Hong-Viet V Ngo1, Mitja Seibold2, Désirée C Boche2, Matthias Mölle3, Jan Born4. 1. School of Psychology, University of Birmingham, Birmingham B15 2TT, United Kingdom; Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen 72076, Germany. 2. Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen 72076, Germany. 3. Center of Brain, Behavior and Metabolism, University of Lübeck, Lübeck, Germany. 4. Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen 72076, Germany; Centre for Integrative Neuroscience, University of Tübingen, Tübingen 72076, Germany. Electronic address: jan.born@uni-tuebingen.de.
Abstract
BACKGROUND: The consolidation of sleep-dependent memories is mediated by an interplay of cortical slow oscillations (SOs) and thalamo-cortical sleep spindles. Whereas an enhancement of SOs with auditory closed-loop stimulation has been proven highly successful, the feasibility to induce and boost sleep spindles with auditory stimulation remains unknown thus far. NEW METHOD: Here we tested the possibility to enhance spindle activity during endogenous SOs and thereby to promote memory consolidation. Performing a sleep study in healthy humans, we applied an auditory Spindle stimulation and compared it with an Arrhythmic stimulation and a control condition comprising no stimulation (Sham). RESULTS: With Spindle stimulation we were not able to directly entrain endogenous spindle activity during SO up-states. Instead, both Spindle and Arrhythmic stimulation evoked a resonant SO response accompanied by an increase in spindle power phase-locked to the SO up-state. Assessment of overnight retention of declarative word-pairs revealed no difference between all conditions. COMPARISON WITH EXISTING METHODS: Our Spindle stimulation produced oscillatory evoked responses (i.e., increases in SOs and spindle activity during SO up-states) quite similar to those observed after the auditory closed-loop stimulation of SOs in previous studies, lacking however the beneficial effects on memory retention. CONCLUSION: Our findings put the endeavour for a selective enhancement of spindle activity via auditory pathways into perspective and reveal central questions with regard to the stimulation efficacy on both an electrophysiological and a neurobehavioral level.
BACKGROUND: The consolidation of sleep-dependent memories is mediated by an interplay of cortical slow oscillations (SOs) and thalamo-cortical sleep spindles. Whereas an enhancement of SOs with auditory closed-loop stimulation has been proven highly successful, the feasibility to induce and boost sleep spindles with auditory stimulation remains unknown thus far. NEW METHOD: Here we tested the possibility to enhance spindle activity during endogenous SOs and thereby to promote memory consolidation. Performing a sleep study in healthy humans, we applied an auditory Spindle stimulation and compared it with an Arrhythmic stimulation and a control condition comprising no stimulation (Sham). RESULTS: With Spindle stimulation we were not able to directly entrain endogenous spindle activity during SO up-states. Instead, both Spindle and Arrhythmic stimulation evoked a resonant SO response accompanied by an increase in spindle power phase-locked to the SO up-state. Assessment of overnight retention of declarative word-pairs revealed no difference between all conditions. COMPARISON WITH EXISTING METHODS: Our Spindle stimulation produced oscillatory evoked responses (i.e., increases in SOs and spindle activity during SO up-states) quite similar to those observed after the auditory closed-loop stimulation of SOs in previous studies, lacking however the beneficial effects on memory retention. CONCLUSION: Our findings put the endeavour for a selective enhancement of spindle activity via auditory pathways into perspective and reveal central questions with regard to the stimulation efficacy on both an electrophysiological and a neurobehavioral level.
Authors: J Karimi Abadchi; Mojtaba Nazari-Ahangarkolaee; Sandra Gattas; Edgar Bermudez-Contreras; Artur Luczak; Bruce L McNaughton; Majid H Mohajerani Journal: Elife Date: 2020-03-13 Impact factor: 8.713
Authors: Miguel Navarrete; Jules Schneider; Hong-Viet V Ngo; Mario Valderrama; Alexander J Casson; Penelope A Lewis Journal: Sleep Date: 2020-06-15 Impact factor: 5.849