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Neuroimage. 2018 Sep;178:92-103. doi: 10.1016/j.neuroimage.2018.05.029. Epub 2018 May 19.

High-gamma activity in the human hippocampus and parahippocampus during inter-trial rest periods of a virtual navigation task.

Author information

1
ARC Centre of Excellence in Cognition and Its Disorders, Macquarie University, Sydney, NSW 2109, Australia; Department of Cognitive Science, Macquarie University, Sydney, NSW 2109, Australia. Electronic address: yi.pu@mq.edu.au.
2
Brain and Psychological Sciences Research Centre, Swinburne University of Technology, Melbourne, VIC 3122, Australia.
3
Program in Neurosciences and Mental Health, Hospital for Sick Children Research Institute, Toronto, Ontario M5G 0A4, Canada; Institute of Medical Sciences and Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 2J7, Canada; Department of Medical Imaging, University of Toronto, Toronto, Ontario M5T 1W7, Canada.
4
ARC Centre of Excellence in Cognition and Its Disorders, Macquarie University, Sydney, NSW 2109, Australia; Department of Cognitive Science, Macquarie University, Sydney, NSW 2109, Australia. Electronic address: blake.johnson@mq.edu.au.

Abstract

In rodents, hippocampal cell assemblies formed during learning of a navigation task are observed to re-emerge during resting (offline) periods, accompanied by high-frequency oscillations (HFOs). This phenomenon is believed to reflect mechanisms for strengthening newly-formed memory traces. Using magnetoencephalography recordings and a beamforming source location algorithm (synthetic aperture magnetometry), we investigated high-gamma (80-140 Hz) oscillations in the hippocampal region in 18 human participants during inter-trial rest periods in a virtual navigation task. We found right hippocampal gamma oscillations mirrored the pattern of theta power in the same region during navigation, varying as a function of environmental novelty. Gamma power during inter-trial rest periods was positively correlated with theta power during navigation in the first task set when the environment was new and predicted greater performance improvement in the subsequent task set two where the environment became familiar. These findings provide evidence for human hippocampal reactivation accompanied by high-gamma activities immediately after learning and establish a link between hippocampal high-gamma activities and subsequent memory performance.

KEYWORDS:

High-gamma oscillations; Hippocampus; Magnetoencephalography (MEG); Spontaneous reactivation; Virtual spatial navigation

[Indexed for MEDLINE]

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