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Neuro > Neuro 15: Consciousness and sleep > Flashcards

Neuro 15: Consciousness and sleep Flashcards

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1
Q

Define sleep

A

Stereotypic or species-specific posture

Minimal movement

Reduced responsiveness to external stimuli

Reversible with stimulation – unlike coma, anaesthesia or death

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2
Q

What tells you about sleep

A

EEG, EOG and EMG (muscle tone)

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3
Q

How does EEG, EOG and EMG change in stage 1&2 NREM, stage 3&4 NREM and stage 5 (REM)

A

EEG slows in stage 1&2 but increases a lot in 3&4, and is slow in REM

EOG is much slower in NREM 1&2, but like awake in 3&4 and very high peaks in stage 5 (rapid eye movement so EOG is going to be high!)

EMG reduces 1-4 and is almost nothing in REM… stops you acting out your dream

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4
Q

T/F REM is only time you dream

A

F… also during other stages but maybe less

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5
Q

How long is the sleep cycle and what is it made up of

A

Takes 90 minutes, goes through stage 1-5…. earlier on in sleep, NREM stages take up more time in the cycle

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6
Q

What is like EEG like in REM sleep

A

More like awake compared to stage 3/4

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7
Q

As well as EEG/muscular change, what other phsyioligcalt changes occur in sleep

A

Heart rate and respiratory changes— both reduce from stage 1-4, but increase into REM sleep and fluctuate a lot in REM

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8
Q

What controls sleep

A

Reticular activating system (brainstem systems which project fibres onto cortex, hypothalamus and thalamus)

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9
Q

t/f RAS allows for consciousness

A

True… kind of…. it’s necessary for consciousness but alone is not sufficient…. it’s like a dial, but it gates the activity of the cortex

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10
Q

Which brain areas promote wakefullness and sleep

A

wakefulness: lateral hypothalamus (orexin)
sleep: ventrolateral preoptic nucleus (in anterior hypothalamus)

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11
Q

Interaction of hypothalamus with the RAS

A

Orexin based lateral hypothalamus activates the recticular activating system

but the ventrolateral preoptic nucleus inhibits it (GABA)

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12
Q

How does the suprachiasmatic nucleus impact on sleep

A

It synchronises sleep with falling light levels….

CIRCADIAN SYNCHRONISATION of sleep/wake cycle.

It interacts with the hypothalamus (both the lateral nucleus, and the ventrolateral preoptic nucleus) and the RAS and with the pineal gland to release melatonin….

Linked to retina

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13
Q

Effects of sleep deprivation

A

Psychiatric and neurological together- Sleepiness, irritability, stress, mood fluctuations, depression, impulsivity, hallucinations

Neurological- Impaired attention, memory, executive function
Risk of errors and accidents
Neurodegeneration (?)

Somatic-Glucose intolerance
Reduced leptin/increased appetite
Impaired immunity
Increased risk of cardiovascular disease and cancer
Death
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14
Q

t/f sleep loss affects brain activation on fMRI

A

T

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15
Q

How can is sleep regulated (i.e. what can change if you have sleep loss)

A

Reduced latency to sleep onset

Increase slow wave (NREM) sleep as a proportion of sleep if you missed this

Or increase REM sleep after selective REM sleep deprivation

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16
Q

Function of sleep

A

Restoration and recovery – but active individuals do not sleep more

Energy conservation – 10% drop in BMR – but lying still is just as effective

Predator avoidance – but why is sleep so complex?

Specific brain functions – memory consolidation, …

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17
Q

When do dreams most often occur

A

REM sleep (but can be both), and more easily recalled then

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18
Q

What area of brain active in dreaming

A

Limbic system>frontal lobe

More about emotion than reality

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19
Q

Function of dreaming

A

Safety valve for antisocial emotions
Disposal of unwanted memories
Memory consolidation

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20
Q

Outline insomnia causes

A

Most transient cases

physiological: sleep apnea, chronic pain

brain dysfunction: depression, fatal familial insomnia (caused by pryon protein like CJD) or night working

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21
Q

Outline treatment of inoomnia

A

sleep hygiene, hypnotics (most enhance GABAergic circuits e.g. tamazepam or zopiclone) and sleep CBT

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22
Q

What is narcolepsy

A

Falling asleep repeatedly during the day and disturbed sleep during the night

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23
Q

What is hypersomnia

A

Too sleepy in the day…
due to arousal in the night disrupting sleep wake cycle:

  • sleep apnea
  • anxiety
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24
Q

Differentiate the type of disease of narcolepsy compared to insmnia

Study These Flashcards
A

narcolepsy is a disease of the actual sleep/wake pathways (primary), whereas insomnia the pathway is probably fine and it’s other factors affecting this pathway

25
What is cataplexy and when does it occur
In narcolepsy sudden, brief loss of voluntary muscle tone, often triggered by strong emotions e.g. laughter
26
T/F in narcolepsy because of the disturbed sleep, REM and NREM sleep are comensated depending on which you have less of
F: there is Dysfunction of control of REM sleep
27
Narolepsy is caused by what
Deficiency of orexin (=hypocretin)
28
What can shift work lead to
physiological processes to become desynchronised sleep disorders, fatigue and an increased risk for some conditions such as obesity, diabetes and cancer
29
Is sleep a consequence or cause of neurological disease
Could be either realy
30
Definiton of consciousness
the state of being aware of and responsive to one's surroundings
31
Elements of conscioussness
Level, content, self
32
Classify following in terms of VIGILANCE (awake behaviour, eyes open) and AWARENESS (level/content of consciousness.... richness of experience): ``` Coma General anaesthetic Locked in syndrome Veg state Dementia ```
Coma, very low for both General anaesthesia similar to coma but could have tiny bit more awareness Locked in high awareness and high vigilance (just under conscios) Veg state- high vigilance but very low awareness Dementia/minimally conscious state= fairly normal vigilance, but reduced awareness
33
Why does RF project to cortex
allowing that sensory signals to reach cortical sites of conscious awareness such frontoparietal cortex
34
Types of neurotransmitters in the RAS
RF projects to the hypothalamus, thalamus and the cortex Ventral tegmental Area (dopaminergic neurones)... this relates to reward pathway mesolimbic.... VTA in midbrain pons- Locus coeruleus (noradrenergic neurones)... this relates to pain
35
t/f consciousness arises from a partcular part of the brain
f.. it emerges as a result of cortico-thalamic transmission
36
What is important for consciousness
dynamics of neuronal activity-- integrated and differentiated HIGH INTEGRATION, LOW DIFFERENTIATION= generalised seizure (all areas of the brain doing the same thing) LOW INTEGRATION, HIGH DIFFERENTIATION= e.g. callosotomy... areas doing different things but none of this linked with each other
37
How can consciousness be measured
Give TMS and then meausure activity after with EEG You can measure how well that induced TMS travels across to other brain regions. In an awake individual, this signal will spread across brain regions (high integration) but in asleep will not (low integration) Can also see if the different brain areas to which the signal spreads process the signal differently (i.e. high differentiateion, heterogenous) or in the same way (i.e. low differentiation) Can quantify this to give PCI.... pertubational complexity index (PCI)
38
What is 'neural correlates of consciousness' referring to
The minimum neuronal mechanisms jointly sufficient for any one specific conscious experience. Primarily localized to a posterior cortical hot zone that includes sensory areas (Koch et al., 2016) i.e. where is the brain region that corresponds to a particular experience of consciousness
39
3 disorders of consciousness
Coma- Absent wakefulness and absent awareness, Vegitative state- Wakefulness but absent awareness Minimally conscious state- wakefulness with minimal awareness
40
T/F brainstem death is a disorder of consciousness
F... neither is locked in syndrome
41
Feedforword processing vs top-down recurrent processing
feed forward=subliminal or non sonscious Top dorwn is conscious access We can have top-down and bottom-up processes – there are non-conscious processes that bubble up to conscious access.
42
State the components of a coma
- can't be awakened - doesn't respond norally to painful stimulu, light or sound - Lacks normal sleep wake cycle - Does not initiate voluntary actiond
43
Which area of brain might be affected in: vegetative state locked in syndrome brainstem death
vegetative state=cortex/hemispheres (intact RAS) locked in syndrome=damage e.g. to ventral pons (motor system).... intact cortex and intact RAS brainstem death= irremediable damage to brainstem
44
In which types of strokes may visual neglect occur
parietal lobe
45
Differentiate hemianopia from visual neglect
Both involve part of the world not being seen with hemianopia this is a visual pathway problem with visual neglect this is a higher up cortical deficit often conflated as both can occur due to stroke
46
Different types of waves on EEG and what EEG monitors
Monitors level of arousal BATD: from awake to sleep Delta= in sleep. Up to 4Hz Theta= 4-8 Hz. Alpha=8-13Hz Beta=13-30 Hz (normal waking consciousness) 40Hz (gamma range) associated with creation of conscious contents via THALAMO-CORTICAL FEEDBACK LOOPS
47
When might alpha waves occur on ECG
When drowsy or relaxed
48
When might theta waves occur
Stage N1 sleep
49
When might delta waves occur
Stage N3 sleep
50
When might you get sleep spindle waves on EEG Sumarise the EEG seen during different levels of conscioussness
stage N2 sleep ``` B: Awake A: drowsy, relaxed T: N1 sleep Spindles: N2 sleep D: N3 sleep ``` REM sleep is fast and random EEG.
51
What are the components of the glasgow coma scale
1-4 for eyes 1-5 for verbal 1-6 for motor
52
Minimum GCS score and max
min is 3 | max is 15
53
Causes of coma
``` Metabolic: Drug overdose hypoglycaemia diabetes "the failures" hypercalcaemia ``` ``` Diffuse intracranial: head injury meningitis SAH encephalitis epilepsy hypoxic brain injury ``` ``` Hemisphere lesion: cerebral infarct cerebral haemorrhage subdural extradural abscess tumour ``` ``` Brain stem: brainstem infarct tumour abscess cerebellar haemorrhage cerebellar infarct ```
54
What is coma
Unrousable unresponsiveness
55
What is diffuse axonal injury
Damage to white matter tracts e.g. corpus callosum.... higher order cognitive problems due to poor integration..... can follow traumatic brain injury (e.g. after extradural haematoma etc.)
56
Which types of stroke could cause coma
Bitemporal medial thalamic infarcts or strokes to do with posterior ciruclation
57
Which types of lesions are dangerous due to basic functin
Posterior fossa lesions
58
Decorticate vs decerebrate posturing
Main difference is decorticate involves flexion at the elbow Whereas decerebrate involves extension at the elbow and pronation Decerebrate indicated involvement of the red nucleus and indicates event further down in the brainstem

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