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locus coeruleus
a dark-colored group of noradreneric cell bodies located in the pons near the rostral end of the floor of the fourth ventricle; involved in arousal and vigilance
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REM sleep
A period of desynchronized EEG activity during sleep, at which thime dreaming, rapid eye movements and muscular paralysis occur; also called paradoxical sleep.
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cataplexy
A symptom of narcolepsy; complete paralysis that occurs during waking.
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electromyogram (EMG)
An electrical potential recorded from an electrode placed on or in a muscle.
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alpha activity
smooth electrical activity of 8-12 Hz recorded fron the brain; generally associated with a state of relaxation.
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zeitgeber
a stimulus (usually the light of dawn) that resets the biological clock that is responsible for circadian rhythms.
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adenosine
A chemical produced when increased neural activity requires the breakdown of glycogen stored in astrocytes; may increase delta activity during the next night's slepp and thus enable the region to recover from its energy expenditure
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theta activity
EEG activity of 3.5-7.5 Hz that occurs intermittently during early stages of slow wave sleep and REM sleep.
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fatal familial insomnia
A fatal inherited disorder characteized by progessive insomnia
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raphe nuclei
A group of nuclei located in the reticulat formation of the medulla,pons , and midbrain, situated along the midline; contain serotonergic neurons.
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drug dependency insomnia
an insomnia caused by the side effects of ever-increasing doses of sleeping medication
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rebound phenomenon
The increase frequency or intensity of a phenomenon after it has been temporarily suppressed; for example, the increase in REM sleep seen after a period of REM sleep deprivation.
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melatonin
A hormone secreted during the night by the pineal body; plays a role in circadian seasonal rhythms.
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sleep attack
a symptom of narcolepsy; an irresistible urge to sleep during the day, after which the person awakes feeling refreshed.
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medial pontine reticular formation (MPRF)
A region that contains neurons involved in the initiation of REM sleep; activated by acetylcholineric neurons of the peribrachial area.
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tuberomammillary nucleus
A nucleus in the ventral posterior hypothalamus, just rostral to the mammillary bodies; contains histaminergic neurons involved in cortical activation and behavioral arousal.
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sleep paralysis
a symptom of narcolepsy; paralysis occurring just before a person falls asleep.
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narcolepsy
A sleep disorder characterized by periods of irresistible sleep, attack of cataplexy, sleep paralysis, and hypnagogic hallucinations.
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ventrolateral preoptic area (VLPA)
a group of GABAergic neurons in the preoptic area whose activity suppresses alertness and behavioral arousal and promotes sleep.
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beta activity
Irregular electrical activity of 13-30 Hz recorded from the brain; generally associated with a state of arousal.
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suprachiasmatic nucleus (SCN)
a nucleus situated atop the optic chiasm. It contains a biological clock that is resposible for organizing many of the body's circadian rhythms
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REM sleep behavior disorder
A neurological disorder in which the person does not become paralyzed during REM sleep and thus acts out dreams
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hypocretin
a peptide, also known as orexin, produced by neurons whose cell bodies are located in the hypothalamus; their destruction causes narcolepsy
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basic rest-activity cycle
A 90-minute cycle (in humans) of waxing and waning alertness, controlled by a biological clock in the caudal brian stem; controls cycles of REM sleep and slow-wave sleep.
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hypnagogic hallucination
A symptom of narcolepsy; vivid dreams that occur just before a person falls asleep; accompanied by sleep paralysis.
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melanopsin
A photopigment present in ganglion cells in the retina whose axons transmit information to the SCN, the thalamus, and the olivary pretectal nuclei.
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sleep apnea
Cessation of breathing while slepping
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PGO wave
Bursts of phasic electrical activity originating in the pons, followed by activity in the lateral geniculate nucleus and visual cortex; a characteristic of REM sleep.
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Delta activity
Regular, synchronous electrical activity of less that 4 Hz recorded from the brain; occurs during the deepest stages of slow wave sleep.
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Pineal gland
a Gland attached to the dorsal tectum; produces melatonin and plays a role in circadian and seasonal rhythms
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slow-wave sleep
non-REM sleep, characterized by synchronized EEG activity during its deeper stages
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magnocellular nucleus
a nucleus in the medulla; involved in the muscular paralysis that accompanies REM sleep.
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non-REM sleep
All stages of sleep except REM sleep.
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electro-oculogram (EOG)
An electrical potential from the eyes, recorder by means of electrodes placed on the skin around them; detect eye movements.
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circadian rhythm
A daily rhthmical change in behaivor or physiological process.
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peribrachial area
region around the brachium conjunctivum, located in the dorsolateral pons; contains acetylchlinergic neurons involved in the initiation of REM sleep.
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