific to the MTL. Our findings thus provide the first causal demonstration in humans of the specific memory processes that are performed by the MTL to encode when and where events occurred.SIGNIFICANCE STATEMENT Numerous studies have implicated the medial temporal lobe (MTL) in encoding spatial and temporal memories, but they have not been able to causally demonstrate the nature of the cognitive processes by which this occurs in real-time. Electrical brain stimulation is able to demonstrate causal links between a brain region and a given function with high temporal precision. By examining behavior in a memory task as subjects received MTL stimulation, we provide the first causal evidence demonstrating the role of the MTL in organizing the spatial and temporal aspects of episodic memory.