L11: EEG Flashcards by selcan icli

What does an EEG allow us to see

Electrical activity of the brain

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How does an EEG work

White cylinders are placed over head which are connected together

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What are the advantages of an EEG

Non invasive

Not painful

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Which neurones does the EEG pick a signal from

Neurones that are close to the scalp

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What is the largest neurone in the cortex that generates the greatest activity in the brain

Cortical pyramidal neurones

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What type of neurones are cortical pyramidal neurones

Upper motor neurones

Sensory neurones

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What activity does an EEG pick up

The collected activity of neurones

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What happens to the signal when there is more synchronous activity

Bigger signal

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When do neurones fire synchronously under normal conditions

1) attaching meaning to an image

2) in sleep

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What is the brain wave on an EEG tracing for awake called

Alpha

Beta

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What are the brain waves on an EEG tracing during sleep

Theta

Delta

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Which brain wave shows synchronous activity

Delta waves during sleep

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What does synchronous mean

Neurones that are active at the same time

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What does asynchronous activity mean

Neurones that are not at the same time

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What is the definition of sleep

A reversible state or reduced consciousness

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What are the state characteristic of sleep

Reduced mobility
Reduced responsiveness to sensory inputs
Reduced cortical excitability

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What are the functions of sleep

Energy conservation

Predator avoidance

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What are the consequences of poor sleep

Impairment of cognitive performance e.g Learn and memory
Decrease mood
Altered physical health

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When we are awake what rhythms do we record on an EEG

Alpha rhythms 
Beta rhythms (awake but drowsy)

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What are the 2 types of sleep

REM sleep

Non REM sleep

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In REM sleep what rhythm do we record

Beta rhythms (desynchronised and similar to awake)

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How many stages of non-REM sleep is there

4 stages

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In stage 1 non REM sleep what rhythm do we record

Theta

In stage 2 non REM sleep what rhythm do we record

Theta
Spindles
K complexes

In stage 3 non REM sleep what rhythms do we measure

Delta rhythms

In stage 4 non-REM sleep what rhythms do we measure

Delta

In REM sleep is movement possible

Yes they can have rapid darting eyes

In REM sleep are humans easily aroused by meaningful sleep

Yes like speaking their name

What can we plot the stages of non REM sleep onto

Hypnogram

When a person sleep what is likely to happen to the stage of non rem sleep

The person will go down the non REM sleep progressively and enter stage 4 early on

What will happen to the stages of non REM sleep as the night progresses on

Person is less likely to be at non rem sleep and enters rem sleep

What happens to the duration of rem sleep as the night progresses on

Increases

Which brain structure is awake associated with

Brain stem of reticular formation

When you are awake where does info from thalamusget channeled to

Cortex

As info passes up into the brainstem which 2 groups of neurotransmitters are released

Ach | Aminergic

What does ach influence

The thalamus

What does aminergic neurotransmitter influence

Cortex

In REM spleen what neurotranmitters are released

Ach only

Why do we get paralysis of muscles in rem sleep

Because the cortex is not able to send information from the motor cortex to activate skeletal muscle

In non rem sleep what are the state of neurotransmitters

Decrease in ach and aminergic

What part of the brain in non rem sleep is acitve

VLPO

What is VLPO

A small nucleus of hypothalamus

What are the 3 factors that induce sleep

Waking time Physical activity Circadian rhythms

When we wake up early why do we go to sleep early

Due to accumulation of adenosine

What does adenosine act on

Adenosine receptors

What is caffeine

An adenosine antagonist

What structure in the brain determines the circadian rhythms

Suprachiasmatic nucleus

What is the suprachiasmatic nucleus part of

Hypothalamus

What does the supra chiasmatic nuclues receive an input from

Retinal cell

What is sleep apnoe

Disruption to sleep due to breathing

What is insomnia

A lack of sleep disorder

What occurs in major depressive disorder in terms of sleep

No stage 3 or 4 non rem sleep but more rem sleep

What is REM sleep disorder

People in REM sleep do not have loss of muscle tone so they act out their dreams in REM sleep

What is the presentation of REM sleep disorder

Limb twitching Talking Yelling Jerking

What is the underlying pathology of rem sleep disorder

Brain stem inhibition to prevent motor signals are disrupted

What is narcolepsy

Uncontrollable entry to REM sleep i.e person goes from awake to REM sleep in an instance with loss of of muscle tone

What are the causes of narcolepsy

1) orexin is produced in the hypothalamus that connects to groups of neurones that produce ach and amines to stabiles wakefulness 2) few orexin contain neurones in narcolepsy cause a defective flip flip