Sleep (Lecture 10) Flashcards

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1
Q

What is sleep?

A
  • a readily reversible state of reduced responsiveness to , and interaction with the environment
  • not readily reversible:
    • coma
    • general anesthesia
    • death
  • —> these do not qualify as sleep
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2
Q

EEG (electroencephalogram

A
  • general activity of the cerebral cortex
  • fluctuations in voltage between any given 2 electrodes
  • = excitation of cortical neurons
  • because signal must penetrate so many layers of non neural tissue = thousands of neurons must fire in unison to generate visible signal
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3
Q

wakefulness and stages of sleep are characterized by…..

A

-different patterns of brain activity

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4
Q

Awake and Alert

A
  • Beta activity
    • 13-30 Hz
  • desychronized
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5
Q

Awake and Relaxed

A

-Alpha activity
8-12 Hz
-increasing synchronicity
-more prevalent with eyes closed

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6
Q

Stage 1 Sleep

A

-theta activity
-3.5-7.5 Hz
-transition between sleep and wakefulness
eyelids slowly open and close and eyes roll up and down
LASTS ABOUT 10 minutes during first sleep cycle

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7
Q

Stage 2 Sleep

A

-some theta activity
-3.5-7.5 Hz
-sleep spindles
-12-14 Hz (beta-eque)
-short bursts 2-4 per minute
-K complexes
-sudden sharp waveforms
-1 per minute
-triggered by noises = mechanism to inhibit waking?
LASTS ABOUT !% minutes during first sleep cycle

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8
Q

Slow Wave sleep (SWS)

A

-Delta activity
< 3.5 Hz
-difficult to wake people from SWS and when awakened, report no dreaming, but may remember image or emotion

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9
Q

Stage 3 sleep

A

-some theta activity
-20-50% delta
~20 minutes in first sleep cycle

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10
Q

stage 4 sleep

A

-some theta activity
> 50% delta
-deepest sleep
~ 45 min in first sleep cycle

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11
Q

Delta Waves

A

-show oscillations of ~1 Hz

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12
Q

down state

A
  • neurons are silent

- may reflect rest for cortical neurons

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13
Q

up state

A

-neurons show burst of activity that is highly synchronized

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14
Q

REM sleep

A
  • theta activity (like stage 1,2,2)
    • 3.5-7.5 Hz
  • Beta activity (like wakefulness)
    • 13-30 Hz
  • Paradoxical Sleep
  • people awakened easily from REM sleep and report vivid dreams
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15
Q

Paradoxical SLeep

A

-EEG shows desychronized brain activity reminiscent of wakefulness

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16
Q

Sleep Cycle

A
  • sleep alternates between REM and nREM (stages 1-4) in 90 minute sleep cycles
  • in avg. 8 hours of sleep you experience 4-5 bouts of REM sleep
  • as night progresses stage 2 and REM sleep are prolonged and SWS is reduced
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17
Q

Stage 1 physiological changes

A
  • muscle activity reduced

- occasional muscle twitch

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18
Q

Stage 2 Physiological changes

A
  • breathing and heart rate slows

- decrease in body temperature

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19
Q

SWS Physiological changes

A
  • slow rhythmic breathing

- limited muscle activity

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20
Q

REM Physiological changes

A
  • rapid eye movement
  • muscles relax
  • breathing is rapid and shallow
  • heart rate increases
  • sexual tissue engorges
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21
Q

Rate of blood flow during REM

A
  • high in visual association cortex
    • hallucinations/dreams?
  • low in primary visual cortex
22
Q

Eye movements during REM

A

-seem to match eye movements that would be made while watching their dream

23
Q

Particular brain activity during dreams

A
  • cortical and subcortical motor mechanisms active when dreams involve movement
  • temporal lobe activity when dreams involve speech
24
Q

Why do we sleep? Adaptation view

A

-sleep gives organism safety from danger or predation when they are not suited to puse food or other biological needs

25
Q

Why do we sleep? Not necessarily for adaptation view

A
  • Indus dolphin of Pakistan
  • this dolphin does not sleep in a safe place with no predation
  • dolphin can not stop swimming while sleeping because of dangerous current and debris
  • sleeps 7 hours per day via 4-60 second microsleeps
26
Q

Why do we sleep? general view

A
  • not just to rest our bodies
    • sleep deprication does not interfere with ability to exercise
  • sleep might rest the brain
    • sleep deprivation affects cognitive abilities
      - perceptual distortions
      - hallucinations
      - trouble concentrating
27
Q

What is most important for optimal brain activity?

A
  • slow wave and REM sleep

- these stages comprise more of total sleep following deprivation

28
Q

Brain resting during sleep

A
  • tasks that require concentration increase glucose utilization in the frontal lobes
    • slow wave activity is greatest in frontal lobes during nREM sleep
29
Q

Huber et al. (2004)

A

-people that learned a motor task just before going to sleep showed heightened slow wave activity in cortex activated by task

30
Q

What can aid the consolidation of memories?

A

SLEEP!

31
Q

declarative memories

A
  • things you can describe
    • events
    • spatial relationships
32
Q

Non-declarative memories

A
  • things learned through experience
    • how to drive a car
    • recognize a face
33
Q

REM is important for the consoliation of what type of memory?

A

-non-declarative

34
Q

EXPERIMENT
Participants learned non-declarative visual discrimination task
1. one group allowed a 90 minutes nap (EEG used to determine who got REM sleep)
2. other group allowed no nap
tested 9 hours later resulted in:???????

A
  • subjects without nap performed worst
  • subjects with only slow wave sleep performed the same as before
  • subjects that entered REM performed significantly better
35
Q

EXPERIMENT
Participants learned a list of words (declarative) or trace a pattern on paper while looking in a mirror (non-declarative)
1. one group allowed a 1 hour nap 9 with no REM)
2. other group was not allowed a nap
tested 6 hours later, results: ????????

A
  • slow wave sleep increase performance on declarative task but not non-declarative task
  • —>need slow wave sleep in order to consolidate memories!!!!!
36
Q

Sigmund Freud (1856-1939)

A
  • dreams are tiggered by unacceptable repressed wishes (usually sexual)
  • psychoanalysis involved dream interpretation to expose and confront patients subconscious “wishes”
37
Q

Activation-Synthesis Theory (Hobson 1989)

A
  • during REM brain stem circuits (pons) become activated and send information to cortex
  • cortex takes “random” activations and tries to compose a cohesive story
38
Q

Neurobiology of Sleep

A
  • two areas of the hypothalamus have problems if excessive sleep or difficulty sleeping is observed
  • Discovered by Constantin von Economo during WWI outbreak of encephalitis lethargica
39
Q

excessive sleep

A
  • lisions of the posterior hypothalamus

- involved in wakefulness

40
Q

difficulty sleeping

A
  • lesions of the anterior hypothalamus

- involved in falling sleep

41
Q

reticular formation

A
  • structure in the brain stem that sends projections to thalamus and cortex
  • electrical stimulation of reticular formation awakend sleeping cats
42
Q

lesions in reticular formation

A

-disrupted sleep-wake cycles

43
Q

low activity in reticular formation

A

-produces sleep

44
Q

high activity in reticular formation

A

-produces wakefulness

45
Q

caudal RAS nuclei

A
  • control various aspects of REM sleep
    • muscle paralysis
    • rapid eye movement
    • limb twitches
    • EEG desychronization
46
Q

What percentage of people report significant sleep related problems?

A

30%

47
Q

Insomnia

A

all disorders of initiating and maintaining sleep

  • most cases drug-related
  • sleep apnea (cessation of breathing during sleep)
  • restless leg syndrome = tension in legs that disrupts sleep
48
Q

Narcolepsy

A
  • 1/2000 people
  • severe daytime sleepiness and brief (10-15 minutes) daytime sleep episodes
  • may result from genetic mutation in a gene related to orexin
49
Q

Cataplexy

A
  • recurring loss of muscle tone during wakefulness
    • often triggered by strong emotion
    • may stem from abnormality in mechanisms that mediate REM
50
Q

Narcoleptics

A
  • go straight into REm when they fall asleep
  • experience sleep paralysis = paralysis just as falling asleep
  • hypnogogic hallucinations = dreamlike states during wakefulness
51
Q

orexin

A
  • neurotransmitter in neurons of the posterior hypothalamus which project all over brain
  • reduced orexin in CSF of narcoleptics
  • important in wakefulness!
52
Q

sleep paralysis

A
  • period of inability to perform voluntary movements either at sleep onset or upon wakening
  • may be accompanied by visual and/or auditory hallucinations and even “out of body” feelings