sleep and cortical states Flashcards by Victoria Beliveau

sleep definition

is a natural, reversible, recurrent state of reduced responsiveness to external stimulation that is accompanied by complex
and predictable changes in physiology

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sleep is characterized by

-Altered consciousness.
-Minimal motor & sensory activity.
-Specific pattern of brain activity.
-Reduced interactions with the external world.

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whats EEG

Electroencephalography(EEG) is an electrophysiological monitoring method to record electrical activity of the brain, with electrodes placed along the scalp

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EEG measures voltage currents resulting from electrical potentials (EPSP&IPESP) generated by _____ neurons, reflected in the EEG as electrical waves: ___ waves (_, __ , ___, ___ waves)

cortical
brain
α, β, θ, δ

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EEG is used to

Monitor sleep stages & diagnose sleep disorders (Polysomnography)
Diagnose neurological disorders (e.g.epilepsy, encephalopathies, stroke…)
-Monitor coma, brain death and anesthesia level

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characteristics of beta waves

highly alert, eyes open= low amplitude and high frequency

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characteristics of alpha waves

relaxed, eyes closed= low amplitude and high frequency

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characteristics of delta waves

deep sleep= high amplitude and low frequency

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characteristics of theta waves

drowsy= high amplitude and low frequency

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what are the 2 states of wakefulness

-active wakefulness: eyes open, active state
-resting wakefulness: eyes closed, relaxed state

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what are the 2 states of sleep

-non-rapid eye movement sleep (non-REM)
-rapid eye movement (REM) sleep

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EEG recording for wakefulness

Beta & Alpha waves: high EEG frequency (9–30 Hz) & low EEG amplitude

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EEG recording for Stage I

Theta waves: intermediate EEG frequency (5–8 Hz) & intermediate EEG amplitude (50 – 100 μV) and K-Complex (isolated slow wave)

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EEG recording for stage II

Theta waves and sleep spindle: high EEG frequency (11–15 Hz) & low EEG amplitude (50 μV).

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EEG recording for stage III &IV

slow waves (delta waves): low frequency (0.5 to 4 Hz) & high EEG amplitude (100 – 150 μV)

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EEG recording for REM sleep

Beta & Alpha waves: high EEG frequency (9–30 Hz) & low EEG amplitude (∼30 μV). The same as in Wakefulness.

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REM sleep (paradoxical sleep) frequency, amplitude, eyelids, m. tone, m. activity, predominance of what)

-High EEG frequency (10–30 Hz) & low EEG amplitude (∼30 μV), Beta & Alpha waves. The same as in wakefulness
-Rapid eye movements (REM): eyelids closed,
-Minimal muscle tone, muscle atonia (i.e. muscle paralysis),
-Transient muscle activity (i.e. jerky muscle activity),
-Predominance of dreams.

sleep occurs in what kinds of cycles

The period of each cycle is approximately 90 minutes (1h & 1⁄2) in human (i.e. 4 – 5 cycles/night).

what decreases in non-REM sleep throughout the night

Non-REM sleep is longer at the beginning of the sleep but as the sleeper becomes more rested through the night, the durations of non-REM decrease.

when is REM sleep the shortest

REM sleep is short at the beginning but becomes long at the end

During wakefulness the cerebral cortex and thalamus are kept excited by neurons of the _____ ______ System located at
the subcortical level

ascending arousal

what neurons of the ascending arousal syst are in the brainstem

Reticular Formation (Glutamate neurons)
Brainstem nuclei (Acetylcholine neurons)
Locus Coeruleus (Noradrenaline neurons)
Dorsal Raphe (Serotonin neurons)

what neurons of the ascending arousal syst are in the hypothalamus

Lateral Hypothalamus (Orexin neurons)
Posterior Hypothalamus (Histamine neurons)

what neurons of the ascending arousal syst are in the basal forebrain

Acetylcholine neurons Glutamate neurons

During wakefulness the cortex and thalamus are kept excited by

neurons of the Ascending Arousal System located at the subcortical level.

Cortical neurons discharge APs with ___ & _____ patterns (i.e. not at the same time), which results in a ___ amplitude and ____ frequency EEG activity: ‘_____ EEG’ activity (i.e. beta & alpha waves).

fast & irregular low fast desynchronized

The arousal system neurons stimulate also motor neurons in the spinal cord to keep a ____ muscle tone during wakefulness.

higher

during non-REM sleep, inhibitory neurons (mainly GABA) inhibit what to promote sleep

inhibit the neurons of the arousal sys

what is dreaming

Dreaming is the subjective experience of imaginary images, sounds/voices, thoughts or sensations during sleep, usually involuntarily (i.e. outside the control of the dreamer).

most of dreamings occur during what

REM sleep

do animals dream and what is their subjective experience

Dreaming occurs in animals as well. Animals certainly undergo REM sleep, but their subjective experience is difficult to determine

what 2 processes regulate sleep-wake cycle

process S (sleep homeostatic) and process C (circadian)

what is process S

(Sleep Homeostatic): sleep propensity (i.e. sleep need) accumulates across the day: -The more the person stays awake, the more the sleep propensity incerased. -The more the person stays asleep, the more the sleep propensity decerased.

what is process C

biological clock, under the control of the hypothalamus: -Follows the light-dark cycle. affect -Releases sleep-related hormones (e.g. Melatonin)

sleep is important for what

physical, cognitive and psychological well-being

what are the functions of sleep

-Resting of different parts of the body. -Restore natural balances among the neuronal centers. -Acceleration of neural maturation (need of sleep for youth). -Facilitation of learning and memory (neuronal plasticity). -Clearance of metabolic waste products generated by neural activity in the awake. -Conservation of metabolic energy. -Hormonal regulation. -etc.

what is insomnia

is a Non-REM Sleep deficiency characterized by a perceived inability to fall and remain asleep at night, although it may not represent a true inability to sleep (paradoxical insomnia = sleep state misperception)

what is hypersomnia

is a Wakefulness deficiency characterized by excessive daytime sleepiness. It is a failure in the activating of mechanisms that are necessary to maintain arousal during the day.

what is narcolepsy

is a REM sleep dysfunction seen in the form of sudden REM sleep onset from wakefulness (sleep attacks) and excessive daytime sleepiness. It is often associated with cataplexy (muscle paralysis) following a emotional reaction (e.g. fear, laugh). Caused by the loss of orixin neurons in the hypothalamus.

what is sleep walking (somnambulism)

is a Non-REM Sleep dysfunction characterized by a partial arousal (with low consciousness) from Non-REM sleep and performing activities that are usually performed during wakefulness (e.g. walking out of the room, eating, sex, driving, homicide...). A total amnesia of the event (i.e. do not recall the event).

what is REM sleep behaviour disorder (RBD)

is a REM sleep dysfunction characterized by excessive motor activity during REM sleep due to the loss of REM sleep atonia. Patients act out the contents of their dreams. RBD is often a precursor to neurodegenerative diseases (e.g., Parkinson’s, Lewy body dementia...)

what is REM sleep behaviour disorder (RBD)