Tonic REM Sleep Research Articles

Excitatory drive to the respiratory system in REM sleep.

REM sleep is sometimes divided into tonic and phasic stages. Tonic REM sleep processes are both excitatory and inhibitory to the respiratory system. Inhibitory effects arise from the atonic processes of the REM state and include atonia of thoracoabdominal and extrathoracic airway muscles. Excitatory effects include increases in respiratory rate, central respiratory drive and rate of rise of diaphragmatic activity. The combination of these varying antagonistic effects determines the level of ventilation.

Magnetic stimulation of the human brain during phasic and tonic REM sleep: recordings from distal and proximal muscles.

During REM sleep, a powerful postsynaptic inhibition of spinal motoneurons induces a generalized muscle hypotonia. Despite this inhibition, it has been shown that by transcranial magnetic stimulation of the brain (TMS), muscle responses of normal amplitude can be evoked in small hand muscles of humans. Tonic innervation during sleep is different in postural vs. limb muscles, and the spinal inhibition differs during tonic vs. phasic REM episodes, Both phenomena may affect muscle responses to TMS. In this study, muscle responses of 14 healthy subjects were compared to TMS in abductor digiti minimi, lumbar erector spinae, trapezius, and diaphragm during phasic and tonic REM sleep. In all four muscles, the amplitudes of the muscle responses were extremely variable, ranging for example in trapezius from -100% to +473% as compared to wakefulness. There was no systematic difference between the muscles. Moreover, no differences were found for TMS during phasic REM events compared to tonic REM sleep. Thus, responses to TMS during REM sleep may be preserved, with a decreased or increased amplitude. As a likely explanation, the cortical excitability and/or the spinal inhibition fluctuates during REM sleep in humans.

Major unipolar depression and mild Alzheimer's disease: differentiation by quantitative tonic REM EEG

In a previous report, tonic REM sleep epochs from the all-night sleep EEG were processed and analyzed to produce a diagnostic that discriminated mild Alzheimer's disease (AD) from cognitively unimpaired control subjects. Here, we examine the specificity of this diagnostic in distinguishing depression from AD. Twenty-four cognitively unimpaired seniors (aged 63±1.3) with major depressive disorder (unipolar) were monitored for all-night EEG in a manner identical to that used in our previous report. Tonic REM EEG epochs were preconditioned, spectrally analyzed and compated with known populations of control and AD EEG spectra. Instances when a given depressed subject's spectra fell within spectral zones unique to control or AD populations formed a diagnostic score (control, AD, neither of these). Diagnostic scores correctly identified 88% ( 21 24 ) of cognitively unimpaired seniors with major depressive disorder (unipolar). This can be compared with 89% ( 31 35 ) of mild AD subjects and 100% ( 43 43 ) of control subjects correctly identified in our previous report. This diagnostic also correctly classified as to eventual clinical AD/not AD outcome 8 subjects with both major depressive disorder and validated memory complaints. The diagnostic discrimination of AD is based on the fact that AD subjects have significantly less tonic REM eEG energy in the 13–30 Hz frequency range and more in the 1–10 Hz range than control or depressed subjects, as shown in conventional spectral analysis.

EEG markers of early Alzheimer's disease in computer selected tonic REM sleep

All night sleep/wake EEGs were examined for diagnostic sensitive to early Alzheimer's diesease (AD) using computer automated techniques. Thirty-nine AD patients and 43 normal controls underwent 9 h of EEG recording in the sleep laboratory. All-night EEGs were screened for ideal, low artifact tonic REM sleep using autoregressive and power spectral techniques. The frequency spectral during tonic REM sleep revealed a significant shift towards slower wave formeds in AD vs. control subjects. Beta (> 12 Hz0 was reduced adn theta and delta (2–8 Hz) increased in AD compared to control groups. This frequency shift was demonstrated by several analytic techniques, including binned spectral energies and unique zones in the frequency spectra. Discriminant analyses using optimal binned EEG variables correctly classified 74% of AD and 98% of control subjects, and unique zone scores correctly classified 92% of AD and 95% of control subjects, indicating that these sleep EEG changes are apparently predictive of AD status.

Quantitative analysis of the EEG during tonic REM sleep — methodology

Frequency and amplitude characteristics of the clinical (waking) electroencephalogram (EEG) can be diagnostically be limited by neuronal degenerative disorders such as Alzheimer's or other cortical dementias. However, interpretation of the clinical EEG may be limited by many factors, including movement and muscle artifacts and uncontrolled variations along the alert/drowsy continuum. Moreover, the clinical EEG involves subjective judgment by experts whose opinions often differ. In an effort to address these problems, we have developed a computer-automated technology that examines the digitized, all-night sleep EEG for frequency and amplitude characteristics of potential diagnostic relevance to Alzheimer's dementia. Robust time series analysis techniques and a modified power spectral analysis (Z-spectra) are used to suppress artifactual information and to automatically select samples of tonic REM sleep EEG. The spectra (amplitude vs. frequency relationship) of this specific EEG state is then assessed for diagnostically relevant information.

State-related incidence of spontaneous breathing during high frequency ventilation

Previous reports indicate that apnea is induced by high frequency ventilation (HFV) in anesthetized animals. We have studied consious dogs ventilated with HFV during sleep and wakefulness to determine if this apnea is state related. Eucapnic apnea or very low breathing frequencies were observed during quiet wakkfulness, quiet sleep and tonic REM sleep. However, spontaneous breathing at nearly normal rates was invariably seen during phasic REM sleep. We conclude that HFV as administered induces apnea or near apnea in conscious animals and that the inhibitory pathways causing this apnea are probably disabled during phasic REM sleep.

Developmental aspects of hippocampal electrical activity and motor behavior in the rat

The developmental aspects of hippocampal electrical activity and motor behavior were studied in freely moving infant rats implanted with microelectrodes in the CA1 and dentate regions. The pup's motor abilities developed concomitantly with hippocampal electroencephalographic (EEG) activity. The uncoordinated and limited locomotion of 6- to 9-day-old pups was associated with very low-amplitude, low-frequency, irregular activity, similar to that accompanying immobility. Starting at 10 days, the EEG-behavior correlation described by Vanderwolf and his colleagues became evident: Voluntary movements were associated with hippocampal theta rhythm whereas immobility was associated with irregular activity. A second, lower-frequency type of theta, not correlated with movement, also appeared at 10 days. It was induced by anticholnesterase drugs and abolished by anticholinergics. Administration of anticholinergics caused minor disruption of movement-related theta, especially in younger animals. Observations of tonic and phasic REM sleep also demonstrated that the two types of theta activity appeared at 10 days of age. Despite the difference in the time course of morphogenesis, the prenatally formed CA1 pyramidal region and the postnatally formed dentate granule region developed in parallel with respect to the appearance of both types of theta activity at about 10 days. Theta frequency and amplitude developed to adult values during the next 2 weeks, but the activity in CA1 remained smaller than in the dentate region. The study thus supported the hypothesis that there are two main generators of theta activity, the CA1 pyramidal region and the dentate region.