PT  - JOURNAL ARTICLE
AU  - Abhinav Goyal
AU  - Jonathan Miller
AU  - Andrew J. Watrous
AU  - Sang Ah Lee
AU  - Tom Coffey
AU  - Michael R. Sperling
AU  - Ashwini Sharan
AU  - Gregory Worrell
AU  - Brent Berry
AU  - Bradley Lega
AU  - Barbara C. Jobst
AU  - Kathryn A. Davis
AU  - Cory Inman
AU  - Sameer A. Sheth
AU  - Paul A. Wanda
AU  - Youssef Ezzyat
AU  - Sandhitsu R. Das
AU  - Joel Stein
AU  - Richard Gorniak
AU  - Joshua Jacobs
TI  - Electrical Stimulation in Hippocampus and Entorhinal Cortex Impairs Spatial and Temporal Memory
AID  - 10.1523/JNEUROSCI.3049-17.2018
DP  - 2018 May 09
TA  - The Journal of Neuroscience
PG  - 4471--4481
VI  - 38
IP  - 19
4099  - http://www.jneurosci.org/content/38/19/4471.short
4100  - http://www.jneurosci.org/content/38/19/4471.full
SO  - J. Neurosci.2018 May 09; 38
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.