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AROUSAL
Arousal is a physiological and psychologicalstate of being awake
It involves the activation of : 1.reticular activation system
2.autonomic nervous system
3.endocrine system
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Actvation of these 3 systems
leads to 1.Increase heart rate
2.Blood pressure
3.Sensory alertness
4.Mobility
5.Readiness to respond
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Arousal system
1.Originates from brain stem with connectonsextending throughout the cortex
2.Connections are based on neuro transmittersA.Acetyl choline
B.Norepinephrine
C.DopamineD.serotonin
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Arouasl is imporatant in
regualting. 1.consciousness
2.Attention
3.Information processing
4.Mobility
5.Flight or fight response
6.Sexual activity
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Yerkes-Dodson law
Shows the relationship between arousal and
performance
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http://images.google.com/imgres?imgurl=http://www.lboro.ac.uk/departments/hu/groups/sleep/sleep.jpg&imgrefurl=http://www.lboro.ac.uk/departments/hu/groups/sleep/telegr.htm&h=514&w=634&sz=138&hl=en&start=1&tbnid=3Se511XYAjcwHM:&tbnh=111&tbnw=137&prev=/images?q=sleep&gbv=2&ndsp=18&svnum=10&hl=en&sa=N -
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SLEEP
Sleep is as critical to survival as eating&drinking
It has an on signal & offsinal
Sleep is not a unitary process
Circardian rhythm
Sleep deprivation results in hallucinations
Signals thought to be initiated internally Manipulation of external cues has little effect
on the sleep awake cycle
http://images.google.com/imgres?imgurl=http://www.lboro.ac.uk/departments/hu/groups/sleep/sleep.jpg&imgrefurl=http://www.lboro.ac.uk/departments/hu/groups/sleep/telegr.htm&h=514&w=634&sz=138&hl=en&start=1&tbnid=3Se511XYAjcwHM:&tbnh=111&tbnw=137&prev=/images?q=sleep&gbv=2&ndsp=18&svnum=10&hl=en&sa=N -
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Blood factor & sleep
Sleep served torestore neural energy
depleted by fatigue
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Toxine theory & sleep
During waking hours fatigue toxinsaccumulate and when these toxins exceed agiven optimum level they trigger sleep
It is said that fatigue signal is in blood
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Neural factor and sleep:
( study by Bremer in 1935) Surgically removed sensory inputs to the
brain and observed resulting EEGs recorded
from cortex
Encephale isole-cut between brain stemand spinal cord
1.all sensory input was eliminated from belowneck
2.EEG activity still revealed normal sleep wake patterns
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Cerveu isole
1.Upper part of the brain stem and mid brain
level2.Optic and olfactory nerves left intact
3.Cut indeed abolish waking activity
4.Thes e indicate that sleep wake cycle dependsupon neural input from sensory systems
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Cut at midbrain level reduces the amount ofsensory stimulation reaching the cortex
It detaches connection from other parts ofbrain stem
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Wake center
Donald Lindsley-midbrain reticular lesion-abolished wakefulness
Moruzzi& magoun
electrical stimulation of
midbrain reticularformation wakefulness
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Wake center
1.sensory input is not necessary to maintainsleep wake cycle
What is signal? Wake center
1. midbrain reticular formation
2.center turns wakefulness on3.when damaged it turns
wakefulness off
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The neural mechanism of
sleep Michael Jouvet
1.passive theory-sleep is a passive
phenomenon ,like slowing a car Sleep is caused by activity in the wake center
dying out because of fatigue
Active theory-sleep is caused by sleep areaactively inhibiting wake area
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Sleep circuit
In order to be a sleep circuit it should ful fill
It must produce sleep when stimulated
Must produce wakefulness when removed Hess & others found that low frequency
electrical stimulation in the medial thalamus-sleep
Subsequent studies-sleep control notconfined to the medial thalamus only
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Other areas involved in
sleep 1.non specific projection nuclei of thalamus
2.preoptic area in the hypo thalamus
3.several areas in the lower brain
A. pontine reticular formation
Raphe nucleus
Stimulation in all these areas -sleep
Lesion in preoptic area - insomnia
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Sleeping and EEG pattern
Sleep is not an unitary process
It has different depths and stages
Analysis is possible by distinct EEG activity
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awaken brain -EEG pattern
awaken brain
1.show very fast activity 20-25 cps (beta waves)
2.awaken neurons are active in a randomfashion
3.The fluctuations in voltage are so out of phasethat they tend to cancel one another out andproduce desynchronized low amplitudewaves
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Brain falls asleep
Pattern of activity undergoes a pronouncedtransformation
Waves become much larger and much slower Moves from 8 to 10 per second (alpha)
As person relaxes 2 or 3 cps (delta)
Then the person falls into deep sleep
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Slow wave sleep -80% of sleeping hours
20%-paradoxical sleep
Paradoxical sleep-brain shows waking state
even though body remains asleep
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During paradoxical sleep there is fast,desynchronized,low amplitude activity incortex and most of subcortex
Exception is hypocampus which shows aslow regular rhythm known as theta waves
The body is even more relaxed during
paradoxical sleep than during slow wavesleep,as evidenced by the reduction in muscletone
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Its very harder to wake a person fromparadoxical sleep than from slow wave sleep
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Dreaming & EEG.
During paradoxical sleep that dreamingoccurs(Nathaniel kleitman&collegues)
Dreaming is marked by fast low amplitudeEEG activity in the cortex
Eye balls move during dreaming
Rapid eye movement sleep_ the stage ofsleep where eyeball move as if a person werefollowing a moving object with his eyes
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Most people awakened during REM sleepreport dream
This does not mean that dreaming onlyoccurs at paradoxical sleep
Dreaming also occur during slow wave sleep
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Musle relaxation
It may serve as an important safety device
Apparently the limb body during paradoxicalsleep reflects an active inhibitory mechanismin the brain that may protect determinesfrom acting out their dreams
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Behavioral nightmares
Jouvet damage to locus of coeruleusproduce behavioral night mares
The eyes of the cat in the middest of thisnightmare are close d and its behavior has norelationship to external events
The cat becomes extremely active
It hisses and claws as if acting out a dream
N l t l f d i l l
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Neural control of paradoxical sleep
and slow wave sleep-Jouvet
Jouvet concentrated onthe neural control of sleep
He given special attentionto brain stem
His subjects were cats ascats shows both types ofsleep
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Paradoxical sleep-Jouvet
During paradoxical sleep cats show uniquespike ie;patterns reffered to as PGO spikes
According to Jouvet
Paradoxical sleep is controlled by pontinereticular formation (nucleus reticularis pontiscaudalis)
Lesion abolish REM sleep
Stimulation induce REM sleep
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Slow wave sleep
Slow wave sleep is controlled by the area inbrain stem raphe nucleus
Lesion - abolish slow wave sleep
Stimulation - induce slow wave sleep
Slow wave sleep depends on both raphenucleus & its interaction with the cortex
Paradoxical sleep primarily depend upon thepontine reticular formation
Raphe neucleus and reticualr formation
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Raphe neucleus and reticualr formation
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Cortex and slow wave sleep
Animal CNS is incomplete at birth ,show onlyparadoxical activity during sleep
Paradoxical activity in the brain stem
As cortex develops slow wave activityappears during sleep
Eg:pigs neural development including cortexis virtually complete at birth
Pigs show both paradoxical sleep and slowwave sleep at birth
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Chemical codes for sleep
Raphe nucleus-serotonin(neuro transmitter)
Serotonin control slow wave activity
Elevating serotonin level will result inincreased sleep time at day time for thenormal animals
Elevated serotonin level but lesion raphenucleus serotonin compensate for lesion andrestore normal slow wave activity.
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Pontine reticualr formation
and chemical codes Pontine reticular formaton (areas related with
paradoxical sleep)- contain norepinephrine
Elevating norepinephrine increased daytime paradoxical sleep
Elevating norepinephrine by lesioningpontine reticuar pormation-compensate for
pontiner eticular formation &restoresparadoxical sleep
Interaction between slow wave
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Interaction between slow wave
sleep ¶doxical sleep
Both sleeps are under the control of differentneural areas and chemical processes
Paradoxical sleep depends n some minimalamount of slow wave sleep
Eg;eliminating slow wave sleep by lesioningRaphe nucleus abolish paradoxical sleep
Lesioning of pontine reticular formation doesnot have any effect upon slow wave sleep
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Conclusion -Jouvet
He arrived at a hypothesis to explain theinterrelationship between the 2 types of sleep
Postulated that during slow wave sleep serotonin metabolized
Its metabolized by the Raphe nucleus
And its break down products prime thepontine reticular formation
It release norepinephrine and produceparadoxical sleep
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Complicating pictures
It is not complete explanation for sleep
Acetyl choline too has pronounced effects onsleep &wake
When acetyl choline injected into preoptic area,pontine reticular formation it affected sleep andwake
Serotonin source of slow wave sleep
Depletion serotonin level disrupts sleep
But animals recovers noramal pattern of sleepthough serotonin level remain below normal
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Neural mechanism that coordinate the cyclebetween sleep and wake remain as openquestion
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DREAM
Human have a strong need to dream (studies)
The function of dream is still not clear
Roffwarg has theorized that paradoxical sleep hasan important adaptive function
Stimulates neural growth during formative periods
He explained why infants show more paradoxical
sleep than adults
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REM rebound-sleep experiment
An individual deprived of dreaming becomesirritable and when finally allowed to sleepshows a significant increase in paradoxical
sleep as if making up for lost dreams
The compensatory dreaming followingdeprivation is known as REM rebound
Subject behaves like a deprived organism Subjects becomes irritable &confused
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They have difficulty in concentration
They undergo memory lapses
And develop strong appetite for food
Then finally allowed to sleep
They dream an abnormal amount as much as60%more than normal
Then finally returns to normal NB: (subject was awakened immediately
upon slipping into paradoxical sleep)
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Developmental implications of
dreaming Children spent moretime in paradoxicalsleep than adults
Children-50%
Adults-20%
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Experts studied
developmental implicationsof dreaming
Howard Roffwarg and collegues
David kretch and collegues
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Howard and collegues .
Dreaming is related with mental growth anddevelopment
Evidence shows that stimulation fromexternal environment influences growthduring maturation
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David kretch & collegues
Rats reared in enriched sensory environmentshow larger brains than those reared in animpoverished sensory environment.
Dreaming is a form ofself stimulation.
Dreaming promote the growth of the brainduring the early formative years.
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Dreaming and mental illness
The major study is ofDement
Study was on cats
Dement injected parachlorophenylalanine &depleted serotonin(which directly initiateslow wave sleep and then paradoxical sleep)
Depletion resulted in general decrease in
sleep
Paradoxical sleep spilled over intowakefullness
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First PGO spikes appeared in awaken state
2nd dream like state appeared in awaken state
Cats perked their ears &struck out at objects
that werennt there They were like hallucinating
These cats(Dements cats)didnt shown
rebound effect Human schizophrenics also dont have
rebound effect
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It can be abolished by administeringchlorpromazine
Chlorpromazine is the effective medicine forschizophrenia today
Even when we cant say that shizophrenia isthe result of depleted serotonin levels in brain
Hallucinating behavior spills over to wakinghours
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Role of serotonin in schizophrenia remain anopen & controversial question
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Sleep disorders- insomnia
20% of US population experience sleepdisorders
Insomnia-inability to sleep
Short tern insomnia-stress,drinking ,toomuch coffee etc
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prevention
Improving sleep habbits
Avoiding stimulants
Avoid taking sleepin pills
More serious insomnia is associated withpsychiatric disorders(depression)
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Sleep apnea
Interrupted breathing during sleep
A person suffering from sleep apnea mayawaken 100s of times during the night
Results in no slow wave sleep &less time inREM sleep
These patients are chronically tired
in the day time and often suffer fromdepression
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Sometimes sleep apnea leads to suddendeath
Airway collapses during breathing &thenblocking air flow
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Restless legs syndrome
Its a common problem
Familial disorder
Unpleasant crawling
Prickling
Tingling sensations in the legs andfeet
Urge to move about for relief
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Narcolepsy
Characterizd by frequent REM sleep attacksduring day time
They enter REM sleep from wakefulnesswithout going through non REM sleep.
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