Sleep

Question 1

What does an EEG measure?

Answer 1

→ The combined activity of a large number of similarly orientated neurons

Question 2

What does an EEG require?

Answer 2

→ synchronous activity across groups of cells

Question 3

What does the amplitude of an EEG signal depend on?

Answer 3

→ how synchronous the activity of the neurons are

Question 4

What is a large summed signal caused by?

Answer 4

→ tiny signals summed up to generate a large surface signal

Question 5

What is a small summed signal caused by?

Answer 5

→ the same amount of excitation as a large signal

→ but at irregular intervals

Question 6

What do EEG rhythms correlate with?

Answer 6

→ States of behaviours

Question 7

What is high frequency and low amplitude associated with?

Answer 7

→ Alertness and wake

Question 8

What is low frequency and high amplitude associated with?

Answer 8

→ Non dreaming sleep or coma

Question 9

What are the two theories of how rhythms are generated during sleep?

Answer 9

→ There is a pacemaker that acts as a conductor (conductor telling everyone to clap)
→ mutual excitation and inhibition and neurons sync to what other neurons are doing (people clapping at random and syncing to each other)

Question 10

What is theorised to be the pacemaker in the brain and why?

Answer 10

→ Thalamus

→ thalamic nuclei communicate with every cortical brain structure

Question 11

Describe the hypothesis for slow frequency and high amplitude rhythms during sleep?

Answer 11

→ Thalamus acts as a gatekeeper it stops information getting to the brain during sleep
(like a spinning arm in an obstacle course)

Question 12

Describe the hypothesis for fast frequency and low amplitude rhythms during wakefulness

Answer 12

→ the brain is attention grabbing to bind together regions needed for task execution

Question 13

What is sensation like in non REM sleep?

Answer 13

→ dull or absent

Question 14

What is thought like in non REM sleep?

Answer 14

→ logical

→ repetitive

Question 15

What is movement like in non REM sleep

Answer 15

→ occasional

→ involuntary

Question 16

What is sensation like in REM sleep?

Answer 16

→ vivid

→ internally generated

Question 17

What is thought like in REM sleep?

Answer 17

→ vivid
→ illogical
→ bizarre

Question 18

What is movement like in REM sleep?

Answer 18

→ muscle paralysis

→ movement commanded by the brain but not carried out

Question 19

What is temperature, heart rate, breathing and energy consumption like in non REM sleep?

Answer 19

→ Decreased temperature
→ decreased heart rate
→ decreased breathing
→ decreased brain energy consumption

Question 20

What is temperature, heart rate, breathing and energy consumption like in REM sleep?

Answer 20

→ very low temperature
→ increased heart rate
→ increased breathing
→ very high brain energy consumption

Question 21

What kind of sleep do you begin with?

Answer 21

→ non REM sleep

Question 22

When do sleep cycles repeat?

Answer 22

→ every 90 minutes

Question 23

How many minutes of non REM do you need to progress into REM?

Answer 23

→ 30 minutes

Question 24

Why do we sleep?

Answer 24

→ getting rest -cognitive performance is increased after sleeping
→ adaptation to protect themselves and conserve energy

Question 25

When you are awake what neurotransmitters are secreted and from where and what do they do?

Answer 25

→ ACh and orexin → basal forebrain and hypothalamus → increase excitatory activity and decrease synchronous firing

Question 26

When you fall asleep what drives neural activity?

Answer 26

→ thalamus

Question 27

What receptor activation promotes sleepiness?

Answer 27

→ adenosine

Question 28

What does adenosine receptor activation cause?

Answer 28

→ Decrease heart and respiratory rate | → smooth muscle tone decrease

Question 29

What are adenosine levels like during the day and night?

Answer 29

→ day - increasing | → night - rapidly drop

Question 30

What stimulates adenosine release?

Answer 30

→ nitric oxide

Question 31

What other factors contribute to sleepiness?

Answer 31

→ inflammatory factors

Question 32

What is melatonin and when is it secreted?

Answer 32

→ compound that increases when there is a reduction in light

Question 33

What is body temperature like during the day and night?

Answer 33

→ high during the day | → decreases at night

Question 34

What hormone increases at night?

Answer 34

→ Growth hormone

Question 35

What is cortisol like during the day and night?

Answer 35

→ Cortisol decreases during the day then increases before wakefulness

Question 36

What are zeitgebers?

Answer 36

→ environmental cues such as the sun

Question 37

What is the natural sleep cycle with no cues?

Answer 37

→ 24-25 hours

Question 38

Where is the suprachiasmatic nucleus?

Answer 38

→ Located between the optic chiasm at the base of the hypothalamus

Question 39

What does the suprachiasmatic nucleus do?

Answer 39

→ provides a circadian rhythm

Question 40

What happens when the suprachiasmatic nucleus is inhibited?

Answer 40

→ The cycles are irregular

Question 41

Describe how melatonin is inhibited?

Answer 41

→ Ganglion cells have a protein that is reactive to light → melanopsin ganglion cells transmit the activation to the suprachiasmatic nucleus → this inhibits the pineal gland →pineal gland is reponsible for the production of melatonin

Question 42

Describe how melatonin is produced

Answer 42

→ no activation of melanopsin at night → SCN is not activated → pineal gland is not inhibited → produces melatonin