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PSYCHOBIOLOGY > 8 - STRUCTURES INVOLVED IN SLEEP > Flashcards

8 - STRUCTURES INVOLVED IN SLEEP Flashcards

1
Q

what does SCN stand for

A

supra-chiasmatic nucleus

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2
Q

what does the SCN do

A
  • it is the pacemaker of our bodies
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3
Q

what do lesions to the SCN cause

A

disruptions to circadian rhythms

  • lesions caused experimentally in animals or by accidents in humans
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4
Q

where is the SCN located?

A
  • it is a nucleus of the anterior region of the hypothalamus
  • situated directly above the optic chiasm
  • forebrain
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5
Q

input to the SCN

A
  • connected to the retinae (retino-hypothalamic tract)
  • sensitive to light (unusual property of a brain structure)
  • but doesn’t rely on light for its circadian rhythm
  • FREE RUNNING CIRCADIAN RYTHM - has its own rhythm not dependant on other things
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6
Q

output of the SCN

A
  • signals to the pineal gland (looks like a pine cone apparently)
  • generates circadian rhythms
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7
Q

SCN firing patterns + maintained 24 hour cycle

A
  • SCN cells show circadian firing patterns (only fire when asleep)
  • firing patterns of SNC neurons remain circadian (but not entrained) - maintain a roughly 24 hour cycle
  • even without zeitgebers
  • even in a preparation outside of the body (eg SCN cell in a perry dish)
  • SCN cells generate circadian rhythms ENDOGENOUSLY (by themselves)
  • but can also retinal input which resets the biological clock = acts as a zeitgeber

firing pattern diagram

  • longer line = increased firing rate
  • no dark line = awake
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8
Q

what does activity in the SCN stimulate?

A
  • activity stimulates pineal gland
  • pineal gland produces melatonin
  • melatonin promotes sleep
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9
Q

retinal input signals + circadian rhythms

BLIND PEOPLE

A
  • light/dark cycles ‘reset’ the biological clock (zeitgeber)
  • blind people without light perception show abnormal circadian rhythms (free running)
  • treatment of blind (light insensitive) people with oral administration of melatonin
  • trick body into promoting sleep
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10
Q

overall network involved in sleep and wakefulness

A

basal forebrain
thalamic nuclei
hypothalamic nuclei (includes SCN)
brainstem nuclei

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11
Q

what brain structures are involved in wakefulness?

3

A
  • ARAS
  • basal forebrain
  • locus coeruleus
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12
Q

locus coeruleus

A
  • means the blue area
  • promotes wakefulness
  • produces noradrenalin (NT) (from glucoceroulous?)
  • virtually no noradrenalin released during sleep
  • located in the brain stem
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13
Q

what brain structures are involved in non-REM sleep

2

A
  • basal forebrain

- raphe nuclei

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14
Q

what does the basal forebrain do in non-REM sleep

A
  • most neurons involved in increasing alertness
  • but some involved in triggering SWS
  • stimulation = can induce SWS
  • lesion = can prevent SWS
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15
Q

what does the raphe nuclei do in non-REM sleep?

A
  • produce serotonin
  • promote non-REM sleep
  • shows non-REM sleep is not a passive default state in absence of environmental stimulation
  • as brain actively generates so these nuclei play a role
  • located in the brain stem
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16
Q

what brain area is involved in REM sleep?

1

A

pontine nuclei

  • control REM sleep
  • stimulation = triggers REM sleep
  • lesion = prevents REM sleep
  • lesion of nearby nuclei prevents REM paralysis (animals will get up and act out dreams -assumed anyways)
  • produce acetylcholine
  • enhanced levels of ACh during REM
  • ACh ‘activates’ the brain (neuromodulator)
  • ACh involved in learning (eg in Alzheimer’s ACh is severely reduced)
17
Q

what areas are positively correlated with REM

5

A
  • pons
  • amygdala
  • thalamus
  • parietal operculum
  • ACC (anterior cingulate cortex)
  • areas that increase in activity the longer we stay in REM
18
Q

what areas are negatively correlated with REM

2

A
  • prefrontal cortex (planning and rational thought)
  • posterior parietal cortex
  • areas rhat decrease in activity the more we stay in REM
19
Q

similarities of REM sleep and schizophrenia

A
  • lack of prefrontal activity in REM sleep
  • is schizophrenia a form of ‘waking dream state’?
  • only a hypothesis, not a fully theory
20
Q

what happens when we cut through the pons?

A
  • PMT = damaged - REM no longer possible
  • raphe nuclei = damaged (those that aren’t can’t reach their target higher in the brain) - no non REM sleep
  • might be some light sleep but mainly near constant wakefulness
21
Q

why is the amygdala positively correlated to REM sleep?

A
  • associated with negative emotions
  • alert to danger
  • more active the longer we stay in REM as we’re vulnerable
22
Q

which structure releases melatonin

A

pineal gland

23
Q

nuclei in the pons and medulla which actively paralyse the body
by lowering the muscle tone of skeletal muscles (hence aka REM atonia)

PSYCHOBIOLOGY (29 decks)

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