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84 Cards in this Set
- Front
- Back
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How is sleep distinguished from quiet wakefulness?
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a decreased ability to react to external stimuli.
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What problems has sleep deprivation been linked to?
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Sleep deprivation has been linked to many health problems including obesity, high blood pressure, mood related disorders, depression, decreased productivity, and safety issues in the home, on the job, and on the road.
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free-running: defn
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in the absence of cues (light/dark cycles). sleep wake cycles lengthens and shows a phase-advance
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T/F To synchronize or photo-entrain physiological processes with the day-night cycle, the biological clock must be able to detect light differences in the day-night cycle
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T
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How are differences in the day-night cycle detected?
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Such detection is accomplished by the melanopsin containing RGCS which act as irradiance detectors.
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What happens to melanopsin-containing cells in light?
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Melanopsin photopigment leads to a depolarization by light
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The mammalian circadian rhythm is directly controlled by the ___of the hypothalamus
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SCN - suprachiasmatic n
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T/F The circadian rhythm must be reset daily to be synchronized with changing levels of light and darkness and allow animals to adapt to changing levels of light throughout the day and even the year. This requires constant entrainment of SCN with light- the most powerful entrainment cue.
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T
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intrinsically photosensitive Retinal Ganglion Cells (ipRGC): what is it?
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unlike other retinal ganglion cells, intrinsically photosensitive. This means that they are a third class of retinal photoreceptors, excited by light even when all influences from classical photoreceptors are blocked.
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The primary pathway responsible for pupillary reflex in response to light.
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ipRGCs.
The OPN (optic pretectal nucleus) controls pupillary light reflex by receiving bilateral sensory input from ipRGC axons; output from OPN reaches the Edinger-Westphal nucleus of the midbrain which synapses with pupillary sphincter muscle and ciliary muscle of the eye. These muscles then directly control opening and closing of the pupil in response to different levels of light exposure. |
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ipRGCs form the _____ tract
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retinohypothalamic
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ipRGCs project to _____
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SCN of hypothalamus
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SCN through its projection to other hypothalamic nuclei governs:
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sleep wake cycle
body temperature hormone secretion (melatonin, cortisol, vasopressin) blood pressure urine production |
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What EEG waves described by:
Awake, alert, active processing of information 14-60 Hz, <1mV. |
Beta
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What EEG waves described by:
quiet wakefulness, eye closed, relaxation/meditation 8-13 Hz 10-50mV |
Alpha waves
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What EEG waves described by:
early stages of sleep 4-7 Hz 50-100 mV. |
Theta waves
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What EEG waves described by:
deep sleep, 0.5 to 3 Hz 100-200mV |
Delta waves
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brain death looks like what on EEG?
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Flat
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Compared to Beta waves, Delta waves have _____ amplitude and _______ frequency.
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Higher; Lower
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Sleep architecture follows a pattern of alternating non-REM and REM (rapid eye movement) sleep throughout a typical night in a cycle that repeats itself about every __ minutes.
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90
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non-REM sleep is characterized by an EEG in which the waves have a _ amplitude and a __ frequency.
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greater; lower
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What sleep stage:
* Between being awake and falling asleep * Light sleep |
Stage 1
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What sleep stage:
* Onset of sleep * Becoming disengaged from surroundings * Breathing and heart rate are regular * Body temperature drops |
Stage 2
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What are sleep spindles?
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Sleep spindles in EEG reflect thalamocortical oscillations
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During what stage of sleep do you see sleep spindles?
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Stage 2
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What are K complexes?
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reflect outward flow of dendritic current from layers II/III of cortex, synchronous reduction of cortical activity leads to membrane hyperpolarization or down states which aid in the generation of thalamocortical oscillations and sleep spindles.
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During what stage of sleep do you see K complexes?
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Stage 2
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What sleep stage:
known as slow-wave sleep because of the prevalence of delta waves |
Stage 4
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What sleep stage:
* Deepest and most restorative stages of sleep * Blood pressure drops * Breathing becomes slower * Muscles are relaxed * Blood supply to muscles increases * Tissue growth and repair occurs * Energy is restored * Hormones are released |
Stages 3 and 4
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Characteristics of REM
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First occurs about 90 minutes after falling asleep and recurs (4 times) about every 90 minutes, getting longer later in the night
EEG resembles the waking state Increase in blood pressure, heart rate and respiration Rapid ballistic eye movement Pupillary constriction Diminished response to somatic stimulu Paralysis of large muscle groups Spontaneous penile erection Dreaming |
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What are PGO (Ponto-geniculo-occipital) waves?
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Phasic field potentials recorded in pons, LGN, occipital cortex
that precedes REM sleep |
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Circuitry involved in decreased sensation and muscle paralysis during REM sleep?
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-Inhibition of Lower motor neurons --> paralysis
-Inhibition of cells in dorsal column nuclei --> Diminished response to somatic sensory stimuli |
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What is a hypnogram?
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A hypnogram is a minute-by-minute graphic record of a night’s sleep, as captured by an EEG. The hypnogram the sequence in which the various stages of sleep occur and the times at which each stage starts and ends.
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During progressive sleep cycles, time of REM gets _______ while Stage 4 sleep gets _______
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Longer; Shorter
Stage 4 sleep lasts longest in the first cycle; REM sleep lasts longest in the last (about 4th) cycle |
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How does sleep and sleep needs change with age?
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Adults require 7-8 hrs
Infants require up to 17 hrs With age, episodes are shorter and sleep is lighter Total amount of sleep decreases with age REM decreases with age SWS decreases with age |
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REM and Slow-Wave sleep _______ with age
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decrease
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What brainstem nuclei are active during wakefulness?
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All: Raphe, Locus Coreuleus, Tuberomammillary, Cholinergic
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What brainstem nuclei are active during non-REM sleep?
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All of their activity is decreased
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What brainstem nuclei are active during REM sleep?
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Cholinergic (PGO waves)
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What is the reticular activating system?
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Reticular activating system is a group of cholinergic nuclei at pons midbrain junction that has widespread projections throughout thalamus and cortex
Active during waking state and REM Activation leads to EEG desychronization |
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What brainstem nuclei are responsible for turning REM sleep off?
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Locus coeruleus - NE
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What regulates Activity of brainstem neurons?
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Activity of brainstem neurons are modulated by hypothalamic nuclei
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What affect does the ventrolateral preoptic (VLPO)
nucleus of hypothalamus have on sleep? |
VLPO inhibits (GABA) Tuberomammillary n and brainstem nuclei and promotes sleep
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What affect does the tuberomammilly nuclei (TMN) have on sleep?
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TMN neurons utilize histamine and when active promotes wakefulness
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What effect does the lateral hypothalamus (LH) have on sleep?
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LH neurons synthesize the peptide orexin (hypocretin), which promotes wakefulness
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What is orexin/hypocretin?
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Protein the promotes wakefulness. Defective in narcolepsy.
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Wakefulness-promoting nuclei:
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orexinergic lateral hypothalamic area,
histaminergic tuberomammillary nucleus cholinergic pedunculopontine, tegmental nucleus noradrenergic locus coeruleus sertoninergic serotinergic raphe nuclei. |
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Sleep-promoting nuclei:
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GABAergic ventrolateral preoptic nucleus of hypothalamus.
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How do benzos promote sleep?
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Benzodiazepines enhance the effect of the GABA, and results in sedative, hypnotic (sleep inducing), anti-anxiety, anticonvulsant, muscle relaxant. New compounds which are structurally similar (benzo-like) such as Ambien (Zolpidem), Sonata (Zaleplon), Lunesta (Eszopiclone), are a prescription meds used for the short-term treatment of insomnia They are short-acting hypnotics that potentiate GABA, by binding to GABAA receptors at the same location as benzodiazepines.It works quickly (usually within 15 minutes) and has a short half-life
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How does caffeine promote wakefulness?
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adenosine receptor antagonist
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How does Modafinil promote wakefulness?
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Modafinil increase the release of monoamines, and elevates histamine and is now the drug of choice to treat daytime sleepiness brought about by narcolepsy, sleep apena, and shift work sleep disorders.
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What can hypersomnia be a sx of?
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Can be a symptom of narcolepsy, depression, sleep apnea, restless leg syndrome.
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What can insomnia be a sx of?
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Can be a symptom of depression, jet-lag, stress, excessive caffeine or alcohol use, night shifts
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disruptive behaviors that arise due to arousals from REM sleep or partial arousals from Non-REM sleep, include bed-wetting, nightmares, night terrors, sleep-walking, and confusional arousals.
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parasomnia
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What is sleep apnea?
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a pattern of interrupted breathing (pauses, or low breathing) during sleep. Each pause in breathing, is called an apnea and can last from a few seconds to minutes, and may occur 5 to 30 times or more an hour. Each abnormally low breathing event is called a hypopnea. Most common form is Obstructive Sleep Apnea.
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What is restless leg syndrome?
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unpleasant sensation in one or both legs coupled with an urge to move them to obtain relief . Sensations are brought about by quiescent states. Results in constant leg movement and fragmented sleep at night.
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What is narcolepsy? What is thought to cause it?
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a sleep disorder that affects mainly men. Cardinal features include, excessive daytime sleepiness, cataplexy (episodes of sudden loss of muscle tone, usually triggered by emotions), a disrupted night-time sleep, hypnagogic hallucinations and sleep paralysis. Frequent “REM attacks” where a person enters REM sleep from the waking state. Can last from 30 sec to 30 min. Onset of sleep is abrupt and accompanied by cataplexy. Genetic disorder related to a mutation in the orexin-2 gene. Orexin promotes wakefulness. The brains of narcoleptic dogs and also of patients suffering from narcolepsy are deficient in orexins.
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Genetic disorder related to a mutation in the orexin-2 gene
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Narcolepsy
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What is cataplexy?
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episodes of sudden loss of muscle tone, usually triggered by emotions
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What causes sleep apnea?
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as sleep deepens, the airway muscles in the throat relax to the point of collapse, closing the airway. This prevents breathing, which causes arousal from sleep and prevents
the sufferer from entering the deeper stages of slow wave sleep. |
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Sx of carotid dissection and injury of adjacent sympathetic fibers
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Horner's syndrome (ipsilateral) due to the damage to superior cervical ganglion
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Possible sx of acute ischemic stroke caused by injury of R carotid artery (ie., from a chokehold)
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Gait instability; ptosis; headache; anisocoria (R pupil more constricted); mild L weakness of arm, face, and leg
Damage to cortical areas AND sympathetics carried along carotid |
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What happens in carotid artery dissection?
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Blood flow opens pocket between elastic and adventitia layer, then blood clots, causing thrombosis and narrowing.
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Where is carotid a. most likely to dissect?
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Base of skull/petrous temporal region where the carotid arteries are attached to the bone.
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What is the most sensitive imaging technique for ischemia?
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Diffusion tensor weighted imaging
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Spinal level of carotid bifurcation
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C3 or C4
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What happens to the sympathetics at the level of carotid bifurcation?
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They split and some follow external carotid (innervate sweat glands and vessels of face). Other following the internal carotid go on to innervate eye
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Most common cause of horner syndrome
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Cervical injury
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Treatment for traumatic carotid a dissection, presenting with focal ischemic deficits
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Systemic anticoagulation, intensive monitoring for complications like cerebral edema
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Treatment for traumatic carotid a dissection, presenting with complete carotid occlusion
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medical management, possible decompressive craniectomy for mass effect/elevated ICP
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If distal weakness is greater than proximal weakness, what is this suggesting?
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Something that affects nerves
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Sx and causes of Guillain-Barre syndrome?
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Often follows a minor infection or vaccine reaction.
Autoimmune disease where myelin in peripheral nerves is attacked, leading to tingling, then weakness, and eventually paralysis requiring respiratory ventilation. Full recovery is expected if treated. |
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Ramsay Hunt syndrome
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painful rash around the ear that occurs when the varicella zoster virus infects a nerve in the head. the virus is believed to infect the facial nerve near the inner ear. This leads to irritation and swelling of the nerve. Sx of Bells Palsy - weakness of one side of face
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synkinesis
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nerve growing back to wrong areas ; may cause inappropriate responses, such as tears when laughing or chewing (crocodile tears). Some other people may experience blinking of the eye when they talk or chew food.
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Sensory ganglion for facial nerve
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geniculate
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In bells palsy and other peripheral facial palsies, there is a/an _________ paralysis of what part of face?
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ipsilateral; upper and lower (lower only would be central)
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In a corticobulbar tract lesion above the pons, there may be a/an __________ paralysis of only lower face
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contralateral
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If Weber test is heard best in the affected ear, hearing loss is likely of __________ type; wherease if it's heard best in normal ear, it's likely of ______ type.
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conductive; sensorineural
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What causes Ramsay Hunt syndrome?
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Varicella-zoster virus that leads to inflammation of CN 7, resulting in inflammatory response (paralysis of one side of face)
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Bell's palsy is by definition _________
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idiopathic
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Swelling/Inflammation of geniculate ganglion (which sits in bone that doesn't allow for swelling) can cause _______
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Bell's palsy, an acute compressive neuropathy of facial nerve, and transient impairment of function. The nerve can recover.
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Onset of bells' palsy is ________ in most cases
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rapid
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If the forehead musculature is not affected by palsy, what is suspected?
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Central lesion --> workup for stroke
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T/F Vesicular lesions will be seen on auricle in Ramsay Hunt Syndrome
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T (But NOT in bells palsy)
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