Glossary

Atonia: Lack of muscle tone or strength

Cataplexy: A symptom of narcolepsy in which a sudden loss of muscle tone is induced

Concordance Rate: A quantitative statistical measurement for the presence of a given genetic trait in both members of a pair of twins. (Dictionary.com)

Dorsal Pons: Located beneath the cerebellum in the brainstem, it is associated with acetylcholinergic activity.

Electroencephalogram (EEG): Measures normal and abnormal brain activity during the stages of sleep.

Electromyogram (EMG): Measures muscle atonia during REM sleep.

Electrooculogram (EOG): Measures normal and abnormal eye movement (horizontal and vertical) during different stages of sleep (specifically REM sleep).

Excessive Daytime Sleepiness/somnolence (EDS): A symptom of narcolepsy in which there is an overwhelming and recurring need to sleep at times when you want to be awake.

Gamma loop: The route followed by nerve impulses to induce a stretch reflex

Hypersomnolence: Excessive sleepiness

Hypnagogic Hallucinations: A symptom of narcolepsy in which there is vivid hallucinatory imagery at the onset of sleep.

Locus Coeruleus: A group of cell bodies in the pons involved in arousal and vigilance.

Monozygotic Twins: Genetically identical twins, which are derived from the same fertilized ovum or embryonic cell mass. (Dictionary.com)

Motoneurons: A neuron that connects functionally to a muscle fiber.

Multiple Sleep Latency Test (MSLT): A standardized procedure used to measure daytime sleepiness that involves a series of naps taken after a full nights rest.

Neuron: A cell of the nervous system that specializes in sending electrical signals.

Neuropeptide: Any of various natural or synthetic compounds found in brain tissue (like endorphins) containing two or more amino acids linked by the carboxyl group of one amino acid to the amino group of another. (Dictionary.com)

Polysomnogram: Multiple recordings of physiological parameters in order to assess sleep and wakefulness.  Usually includes an EEG, an EOG, and an EMG.

Proprioception: The mechanism involved in the self-regulation of posture and movement through stimuli originating in the receptors imbedded in the joints, tendons, muscles, and labyrinth.

Raphe Nuclei: A group of nuclei in the reticular formation of the medulla, pons, and midbrain and contains serotonergic neurons.

Receptor: A molecular structure or site on the surface or interior of a cell that binds with substances such as hormones, antigens, drugs, or neurotransmitters. (Dictionary.com)

REM sleep: The state of sleep during which rapid eye movements and dreaming occur.

Sleep Onset REM Periods (SOREMPs): Periods of REM (Rapid Eye Movement) sleep that occur during the MSLT (Multiple Sleep Latency Test) and are indicative of EDS (Excessive Daytime Somnolence/Sleepiness).

Sleep Paralysis: A symptom of narcolepsy in which there is an inability to talk or move for a brief period when falling asleep or waking up.

Tuberomammillary Nucleus: A nucleus (group of cell bodies) in the hypothalamus and is involved in cortical activation and behavioral arousal.