Theta power and theta-gamma coupling support long-term spatial memory retrieval

Author: Umesh Vivekananda1, Daniel Bush1,2, James A Bisby1,2, Sallie Baxendale1, Roman Rodionov1, Beate Diehl1, Fahmida A Chowdhury1, Andrew W McEvoy1, Anna Miserocchi1, Matthew C Walker1, Neil Burgess1,2,3
Affiliation: <sup>1</sup> Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK. <sup>2</sup> UCL Institute of Cognitive Neuroscience, London, UK. <sup>3</sup> Wellcome Centre for Human NeuroImaging, University College London, London, UK.
Conference/Journal: Hippocampus
Date published: 2020 Dec 2
Other: Special Notes: doi: 10.1002/hipo.23284. , Word Count: 156

Hippocampal theta oscillations have been implicated in spatial memory function in both rodents and humans. What is less clear is how hippocampal theta interacts with higher frequency oscillations to support long-term memory. Here we asked 10 presurgical epilepsy patients undergoing intracranial EEG recording to perform a long-term spatial memory task in desktop virtual reality and found that increased theta power in two discrete bands ("low" 2-5 Hz and "high" 6-11 Hz) during cued retrieval was associated with improved task performance. Similarly, increased coupling between "low" theta phase and gamma amplitude during the same period was associated with improved task performance. Finally, low and high gamma amplitude appeared to peak at different phases of the theta cycle; providing a novel connection between human hippocampal function and rodent data. These results help to elucidate the role of theta oscillations and theta-gamma phase-amplitude coupling in human long-term memory.

Keywords: gamma; hippocampus; phase amplitude coupling; spatial memory; theta.

PMID: 33263940 DOI: 10.1002/hipo.23284