Effectiveness of Visual vs. Acoustic Closed-Loop Stimulation on EEG Power Density during NREM Sleep in Humans

Abstract

The aim of the study was to investigate whether visual stimuli have the same potency to increase electroencephalography (EEG) delta wave power density during non-rapid eye movement (NREM) sleep as do auditory stimuli that may be practical in the treatment of some sleep disturbances. Nine healthy subjects underwent two polysomnography sessions—adaptation and experimental—with EEG electrodes positioned at Fz–Cz. Individually adjusted auditory (pink noise) and visual (light-emitting diode (LED) red light) paired 50-ms signals were automatically presented via headphones/eye mask during NREM sleep, shortly (0.75–0.90 s) after the EEG wave descended below a preset amplitude threshold (closed-loop in-phase stimulation). The alternately repeated 30-s epochs with stimuli of a given modality (light, sound, or light and sound simultaneously) were preceded and followed by 30-s epochs without stimulation. The number of artifact-free 1.5-min cycles taken in the analysis was such that the cycles with stimuli of different modalities were matched by number of stimuli presented. Acoustic stimuli caused an increase (p < 0.01) of EEG power density in the frequency band 0.5–3.0 Hz (slow waves); the values reverted to baseline at post-stimuli epochs. Light stimuli did not influence EEG slow wave power density (p > 0.01) and did not add to the acoustic stimuli effects. Thus, dim red light presented in a closed-loop in-phase fashion did not influence EEG power density during nocturnal sleep.

Manipulations of sleep‐like slow‐wave activity by noninvasive brain stimulation

“…Although how exactly sleep influences memory is a matter of debate (Ellenbogen et al, 2006), consolidation of both declarative and procedural memory is a well‐established target of SWA (Born et al, 2006), and potentiation of memory in human subjects has been observed after transcranial application of electrical or magnetic oscillating potentials (Marshall et al, 2006) as well as after CLAS (see above) and occasionally closed loop visual, olfactory, and somatosensory stimulation (Bellesi et al, 2014; Choi et al, 2020; Danilenko et al, 2020; Riedner et al, 2011). To date, our recognition of the importance of sleep for performance in learning and memory tasks has relied on studies based on sleep deprivation/restriction (Alkadhi et al, 2013; Colavito et al, 2013), while noninvasive brain stimulation allows the investigation of memory function using detailed perturbation of sleep stages (Harrington & Cairney, 2021).…”

Lateralized tactile stimulation during NREM sleep globally increases both slow and fast frequency activities

“…Previous studies indicate that rhythmic vestibular stimulation may also increase slow frequency activity and deepen sleep during a daytime nap (Bayer et al, 2011 ). On the other hand, repetitive visual stimulation was not effective to enhance slow wave activity in contrast to acoustic stimulation of similar rhythmicity (Danilenko et al, 2020 ). The sleeping brain is particularly sensitive to information arising from the body (Wei & Van Someren, 2020 ), therefore, slow waves might be effectively elicited through the somatosensory pathway.…”

Real-Time Excitation of Slow Oscillations during Deep Sleep Using Acoustic Stimulation

“…The electroencephalography (EEG) is most used for its examination [ 3 ]. Four sleep stages are commonly detected according to the more recent guidelines published by the American Academy of Sleep Medicine (AASM) [ 4 ]: three non-rapid eye movement stages (NREM1, NREM2, and NREM3) and rapid eye movement (REM) sleep [ 5 , 6 ]. Deep sleep (NREM3) plays an important role in memory consolidation.…”