Study Objectives: Rapid eye movement (REM)-induced hypotonia of the major upper airway dilating muscle (genioglossus) potentially contributes to the worsening of obstructive sleep apnea that occurs during this stage. No prior human single motor unit (SMU) study of genioglossus has examined this possibility to our knowledge. We hypothesized that genioglossus SMUs would reduce their activity during stable breathing in both tonic and phasic REM compared to stage N2 sleep. Further, we hypothesized that hypopneas occurring in REM would be associated with coincident reductions in genioglossus SMU activity.
Design: The activity of genioglossus SMUs was studied in (1) neighboring epochs of stage N2, and tonic and phasic REM; and (2) during hypopneas occurring in REM.
Setting: Sleep laboratory.
Participants: 29 subjects (38 ± 13 y) (17 male).
Intervention: Natural sleep, including REM sleep and REM hypopneas.
Measurement And Results: Subjects slept overnight with genioglossus fine-wire intramuscular electrodes and full polysomnography. Forty-two SMUs firing during one or more of stage N2, tonic REM, or phasic REM were sorted. Twenty inspiratory phasic (IP), 17 inspiratory tonic (IT), and five expiratory tonic (ET) SMUs were characterized. Fewer units were active during phasic REM (23) compared to tonic REM (30) and stage N2 (33). During phasic REM sleep, genioglossus IP and IT SMUs discharged at slower rates and for shorter durations than during stage N2. For example, the SMU peak frequency during phasic REM 5.7 ± 6.6 Hz (mean ± standard deviation) was less than both tonic REM 12.3 ± 9.7 Hz and stage N2 16.1 ± 10.0 Hz (P < 0.001). The peak firing frequencies of IP/IT SMUs decreased from the last breath before to the first breath of a REM hypopnea (11.8 ± 10.9 Hz versus 5.7 ± 9.4 Hz; P = 0.001).
Conclusion: Genioglossus single motor unit activity is significantly reduced in REM sleep, particularly phasic REM. Single motor unit activity decreases abruptly at the onset of REM hypopneas.
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http://dx.doi.org/10.5665/sleep.3498 | DOI Listing |
J Neurosci
January 2025
Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI USA
Based on the activity of dopamine (DA) neurons during behavioral states, the DA system has long been thought to be foundational in regulating sleep-wake behavior; over the past decade advances in circuit manipulation and recording techniques have strengthened this perspective. Recently, several studies have demonstrated that DA release in regions of the limbic system is important in the promotion of REM sleep. Yet how DA dynamics change within bouts of sleep, how these changes are regulated, and whether they influence future state changes remains unclear.
View Article and Find Full Text PDFJ Sleep Res
December 2024
Radboud University Medical Centre, Donders Institute for Brain, Cognition and Behavior, Nijmegen, Netherlands.
Traditionally categorized as a uniform sleep phase, rapid eye movement sleep exhibits substantial heterogeneity with its phasic and tonic constituents showing marked differences regarding many characteristics. Here, we investigate how tonic and phasic states differ with respect to aperiodic neural activity, a marker of arousal and sleep. Rapid eye movement sleep heterogeneity was assessed using either binary phasic-tonic (n = 97) or continuous (in 60/97 participants) approach.
View Article and Find Full Text PDFMov Disord
December 2024
National Engineering Research Center of Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing, China.
Background: Abnormal rapid eye movement (REM) sleep, including REM sleep behavior disorder (RBD) and reduced REM sleep, is common in Parkinson's disease (PD), highlighting the importance of further study on REM sleep. However, the biomarkers of REM disturbances remain unknown, leading to the lack of REM-specific neuromodulation interventions.
Objective: This study aims to investigate the neurophysiological biomarkers of REM disturbance in parkinsonian patients.
Sleep Med
November 2024
Department of Psychiatry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong Special Administrative Region of China; Li Chiu Kong Family Sleep Assessment Unit, Department of Psychiatry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong Special Administrative Region of China; Li Ka Shing Institute of Health Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong. Electronic address:
Sleep
November 2024
Department of Neurology, Seoul National University Hospital, Seoul, Republic of Korea.
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