title: Hierarchical nesting of slow oscillations, spindles and ripples in the human hippocampus during sleep.
abstract: During systems-level consolidation, mnemonic representations initially reliant on the hippocampus are thought to migrate to neocortical sites for more permanent storage, with an eminent role of sleep for facilitating this information transfer. Mechanistically, consolidation processes have been hypothesized to rely on systematic interactions between the three cardinal neuronal oscillations characterizing non-rapid eye movement (NREM) sleep. Under global control of de- and hyperpolarizing slow oscillations (SOs), sleep spindles may cluster hippocampal ripples for a precisely timed transfer of local information to the neocortex. We used direct intracranial electroencephalogram recordings from human epilepsy patients during natural sleep to test the assumption that SOs, spindles and ripples are functionally coupled in the hippocampus. Employing cross-frequency phase-amplitude coupling analyses, we found that spindles were modulated by the up-state of SOs. Notably, spindles were found to in turn cluster ripples in their troughs, providing fine-tuned temporal frames for the hypothesized transfer of hippocampal memory traces.
authors.affiliation: School of Psychology, University of Birmingham, Birmingham, UK.|MRC Cognition and Brain Sciences Unit, Cambridge, UK.
authors.forename: Bernhard P
authors.initials: BP
authors.lastname: Staresina
authors.affiliation: Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, NL.|Institute of Psychology, Christian-Albrechts-University of Kiel, Kiel, Germany.
authors.forename: Til Ole
authors.initials: TO
authors.lastname: Bergmann
authors.affiliation: Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, NL.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Bonnefond
authors.affiliation: Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, NL.
authors.forename: Roemer
authors.initials: R
authors.lastname: van der Meij
authors.affiliation: Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, NL.
authors.forename: Ole
authors.initials: O
authors.lastname: Jensen
authors.affiliation: Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, NL.
authors.forename: Lorena
authors.initials: L
authors.lastname: Deuker
authors.affiliation: Department of Epileptology, University of Bonn, Bonn, Germany.
authors.forename: Christian E
authors.initials: CE
authors.lastname: Elger
authors.affiliation: German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.|Department of Neuropsychology, Institute of Cognitive Neuroscience, Ruhr University Bochum, Germany.
authors.forename: Nikolai
authors.initials: N
authors.lastname: Axmacher
authors.affiliation: Department of Epileptology, University of Bonn, Bonn, Germany.
authors.forename: Juergen
authors.initials: J
authors.lastname: Fell
mesh_terms: D000328:Adult; D004569:Electroencephalography / Q000379:methods; D004827:Epilepsy / Q000503:physiopathology; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D019579:Neocortex / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D055815:Young Adult