Subcortical correlates of “normal” and epileptiform EEG activities of the slow wave sleep state II in patients with intractable generalized seizures

Some muramyl peptides derived from bacterial peptidoglycan enhance slow-wave sleep (SWS). The purpose of this study was to test whether another cell wall component, lipopolysaccharide (LPS), and its lipid A moiety also have an effect on sleep. When injected intravenously, both LPS and lipid A enhanced the duration of SWS, increased electroencephalogram delta-wave amplitudes, suppressed rapid eye movement (REM) sleep, and induced biphasic fevers. The effects of intravenously administered lipid A and LPS on SWS were present primarily during the first 3 h postinjection. Intraventricular lipid A administration enhanced SWS, did not suppress REM, and induced a monophasic fever; the SWS effect had a 3-h latency, whereas temperature started to rise during the second hour. Regardless of the route of administration, within the dose range used here, sleep was normal by the following criteria: sleep was episodic, animals could be easily aroused, and brain temperature, although elevated to "febrile" levels, continued to fluctuate during sleep-state transitions indistinguishably from control conditions. We conclude that LPS and lipid A are capable of modulating sleep.

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Waking and ventilatory responses to laryngeal stimulation in sleeping dogs

Journal of Applied Physiology ◽

10.1152/jappl.1978.45.5.681 ◽

1978 ◽

Vol 45 (5) ◽

pp. 681-689 ◽

Cited By ~ 130

Author(s):

C. E. Sullivan ◽

E. Murphy ◽

L. F. Kozar ◽

E. A. Phillipson

Keyword(s):

Endotracheal Tube ◽

Eye Movement ◽

Slow Wave ◽

Rem Sleep ◽

Slow Wave Sleep ◽

Sleep State ◽

Ventilatory Responses ◽

Cardiac Responses ◽

Prolonged Apnea ◽

Sleep Arousal

We studied waking and ventilatory responses to laryngeal stimulation during sleep in three dogs. The dogs breathed through an endotracheal tube inserted caudally into the trachea through a tracheostomy. Laryngeal stimulation was produced either by inflating a small balloon that was positioned in the rostral tracheal segment, or by squirting water onto the larynx through a catheter inserted through the tracheostomy. Airflow was measured with a pneumotachograph, and sleep state was determined by behavioral, electroencephalographic, and electromyographic criteria. We found that the degree of laryngeal stimulation required to produce arousal and coughing was higher in rapid-eye-movement (REM) sleep than in slow-wave sleep (SWS). Stimuli that failed to cause arousal from SWS often produced a single expiratory effort, or brief apnea (1--2 s) and bradycardia. In contrast, during REM sleep subarousal stimuli often resulted in prolonged apnea (greater than 10 s) and marked bradycardia. We conclude that during REM sleep arousal responses to laryngeal stimulation are depressed, but ventilatory and cardiac responses are intact.

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Modal-Polar Representation of Evoked Response Potentials in Multiple Arousal States

Frontiers in Human Neuroscience ◽

10.3389/fnhum.2021.642479 ◽

2021 ◽

Vol 15 ◽

Author(s):

Rawan K. El-Zghir ◽

Natasha C. Gabay ◽

Peter A. Robinson

Keyword(s):

Transfer Function ◽

Slow Wave ◽

Slow Wave Sleep ◽

Brain Activity ◽

Evoked Response ◽

Temporal Part ◽

Sleep State ◽

Global Mode ◽

Eyes Closed ◽

Evoked Response Potentials

An expansion of the corticothalamic transfer function into eigenmodes and resonant poles is used to derive a simple formula for evoked response potentials (ERPs) in various states of arousal. The transfer function corresponds to the cortical response to an external stimulus, which encodes all the information and properties of the linear system. This approach links experimental observations of resonances and characteristic timescales in brain activity with physically based neural field theory (NFT). The present work greatly simplifies the formula of the analytical ERP, and separates its spatial part (eigenmodes) from the temporal part (poles). Within this framework, calculations involve contour integrations that yield an explicit expression for ERPs. The dominant global mode is considered explicitly in more detail to study how the ERP varies with time in this mode and to illustrate the method. For each arousal state in sleep and wake, the resonances of the system are determined and it is found that five poles are sufficient to study the main dynamics of the system in waking eyes-open and eyes-closed states. Similarly, it is shown that six poles suffice to reproduce ERPs in rapid-eye movement sleep, sleep state 1, and sleep state 2 states, whereas just four poles suffice to reproduce the dynamics in slow wave sleep. Thus, six poles are sufficient to preserve the main global ERP dynamics of the system for all states of arousal. These six poles correspond to the dominant resonances of the system at slow-wave, alpha, and beta frequencies. These results provide the basis for simplified analytic treatment of brain dynamics and link observations more closely to theory.

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