Independent dynamics of low, intermediate, and high frequency spectral intracranial EEG activities during human memory formation
Victoria S. Marks,
Krishnakant V. Saboo,
Çağdaş Topçu,
Michal Lech,
Theodore P. Thayib,
Petr Nejedly,
Vaclav Kremen,
Gregory A. Worrell,
Michal T. Kucewicz
Affiliations
Victoria S. Marks
Graduate School of Biomedical Sciences, Mayo Clinic, USA
Krishnakant V. Saboo
Department of Electrical and Computer Engineering, University of Illinois, Urbana-Champaign, IL, USA
Çağdaş Topçu
Multimedia Systems Department, Faculty of Electronics, Telecommunications and Informatics, BioTechMed Center, Gdansk University of Technology, Gdansk, Poland; Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland; Department of Neurology, Mayo Clinic, Rochester, MN, USA
Michal Lech
Multimedia Systems Department, Faculty of Electronics, Telecommunications and Informatics, BioTechMed Center, Gdansk University of Technology, Gdansk, Poland; Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland; Department of Neurology, Mayo Clinic, Rochester, MN, USA
Theodore P. Thayib
Department of Computer Engineering, Iowa State University, Ames, Iowa, USA
Petr Nejedly
Department of Neurology, Mayo Clinic, Rochester, MN, USA; The Czech Academy of Sciences, Institute of Scientific Instruments, Brno, Czech Republic
Vaclav Kremen
Department of Neurology, Mayo Clinic, Rochester, MN, USA; Robotics, and Cybernetics, Czech Institute of Informatics, Czech Technical University in Prague, Prague, Czech Republic
Gregory A. Worrell
Department of Neurology, Mayo Clinic, Rochester, MN, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic, USA
Michal T. Kucewicz
Multimedia Systems Department, Faculty of Electronics, Telecommunications and Informatics, BioTechMed Center, Gdansk University of Technology, Gdansk, Poland; Department of Neurology, Mayo Clinic, Rochester, MN, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic, USA; Corresponding author at: Multimedia Systems Department, Faculty of Electronics, Telecommunications and Informatics, BioTechMed Center, Gdansk University of Technology, Gdansk, Poland.
A wide spectrum of brain rhythms are engaged throughout the human cortex in cognitive functions. How the rhythms of various frequency ranges are coordinated across the space of the human cortex and time of memory processing is inconclusive. They can either be coordinated together across the frequency spectrum at the same cortical site and time or induced independently in particular bands. We used a large dataset of human intracranial electroencephalography (iEEG) to parse the spatiotemporal dynamics of spectral activities induced during formation of verbal memories. Encoding of words for subsequent free recall activated low frequency theta, intermediate frequency alpha and beta, and high frequency gamma power in a mosaic pattern of discrete cortical sites. A majority of the cortical sites recorded activity in only one of these frequencies, except for the visual cortex where spectral power was induced across multiple bands. Each frequency band showed characteristic dynamics of the induced power specific to cortical area and hemisphere. The power of the low, intermediate, and high frequency activities propagated in independent sequences across the visual, temporal and prefrontal cortical areas throughout subsequent phases of memory encoding. Our results provide a holistic, simplified model of the spectral activities engaged in the formation of human memory, suggesting an anatomically and temporally distributed mosaic of coordinated brain rhythms.
