Clinical trial NCT04714879: Modulation of Memory Consolidation in Humans
Official title: Modulation of Memory Consolidation in Humans
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Sleep
Keywords: memory consolidation
Lead sponsor: University Medicine Greifswald
Sponsor class: OTHER
Collaborators: name: Technische Universität Berlin
First posted: 2021-01-19
Enrollment: 54
Sex: ALL
Minimum age (years): 50
Maximum age (years): 80
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Intervention model description: 7 experimental stimulation conditions (including sham stimulation) are tested in a randomized, counterbalanced, within-subject design
Primary purpose: OTHER

Brief summary: The goal of the present study is to optimize effects of slow oscillatory transcranial direct current stimulation (so-tDCS) on sleep physiology and memory consolidation in humans by combining computational and experimental human models in an iterative process. The investigator therefore works in cooperation with Prof. Dr. Klaus Obermayer (TU Berlin), who contributes computation models with the aim to mechanistically understand the impact of different perturbations on sleep-related electrophysiological features, and to subsequently optimize so-tDCS parameters for inducing SO and spindle activity.

Detailed description: Sleep plays an active role in long-term consolidation of memories. Specifically, slow oscillations (SO, large amplitude waves \<1 Hz) and sleep spindles (8-15 Hz), that can be measured by electroencephalography (EEG), appear to be critical for declarative memories. According to the "active system consolidation" account, newly encoded memories are reactivated during sleep, accompanied by sharp-wave ripple events (80-100 Hz) in the hippocampus, and redistributed to cortical long-term storage networks through a coordinated dialog between the hippocampus and neocortex. This dialog is supposedly mediated by a particular coupling between cortical SO and thalamo-cortical fast spindles (12-15 Hz), with spindles preferably occurring during SO up-phases, and hippocampal ripples grouped at the troughs of fast spindles. Slow spindles (8-12 Hz) are a separate kind of sleep spindle activity whose function in memory consolidation is less well understood.

Interventions targeting sleep parameters may not only make it possible to beneficially modulate a vital aspect of memory consolidation, i. e., sleep-dependent memory consolidation, but may also help to delineate which specific elements of the neural dynamics during sleep are crucial for successful consolidation.

Eligibility criteria: Inclusion Criteria:

* Adults aged between 50-80 years
* screened as healthy in a structured telephone interview

Exclusion Criteria:

* Mini Mental Status Examination scores below 24
* history of severe untreated medical, neurological, and psychiatric diseases
* sleep disorders
* alcohol or substance abuse
* brain pathologies identified on MRI scan
* intake of medication acting primarily on the central nervous system (e.g., antipsychotics, antidepressants, benzodiazepines, or any type of over-the-counter sleep-inducing drugs such as valerian),
* nonfluent German language abilities.

Primary outcomes:
measure: Changes in EEG power (μV²) of the slow oscillation frequency band (0.5-1 Hz) following so-tDCS during sleep
timeFrame: up to 20 weeks
measure: Changes in EEG power (μV²) of the sleep spindles frequency band (12-15 Hz) following so-tDCS during sleep
timeFrame: up to 20 weeks
measure: Changes in cross-frequency coupling (resultant vector length) between slow oscillations and sleep spindles following so-tDCS during sleep
timeFrame: up to 20 weeks
Secondary outcomes:
measure: Sleep architecture
timeFrame: up to 20 weeks
measure: Changes in EEG power (μV²) of the delta frequency band (1-4 Hz) following so-tDCS during sleep
timeFrame: up to 20 weeks
Other outcomes:
Locations:
city: Greifswald
country: Germany
facility: University medicine Greifswald
Study officials:
affiliation: University Medicine Greifswald
name: Agnes Floeel, Prof.
role: STUDY_DIRECTOR
References:
citation: Ladenbauer J, Khakimova L, Malinowski R, Obst D, Tonnies E, Antonenko D, Obermayer K, Hanna J, Floel A. Towards Optimization of Oscillatory Stimulation During Sleep. Neuromodulation. 2023 Dec;26(8):1592-1601. doi: 10.1016/j.neurom.2022.05.006. Epub 2022 Aug 16.