Problem 6 Flashcards

1
Q

Waking

Stage W

A

Alpha and Beta-activity

–> Beta activity is desynchronized

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2
Q

Desynchrony

A
  • reflects the fact that many different neuronal circuits are actively processing information
  • occurs when a person is alert
    • -> Beta-activity
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3
Q

Stage 1 sleep (NREM 1)

A

Theta-activity

--> firing of neurons in the neocortex is becoming more synchronized 

Transition between sleep and wakefulness

(10min)

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4
Q

Stage 2 Sleep (NREM 2)

A

Theta activity

Sleep spindles: play a role in consolidation of memories

K-complexes: triggered by noises

(15 min)

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5
Q

K-complexes

A
  • triggered by noises/occur in response to a stimulus
  • large waveforms in EEG
  • forerunner of delta waves
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6
Q

Sleep spindles

A

play a role in the consolidation of memories

 --> short bursts of waves
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7
Q

Stage 3 Sleep (NREM 3)

Slow wave sleep

A

Delta-activity

deepest stage of sleep

 - -> only loud noises can cause people to wake up 
 - -> when woken up, people are groggy and confused

(60 min)

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8
Q

REM-Sleep

A

Theta and Beta-activity

person is paralyzed at this stage, because spinal and motor neurons are strongly inhibited
–> one does not react to loud noises, just meaningful stimuli (e.g. name)

when woken up, people are alert and attentive

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9
Q

Functions of slow wave sleep

A
  • brain rests
  • Recovery
  • -> regions that had highest waves (most active) during wakefulness, have the highest waves during slow wave
  • low metabolic rate
    • -> permits restorative mechanisms to destroy free radicals
  • facilitates the consolidation of declarative memories
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10
Q

Effects of sleep deprivation

A
  • cognitive abilities are effected
    • -> perceptual distortions
    • -> hallucinations
    • -> trouble concentrating
  • one never regains all the sleep one lost
  • causes increase in free radicals
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11
Q

Free radicals

A
  • unstable molecules that can damage the cells in the body
    • -> form when atoms or molecules gain or lose electrons
  • accumulate during waking
  • contain at least one unpaired electron
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12
Q

Oxidative Stress

A
  1. When the body uses oxygen it produces free radicals as a by - product
  2. Free radicals then bind with the oxygen molecules which results in them splitting into single atoms

–> this causes oxidative stress

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13
Q

Fatal familial insomnia

A

damage to portions of the thalamus

–> disappearance of slow wave sleep + only brief episodes of REM sleep without paralysis

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14
Q

Functions of REM Sleep

A

promotes brain development

  • facilitates the consolidation of nondeclaractive memories
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15
Q

Rebound Phenomenon

A

After sleep deprivation

 --> when permitted to sleep normally there is a higher-than normal percentage of REM sleep in the recovery night
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16
Q

Nondeclarative memories

A

Memories gained through experience + practice

e.g.: learning to drive a car, recognizing a face, throw a ball

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17
Q

Declarative memories

A

Memories of past episodes of ones life, memories one can talk about

Memories of the relationships between a stimuli or events

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18
Q

Adenosine

A
  • sleep promoting substance that accumulates during waking and is destroyed during sleep
  • plays the primary role in the control of sleep
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19
Q

Neural control of sleep

Procedure

A
  1. Prolonged wakefulness results in a decrease of glycogen
    • -> fuel for neurons, produced by astrocytes
  2. Increase of extracellular adenosine
    • -> inhibitory effect on neural activity
  3. Accumulation of adenosine promotes sleep
  4. During slow wave
    • -> neurons rest
    • -> adenosine decreases
    • -> Astrocytes renew the stock of glycogen
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20
Q

Role of caffeine

A
  • antagonist
  • blocks adenosine receptors to prevent sleepiness
  • only works when there is actual sleep deprivation
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21
Q

Neural control of arousal

–> What are the systems involved ?

A

Five systems of neurons are of importance for alertness and wakefulness

 - -> Acetylchonergic System 
 - -> Norodrenergic System 
 - -> Serotonergic System
 - -> Histaminergic System 
 - -> Orexinergic System
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22
Q

Acetylchonergic System

A
  • 2 groups of ACh neurons are located in pons + basal forebrain
  • 1 group is located in the medial septum
    • -> controls the activity of the hippocampus
    => high levels of ACh in those regions during
        - -> REM
        - -> waking
23
Q

Norodrenergic System

A
  • located in the locus coeruleus ( dorsal pons )
  • stimulation causes immediate waking ( vigilance )=> high firing rate during
    –> waking
24
Q

Serotonergic System

A
  • located in the raphe nuclei ( reticular formation )
  • stimulation causes locomotion and cortical arousal=> high firing rate during
    –> wakefulness
25
Q

Histaminergic System

A
  • located in the tuberomammilary nucleus ( TMN ) of the thalamus
  • axons project amongst other regions to cerebral cortex and basal forebrain
    • -> increase of cortical arousal due to the release of ACh
    => control of wakefulness is shared with other neurotransmitters
26
Q

Orexinergic System

A
  • located in the lateral hypothalamus
  • axons project to all of the regions where the other systems for alertness are located

–> has an excitatory effect on all of the other regions, thus causes the release of their neurotransmitters

=> high firing rate during wakefulness

27
Q

Homoestatic control

A

Mainting the balance of sleep/wake at an optimal level

28
Q

Allostatic control

A

reactions to stressful events, that serve to override homoestatic control

ex.: in case of danger one is more alert/high attentive even if one is sleep deprived

29
Q

Cicardian Control

A

Entraining periods of sleep to particular portions of light/dark cycle

30
Q

Preoptic Area

A
  • suppresses the activity of the arousal neurons when active

- -> most involved area in sleep

31
Q

Flip Flop circuit

A

refers to reciprocal inhibiton - determines when we wake and when we sleep

 - -> on: sleep neurons are active, inhibit wakefulness neurons 
 - -> off: wakefulness neurons are active, inhibit sleep neurons

=> mutually inhibitory, impossible that they’re active at the same time

32
Q

REM Flip Flop

A
  • controls cycles of Rem Sleep and Slow wave sleep

- REM on + off regions are interconnected by GABA neurons

33
Q

Primary Insomnia

A

Difficulty falling asleep after going to bed or waking during the night

34
Q

Secondary Insomnia

A

Inability to sleep due to another mental/physical condition such as pain

35
Q

Sleep Apnea

A

Inability to sleep and breathe - caused by an obstruction of the airway

 --> particular form of Insomnia
36
Q

Nonpharmalogical treatment

A

Cognitive behavior therapy, changes in sleep hygiene, etc.

37
Q

Pharmalogical treatment

A

drugs (hypnotics)

–> Agonists at the GABAa Receptor

38
Q

Narcolepsy

A

sleep at inappropriate times

39
Q

Sleep attack

A

overwhelming urge to sleep caused by boring conditions

 --> symptom of narcolepsy
40
Q

Cataplexy

A
  • Sustaining varying amounts of muscle weakness, sometimes completely paralyzed (inhibition of the motor neurons)
  • caused by strong emotions
    • -> symptom of narcolepsy
41
Q

Sleep paralysis

A

Inability to move just before the onset of sleep, or on waking in the morning

42
Q

Hypnagogic Hallucinations

A

Dreaming, while lying awake, paralyzed

–> lucid dreaming

43
Q

Physiological basis of Narcolepsy

A
  • caused by a mutation of orexin-B receptor
    • -> destruction or complete loss of orexin neurons
  • disorder that causes immune system to attack and destroy orexin secreting neurons
44
Q

REM sleep behavior disorder

A

failing to exhibit paralysis during REM

–> opposite to cataplexy

45
Q

Cicardian Rhythm

A

Cycle of approximately 24h, that controls sleep/wake, physical activity and body temperature

 --> located in the SCN
46
Q

Zeitgeber

A

Illumination/light keeps the inner clock adjusted to 24h

 --> Light synchronizes the endogenous rhythm
47
Q

Suprachiasmatic Nucleus (SCN)

A
  • provides the primary control over timing of sleep cycles

- -> receives input from the visual system

48
Q

Melanopsin

A

Special photoreceptor that provides information about the level of light that synchronizes cicardian rhythms

 --> present in the ganglion cells
49
Q

Ganglion cells

A

Neurons that transmit information from the eyes to rest of the brain

50
Q

Pineal Gland

A
  • controls annual rhythms

- secretes melatonin

51
Q

Melatonin

A
  • secreted during the night
    ex. : during longer night (winter) - more secretion
  • can alter the cicardian rhythm
52
Q

Effects of shift work and jet lag

A
  • disparity between internal rhythm + external environment
53
Q

Solution to jet lag and shift work

A

providing Zeitgebers at appropriate times

 ex.: exposure to bright lights
54
Q

Molecular Clock in mice

Procedure

A
  1. Proteins clock + cycle bind together and form a dimer
  2. Dimer binds to DNA
    • -> enhances ttranscription of the genes Period + Cryptochrome
  3. Per + Cry bind together as a complex
    • -> inhibits activity of the Clock/cycle dimer
    • -> slows down the transcription of per + cry
  4. Per + Cry proteins eventually break down
    • -> inhibition of the dimer stops
  5. Whole cycle starts again