Social partnering alters sleep in fear-conditioned Wistar rats.

Social support, when provided following a traumatic experience, is associated with a lower incidence of stress-related psychiatric disorders. Our hypothesis was that providing a social interaction period with a naive conspecific would improve sleep architecture in response to cued fear conditioning in Wistar rats. Rats were randomly assigned to either the socially isolated or socially partnered groups.

Modulation of the ultradian human nasal cycle by sleep stage and body position.

Objective:: The nasal cycle, which is present in a significant number of people, is an ultradian side-to-side rhythm of nasal engorgement associated with cyclic autonomic activity. We studied the nasal cycle during REM/non-REM sleep stages and examined the potentially confounding influence of body position on lateralized nasal airflow.

Methods:: Left- and right-side nasal airflow was measured in six subjects during an eight-hour sleep period using nasal thermistors.

Time- and behavioral state-dependent changes in posterior hypothalamic GABAA receptors contribute to the regulation of sleep.

Sleep-wake behavior is regulated by a circadian rhythm, homeostatically and by additional mechanisms that determine the timing of slow-wave sleep and rapid eye movement sleep (REMS) episodes. The posterior hypothalamus coordinates the neural and humoral signals with the rest-activity cycle. It contains wake-active neurons, and is a site where stimulation of inhibitory GABAA receptors promotes sleep, whereas their antagonism enhances wakefulness.

The α1 adrenoceptor antagonist prazosin enhances sleep continuity in fear-conditioned Wistar-Kyoto rats.

Fragmentation of rapid eye movement sleep (REMS) is well described in individuals with posttraumatic stress disorder (PTSD) and likely has significant functional consequences. Fear-conditioned rodents may offer an attractive model of the changes in sleep that characterize PTSD. Following fear conditioning (FC), Wistar-Kyoto (WKY) rats, a strain known to be particularly stress-sensitive, have increased REMS fragmentation that can be quantified as a shift in the distribution of REMS episodes towards the more frequent occurrence of sequential REMS (inter-REMS episode interval≤3 min) vs.

Coming to grips with a "new" state of consciousness: the study of rapid-eye-movement sleep in the 1960s.

The recognition of rapid-eye-movement sleep (REM) and its association with dreaming in 1953 by Aserinsky and Kleitman opened a new world to explore in the brain. Discussions at two major symposia in the early 1960s reveal that a state with characteristics resembling both wakefulness and sleep was overturning accepted views of the regulation of the two states. Participants grappled with the idea that cortical activation could occur during sleep.

Reduced γ range activity at REM sleep onset and termination in fear-conditioned Wistar-Kyoto rats.

Recent investigations of rapid eye movement sleep (REMS) continuity have emphasized the importance of transitions both into and out of REMS. We have previously reported that, compared to Wistar rats (WIS), Wistar-Kyoto rats (WKY) responded to fear conditioning (FC) with more fragmented REMS. Gamma oscillations in the electroencephalogram (EEG) are synchronized throughout the brain in periods of focused attention, and such synchronization of cell assemblies in the brain may represent a temporal binding mechanism.

Fear conditioning fragments REM sleep in stress-sensitive Wistar-Kyoto, but not Wistar, rats.

Pavlovian conditioning is commonly used to investigate the mechanisms of fear learning. Because the Wistar-Kyoto (WKY) rat strain is particularly stress-sensitive, we investigated the effects of a psychological stressor on sleep in WKY compared to Wistar (WIS) rats. Male WKY and WIS rats were either fear-conditioned to tone cues or received electric foot shocks alone.

Long-term effect of cued fear conditioning on REM sleep microarchitecture in rats.

Study Objectives: To study long-term effects of conditioned fear on REM sleep (REMS) parameters in albino rats.

Design: We have investigated disturbances in sleep architecture, including muscle twitch density as REMS phasic activity, and freezing behavior in wakefulness, upon reexposure to a conditioned stimulus (CS) on Day 1 and Day 14 postconditioning.

Subjects: Male Sprague-Dawley rats prepared for polysomnographic recordings.

Stress-induced changes in sleep in rodents: models and mechanisms.

Psychological stressors have a prominent effect on sleep in general, and rapid eye movement (REM) sleep in particular. Disruptions in sleep are a prominent feature, and potentially even the hallmark, of posttraumatic stress disorder (PTSD) (Ross, R.J.

Hypoglycemia activates arousal-related neurons and increases wake time in adult rats.

Hypoglycemia resulting from excess of exogenous or endogenous insulin elicits central nervous system activation that contributes to counterregulatory hormone secretion. In adult humans without diabetes, hypoglycemia occurring during sleep usually produces cortical activation with awakening. However, in adult humans with type 1 diabetes, hypoglycemic arousal appears blunted or absent.

Corticotropin-releasing factor microinjection into the central nucleus of the amygdala alters REM sleep.

Psychological stressors have a prominent effect on rapid eye movement sleep (REMS) in humans and animals. We hypothesized that the stress-related neurochemical corticotropin-releasing factor (CRF), acting in the amygdala, could initiate neural events that lead to REMS alterations. Therefore, we made bilateral microinjections of three different doses of CRF into the central nucleus of the amygdala (CeA) in five rats.

Sleep-related neurons in the central nucleus of the amygdala of rats and their modulation by the dorsal raphe nucleus.

The amygdala (AMY) plays an important role in initiating appropriate neurobehavioral responses to emotionally arousing events. Its major efferents from the central nucleus (Ace) to the basal forebrain, hypothalamus and brainstem permit it to influence sleep mechanisms. To characterize further the neuronal activity of AMY during sleep and wakefulness, we recorded single neuronal activity in Ace across behavioral states in freely moving, normally behaving rats.

Differential effect of sleep-wake states on lingual and dorsal neck muscle activity in rats.

Postural tone is reduced during slow-wave sleep (SWS) and absent during rapid eye movement sleep (REMS). In obstructive sleep apnea subjects, upper airway dilating muscles, including those of the tongue, show a similar pattern; this contributes to sleep-related airway obstructions. However, in healthy subjects, state-dependent changes in the activity of pharyngeal muscles are variable.

Tetrodotoxin inactivation of pontine regions: influence on sleep-wake states.

Studies using various methodologies have implicated n. reticularis pontis oralis (RPO) and n. subcoeruleus (SubC) in the generation of rapid eye movement sleep (REM).

REM sleep: a sensitive index of fear conditioning in rats.

To examine the influence of conditioned fear stimuli on sleep-wake states, we recorded sleep in Sprague-Dawley rats after exposure to tones previously paired with footshock. After habituation to a recording chamber and the recording procedure, a baseline sleep recording was obtained the next day. One day later, experimental animals were exposed to shock training designed to induce conditioned fear (FC), consisting of five tone-footshock pairings.

A rodent model of sleep disturbances in posttraumatic stress disorder: the role of context after fear conditioning.

Background: A prominent sleep disturbance, likely including a disruption of rapid eye movement sleep (REMS) continuity, characterizes posttraumatic stress disorder (PTSD). We set out to develop a fear conditioning paradigm in rats that displays alterations in sleep architecture analogous to those in PTSD.

Methods: Baseline polysomnographic recordings of rats were performed in a neutral context to which the rats had been habituated for several days.

Diagnosis of rapid eye movement sleep disorder with electroencephalography and treatment with tricyclic antidepressants in a dog.

A 9-month-old, female Labrador retriever mix was presented for two types of seizure-like episodes, one of which occurred only during sleep. The two types of episodes were morphologically distinct. An electroencephalogram (EEG) demonstrated that the sleep-associated episodes occurred during rapid eye movement (REM) sleep, supporting a diagnosis of a REM behavior disorder.

A serotonergic (5-HT2) receptor mechanism in the laterodorsal tegmental nucleus participates in regulating the pattern of rapid-eye-movement sleep occurrence in the rat.

Serotonin [5-hydroxytryptamine (5-HT)] plays an inhibitory role in rapid-eye-movement (REM) sleep although the exact mechanism(s) and site(s) of action are not known. It is commonly assumed that 5-HT exerts its influence on REM sleep via input from the dorsal raphe nucleus (DRN) directly onto cholinergic neurons involved in the generation of REM sleep. 5-HT(2) receptor sites have been found on cholinergic neurons in the laterodorsal tegmental nucleus (LDT) and pedunculopontine tegmental nucleus (PPT).

GABAergic regulation of REM sleep in reticularis pontis oralis and caudalis in rats.

The nucleus reticularis pontis oralis (RPO) and nucleus reticularis pontis caudalis (RPC) are implicated in the generation of rapid eye movement sleep (REM). Work in cats has indicated that GABA in RPO plays a role in the regulation of REM. We assessed REM after local microinjections into RPO and RPC of the gamma-aminobutyric acid-A (GABA(A)) agonist, muscimol (MUS), and the GABA(A) antagonist, bicuculline (BIC).

Influence of shock training and explicit fear-conditioned cues on sleep architecture in mice: strain comparison.

Fear conditioning is thought to model anticipatory anxiety. Inbred mouse strains exhibit different levels of reactivity to aversive environmental stimuli, which may reflect anxiety. We examined the effects of fear conditioning on sleep in mouse strains that differ on behavioral measures of anxiety.

Perverting medical history in the service of "animal rights".

Scientists frequently disagree on the interpretation of data. Such disagreements follow an informal set of rules, where one assumes that the contestants are honestly engaged even though biases may cloud their minds. A new group of individuals with medical training operates under a different set of rules, however: any statement or argument may be used to support the animal rightists' contention that using animals to advance human medicine is wrong.

The central nucleus of the amygdala and the wake-promoting effects of modafinil.

Modafinil, a novel non-amphetamine stimulant recently approved for the treatment of narcolepsy, has been shown to increase waking in both animals and humans. However, its mechanism of action is currently unknown. Earlier research into the brain structures responsible for the wake-producing actions of modafinil implicated the central nucleus of the amygdala (ACe) as a possible site of action [Neuroscience 87 (1998) 905-911; Neurosci.