Stimulating forebrain communications: Slow sinusoidal electric fields over frontal cortices dynamically modulate hippocampal activity and cortico-hippocampal interplay during slow-wave states.
Author: Greenberg A1, Whitten TA1, Dickson CT2.
Affiliation:
1Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada, T6G 2E1. 2Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada, T6G 2E1; Department of Psychology, University of Alberta, Edmonton, AB, Canada, T6G 2H7; Department of Physiology, University of Alberta, Edmonton, AB, Canada, T6G 2E9. Electronic address: clayton.dickson@ualberta.ca.
Conference/Journal: Neuroimage.
Date published: 2016 Mar 3
Other:
Pages: S1053-8119(16)00186-5 , Special Notes: doi: 10.1016/j.neuroimage.2016.02.070. [Epub ahead of print] , Word Count: 253
Slow-wave states are characterized by the most global physiological phenomenon in the mammalian brain, the large amplitude slow oscillation (SO; ~ 1 Hz) composed of alternating states of activity (ON/UP states) and silence (OFF/DOWN states) at the network and single cell levels. The SO is cortically generated and appears as a travelling wave that can propagate across the cortical surface and can invade the hippocampus. This cortical rhythm is thought to be imperative for sleep-dependent memory consolidation, potentially through increased interactions with the hippocampus. The SO is correlated with learning and its presumed enhancement via slow rhythmic electrical field stimulation improves subsequent mnemonic performance. However, the mechanism by which such field stimulation influences the dynamics of ongoing cortico-hippocampal communication is unknown. Here we show - using multi-site recordings in urethane-anesthetized rats - that sinusoidal electrical field stimulation applied to the frontal region of the cerebral cortex creates a platform for improved cortico-hippocampal communication. Moderate intensity field stimulation entrained hippocampal slow activity (likely by way of the temporoammonic pathway) and also increased sharp-wave ripples, the signature memory replay events of the hippocampus, and further increased cortical spindles. Following cessation of high-intensity stimulation, SO interactions in the cortical-to-hippocampal direction were reduced while the reversed hippocampal-to-cortical communication at both SO and gamma bandwidths was enhanced. Taken together, these findings suggest that cortical field stimulation may function to boost memory consolidation by strengthening cortico-hippocampal and hippocampo-cortical interplay at multiple nested frequencies in an intensity-dependent fashion.
Copyright © 2016. Published by Elsevier Inc.
PMID: 26947518 [PubMed - as supplied by publisher]
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