Authors :
Presenting Author: Hunki Kwon, PhD – Johns Hopkins Medicine / Kennedy Krieger Institute
Dhinakaran Chinappen, PhD, MBA, MEng – Massachusetts General Hospital, Harvard Medical School, Kennedy Krieger Institute, Johns Hopkins University
Anirudh Wodeyar, PhD – Maastricht University
Skyler Goodman, BS – Massachusetts General Hospital / Harvard Medical School
Elizabeth Kinard, BS – Massachusetts General Hospital / Harvard Medical School
Kate Isaac, BS – Massachusetts General Hospital / Harvard Medical School
Catherine Chu, MD – Kennedy Krieger Institute / Johns Hopkins University School of Medicine
Mark Kramer, PhD – Boston University
Rationale:
We previously found that changes in frontal slow oscillations (SOs) and SO-spindle complexes rates by auditory stimulation positively predicted changes in sleep-dependent memory consolidation in controls and epilepsy. Additionally, stimulation delivered during SO upstates evoked SO and SO-spindle complexes maximally at FZ. Here, we test whether a novel closed loop auditory stimulation protocol designed to increase event rate increased sleep-dependent memory consolidation.
Methods:
Five healthy control subjects (mean 23.8 years, 2F) each completed two sessions (auditory stimulation or sham stimulation) consisting of motor sequence typing (MST) training, a 90-minute nap opportunity with high-density EEG recording, and post-nap MST testing. One session included auditory stimulation with 50 ms bursts of pink noise during stage N2 or N3 sleep, while the other session included no auditory stimulation (sham). Auditory stimulations were precisely timed to the peaks of delta waves with low spindle activity, using a real-time rhythm tracking method at FZ (Figure 1). During the MST task, subjects completed twelve 30-second trials per hand, separated by a 10-minute break, typing 5-digit sequences (e.g., 24132). Sleep-dependent memory consolidation was measured as the percent change between the last three pre- and first three post-sleep trials. SOs and sleep spindles were detected offline using validated detectors. SO-spindle complexes were defined as a spindle occurring within 1s after the negative peak of a SO. The percentages of stimulations that evoked SOs and SO-spindle complexes were calculated as the percentage of SOs occurring within +1s of auditory stimulation and spindles occurring within +1s of the negative peak of an evoked SO, respectively. To evaluate the impact of auditory stimulation on evoked event percentage (%), event rate (#/min), or sleep-dependent memory consolidation (%) and the relationship between event rate and sleep-dependent memory consolidation, we estimated linear mixed-effects models with age and sex as covariates and subject specific intercepts to account for multiple observations per subject.Results:
The modified closed loop stimulation paradigm evoked SOs (5.3% increase, p< 0.001) and SO-spindle complex