Spontaneous Hemodynamic Oscillations during Human Sleep and Sleep Stage Transitions Characterized with Near-Infrared Spectroscopy

Abstract

Understanding the interaction between the nervous system and cerebral vasculature is fundamental to forming a complete picture of the neurophysiology of sleep and its role in maintaining physiological homeostasis. However, the intrinsic hemodynamics of slow-wave sleep (SWS) are still poorly known. We carried out 30 all-night sleep measurements with combined near-infrared spectroscopy (NIRS) and polysomnography to investigate spontaneous hemodynamic behavior in SWS compared to light (LS) and rapid-eye-movement sleep (REM). In particular, we concentrated on slow oscillations (3–150 mHz) in oxy- and deoxyhemoglobin concentrations, heart rate, arterial oxygen saturation, and the pulsation amplitude of the photoplethysmographic signal. We also analyzed the behavior of these variables during sleep stage transitions. The results indicate that slow spontaneous cortical and systemic hemodynamic activity is reduced in SWS compared to LS, REM, and wakefulness. This behavior may be explained by neuronal synchronization observed in electrophysiological studies of SWS and a reduction in autonomic nervous system activity. Also, sleep stage transitions are asymmetric, so that the SWS-to-LS and LS-to-REM transitions, which are associated with an increase in the complexity of cortical electrophysiological activity, are characterized by more dramatic hemodynamic changes than the opposite transitions. Thus, it appears that while the onset of SWS and termination of REM occur only as gradual processes over time, the termination of SWS and onset of REM may be triggered more abruptly by a particular physiological event or condition. The results suggest that scalp hemodynamic changes should be considered alongside cortical hemodynamic changes in NIRS sleep studies to assess the interaction between the autonomic and central nervous systems.

Brain Tissue Oxygen Saturation Increases During the Night in Adolescents

“…The mean change in tHb was 1.02 ± 6.81 µM (p=0.704, n=7), which was not significant. Individual data are shown 4 in Fig. 1.…”

“…While different studies investigated specific events during sleep, e.g. sleep apnoea [3], differences between sleep stages [4] or wakefulness and sleep [5] the temporal evolution of 2 the oxygen metabolism in the course of sleep is not clear. According to the synaptic homeostasis hypothesis [1], a popular hypothesis about the function of sleep, oxygen demand should be reduced during sleep and hence brain metabolism should be decreased.…”

A review on continuous wave functional near-infrared spectroscopy and imaging instrumentation and methodology

“…amplitude, frequency, phase) can be modulated by the stimulus/task to some degree. For example, it was shown that the amplitude of LF and VLF oscillations depend on the activity state (rest vs. task) (Obrig et al, 2000a), sleep stage (Näsi et al, 2011), body posture (Tachtsidis et al, 2003(Tachtsidis et al, , 2004, or age of the subject (Peng et al, 2008;Safonova et al, 2004). Thus, although these oscillations arise spontaneously, their stimulus/task-evoked modulation capability leads to the conclusion that they may also be part of the systemic activity type 1 and type 2 (SC2-3).…”

Intraoperative video-rate hemodynamic response assessment in human cortex using snapshot hyperspectral optical imaging

“…In brain hemodynamic imaging, the information is either provided topographically with the information effectively being averaged over the penetration depth of the light, 3,17,[19][20][21][22][23][24] or tomographically exploiting the penetration of visible and/or near-infrared light to provide volumetric information up to a few millimeters or centimeters underneath the surface. 14,[25][26][27][28] Most tomographic approaches are implemented through-skull and lead to diffused functional cortex maps, whereas topographic approaches are most often used for intraoperative applications during open-cranium surgery with brain tissue being imaged without the need to correct for light attenuation caused by intervening tissue including skin and skull.…”