Sleep (Lecture 10) Flashcards Preview

Psych 3 > Sleep (Lecture 10) > Flashcards

Flashcards in Sleep (Lecture 10) Deck (52):
1

What is sleep?

-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

2

EEG (electroencephalogram

-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

3

wakefulness and stages of sleep are characterized by.....

-different patterns of brain activity

4

Awake and Alert

-Beta activity
-13-30 Hz
-desychronized

5

Awake and Relaxed

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

6

Stage 1 Sleep

-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

7

Stage 2 Sleep

-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

8

Slow Wave sleep (SWS)

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

9

Stage 3 sleep

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

10

stage 4 sleep

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

11

Delta Waves

-show oscillations of ~1 Hz

12

down state

-neurons are silent
-may reflect rest for cortical neurons

13

up state

-neurons show burst of activity that is highly synchronized

14

REM sleep

-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

15

Paradoxical SLeep

-EEG shows desychronized brain activity reminiscent of wakefulness

16

Sleep Cycle

-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

17

Stage 1 physiological changes

-muscle activity reduced
-occasional muscle twitch

18

Stage 2 Physiological changes

-breathing and heart rate slows
-decrease in body temperature

19

SWS Physiological changes

-slow rhythmic breathing
-limited muscle activity

20

REM Physiological changes

-rapid eye movement
-muscles relax
-breathing is rapid and shallow
-heart rate increases
-sexual tissue engorges

21

Rate of blood flow during REM

-high in visual association cortex
-hallucinations/dreams?
-low in primary visual cortex

22

Eye movements during REM

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

23

Particular brain activity during dreams

-cortical and subcortical motor mechanisms active when dreams involve movement
-temporal lobe activity when dreams involve speech

24

Why do we sleep? Adaptation view

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

25

Why do we sleep? Not necessarily for adaptation view

-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

Why do we sleep? general view

-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

What is most important for optimal brain activity?

-slow wave and REM sleep
-these stages comprise more of total sleep following deprivation

28

Brain resting during sleep

-tasks that require concentration increase glucose utilization in the frontal lobes
-slow wave activity is greatest in frontal lobes during nREM sleep

29

Huber et al. (2004)

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

30

What can aid the consolidation of memories?

SLEEP!

31

declarative memories

-things you can describe
-events
-spatial relationships

32

Non-declarative memories

-things learned through experience
-how to drive a car
-recognize a face

33

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

-non-declarative

34

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:???????

-subjects without nap performed worst
-subjects with only slow wave sleep performed the same as before
-subjects that entered REM performed significantly better

35

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: ????????

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

36

Sigmund Freud (1856-1939)

-dreams are tiggered by unacceptable repressed wishes (usually sexual)
-psychoanalysis involved dream interpretation to expose and confront patients subconscious "wishes"

37

Activation-Synthesis Theory (Hobson 1989)

-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

Neurobiology of Sleep

-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

excessive sleep

-lisions of the posterior hypothalamus
-involved in wakefulness

40

difficulty sleeping

-lesions of the anterior hypothalamus
-involved in falling sleep

41

reticular formation

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

42

lesions in reticular formation

-disrupted sleep-wake cycles

43

low activity in reticular formation

-produces sleep

44

high activity in reticular formation

-produces wakefulness

45

caudal RAS nuclei

-control various aspects of REM sleep
-muscle paralysis
-rapid eye movement
-limb twitches
-EEG desychronization

46

What percentage of people report significant sleep related problems?

30%

47

Insomnia

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

Narcolepsy

-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

Cataplexy

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

50

Narcoleptics

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

51

orexin

-neurotransmitter in neurons of the posterior hypothalamus which project all over brain
-reduced orexin in CSF of narcoleptics
-important in wakefulness!

52

sleep paralysis

-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