Biological Rhythms, Sleep & Waking

Default mode network (DMN)

A circuit that is active during periods of unfocused thought. Consists of the medial prefrontal cortex, the medial parietal cortex, the lateral parietal cortex, and the lateral temporal cortex. Suppresses focused activity.

hypopnea

A reduction in airflow during sleep

Restless leg syndrome (RLS)

A sleep disorder in which a limb, usually a leg, moves at regular intervals during sleep. Characterized by atypical dopamine function.

Parasomnias

Abnormal behavior or physiology during sleep. Nightmares, night terrors, somnambulism (sleepwalking), restless leg syndrom, ambien-induced.

Dyssomnias

Abnormality in the amount, or quality or timing of sleep. Insomnia, Narcolepsy, hypersomnia

Glutamate

Activity of this neurotransmitter is high in the fontal lobes during both waking and REM sleep, and it is likely that it promotes REM-on processes.

Circadian (Rhythm)

Any rhythmic change that continues at close to a 24 hour cycle in the absence of external cues (e.g., light/dark). body temperature cortisol secretion sleep and wakefulness

Locus coeruleus

Area of the pons that participates in waking through its rich connections to the thalamus, hippocampus, and cortex. It is the source of most of the norepinephrine in the brain. It is most active when people are vigilant and alert, relatively less active when a person is relaxed, quieter during NREM sleep, and silent during REM.

Adenosine

Caffeine keeps us awake by blocking receptors for _____, an ATP byproduct that has an inhibitory effect on many brain systems. This purine neuromodulator accumulates until sleep occurs, specifically inhibiting neurons releasing waking neurochemicals (e.g. ACh, serotonin, and norepinephrine)

Actogram

Collects data in activity for rodents

Zolpidem (ambien)

Common medication prescribed for insomnia. GABA agonist.

ultradian cycles

Cycles that occur about every 90 to 120 minutes within the 24 hour day

Tau

Endogenous rhythm period called

histamine

Major neurochemical in some neurons in the thalamus and hypothalamus. These neurons project widely throughout the forebrain, and their activity is associated with alertness (low activity during NREM and REM sleep). Antagonists produce drowsiness. Non-drowsy versions of this drug avoids this side effect by not crossing the blood-brain barrier.

Hypocretin

Narcoleptic dogs have a mutant gene for _____ (aka Orexin) receptors. Promotes wakefulness (activates LC) and inhibits REM sleep.

Norepinephrine

Neurotransmitter from the locus coeruleus is highest during waking, drops off during NREM sleep, and is very low during REM sleep. Agonists delay sleepiness.

serotonin

Neurotransmitter from the raphe nuclei is highest during waking, drops off during NREM sleep, and is very low during REM sleep. People with major depressive disorder initiate REM too early and too frequently during the sleep cycle, possibly due to reduced _____ activity.

Acetylcholine

Neurotransmitter released by the pons and basal forebrain is associated with both waking and REM sleep. Agonists produce high level of mental alertness.

pontine reticular formation> lateral geniculate nucleus of the thalamus> occipital lobe

Pathway of PGO waveforms

pontine reticular formation> medulla> motor systems of the spinal cord

Pathway of inhibitory messages that cause the muscular paralysis accompanying REM.

Stage 1

Period of sleep in which some theta wave activity now occurs, and heart rate and muscle tension begin to decrease. Occasionally disturbed by myoclonia.

endogenous

Produced within the body

Onset insomnia

Sleep disorder in which the individual has difficulty getting to sleep at bedtime.

suprachiasmatic nucleus (SCN)

The body's internal master clock in the hypothalamus. Active only during the day, regardless of diurnal or nocturnal.

Zeitgeber ("time-giver")

The stimuli that an organism uses to synchronize with the environment is called a

Free running

Without zeitgeber, drift occurs, but still gets close to 24 hour period. Called

per, tim (period and timeless)

____ and ____ proteins inhibit the Clock protein, whereas the Clock protein pomotes the production of more ____ and ___ proteins.

Serotonin

____ levels typically drop in the fall and winter, and people vulnerable to seasonal depression might experience a greater than normal decrease.

nightmare

a REM dream with disturbing content

hypnogogic hallucinations

a REM-type dream that intrudes into the waking state prior to the onset of sleep.

hypnopompic hallucinations

a REM-type dream that intrudes into the waking state upon awakening.

Delta wave

a brain waveform having 1 to 4hz that occurs during stages 3 and 4 of NREM sleep

beta wave

a brain waveform having 14 to 30hz, associated with high levels of alertness during wakefulness.

theta wave

a brain waveform having 4 to 7hz found primarily in lighter stages of NREM sleep

alpha wave

a brain waveform having 8 to 13hz, associated with less alertness and more relaxation than high alertness waveforms.

gamma band activity

a brain waveform having more than 30 cycles per second , associated with the processing of sensory input.

K-complex

a brief burst of brain activity consisting of single delta waves, occurring during stage 2 NREM sleep.

Cataplexy

a feature of narcolepsy in which REM muscle paralysis intrudes into the waking state

sleep paralysis

a feature of narcolepsy in which REM muscle paralysis occurs preceding or following actual sleep.

cholinergic mesopontine nuclei

a group of cells located at the border of the pons and midbrain that use ACh as their major neurotransmitter and participate in the maintenance of waking.

cortisol

a hormone released by the adrenal glands that promotes arousal

growth hormone

a hormone released during stages 3 and 4 of slow-wave sleep that promotes growth, increases in bone and muscle mass, and immune system function.

Myoclonia

a muscle jerk occurring in early stages of sleep.

rapid eye movement sleep

a period of sleep characterized by desynchronous brain activity, muscle paralysis, eye movment, and storylike dream behavior.

non-REM sleep

a period of sleep characterized by, synchronous brain activity, reductions in heart rate, and muscle relaxation.

Sleep spindle

a short burst of 12 to 14hz waves observed during NREM sleep. Generated by interactions between the thalamus and the cortex.

Narcolepsy

a sleep disorder characterized by the intrusion of REM sleep, and occasionally REM paralysis, into the waking state. Results from disruptions in the synthesis of orexins (appetite; monitors internal/external states and adjusts level of arousal) Orexin-secreting cells in the hypothalamus are damaged.

REM Sleep behavior disorder

a sleep disorder in which the normal REM paralysis is absent. Can result from brain damage, particularly in the pons. Can be treated with benzodiazepines or melatonin.

Sudden infant death syndrome (SIDS)

a syndrome in which an otherwise healthy infant stops breathing and dies during sleep.

activation-synthesis theory

a theory suggesting that dream content reflects ongoing neural activity.

evolutionary model of dreaming

a theory suggesting that dreaming provides the advantage of consolidating memories during sleep rather than during waking.

threat simulation hypothesis

a theory suggesting that dreams provide practice for dealing with threats.

major depressive disorder with seasonal pattern

a type of depression that results from insufficient amounts of daylight during the winter months; formerly known as seasonal affective disorder.

sleep terror

an NREM episode in which the individual is partially aroused, disoriented, frightened, and inconsolable.

neural network model

an approach to understanding the function of dreaming as a means for forgetting irrelevant information.

PGO wave

an electrical waveform observed during REM sleep, originating in the pons and traveling to the thalamus and occipital lobe. Each wave is associated with an eye movement.

Clock

as levels of per and tim proteins increase, inhibition of the ____ protein ensures that no further per and tim proteins will be produced. The genes for this protein in humans appear to be implicated in schizophrenia and depression.

Retinohypothalamic pathway

axons of special cells that leave the optic nerve and project to the SCN, forming the _______.

intrinsically photosensitive retinal ganglion cells (ipRGCs)

axons of these special cells leave the optic nerve and project to the SCN, forming the retinohypothalamic pathway.

central sleep apnea

caused by deficits in the brain functions that maintain breathing during sleep, usually resulting from abnormalities in brainstem neurons.

obstructive sleep apnea hypopnea

caused by obstruction of the airways

Desynchronous

description of brain activity associated with independent action of many neurons and alertness.

Synchronous

descriptions of brain activity associated with neurons firing in unison and deep sleep

insomnia

difficulty initiating or maintaining enough sleep to feel rested.

melanopsin

ipRGCs do not process information about visual images. Instead they contain a photopigment known as ___.

orexin

neuropeptide that regulates arousal, wakefulness, and appetite

Stage 2

period of sleep which accounds for about 50% of the night's entire sleep. Further reductions in heart rate and muscle tension occur. The EEG begins to show sleep spindles and k-complexes.

melatonin

produced by pineal gland, a neurochemical that modulates brainstem structures related to waking and sleep.

preoptic area (POA) of the hypothalamus

receives input from the anterior raphe nuclei, forms inhibitory feedback loops with waking pathways. Electrical stimulation of the NREM-on cells produces immediate NREM sleep.

anterior raphe nuclei

serotonergic nuclei that communicate with the preoptic area and suprachiasmatic nucleus of the anterior hypothalamus as well as the cerebral cortex. Active during wakefulness, less active during NREM, and silent during REM.

Maintenance insomnia

sleep disorder in which the individual cannot stay asleep during the night.

sleep debt

the homeostatic control of sleep, in which sleep promotion is related to the preceding duration and intensity of wakefulness.

REM rebound

the increased amount of REM sleep following a period of REM deprivation.

Entrainment

the process of resetting the biological clock (or keeping it aligned). (ex: our endogenous clock is about 24.2 - 24.9 hours)

apnea

the total absence of airflow for a period of time during sleep.

Lucid dreaming

thoughtful dreaming; the dreamer is aware that he or she is dreaming and can manipulate the experience.