L11: EEG Flashcards
What does an EEG allow us to see
Electrical activity of the brain
How does an EEG work
White cylinders are placed over head which are connected together
What are the advantages of an EEG
Non invasive
Not painful
Which neurones does the EEG pick a signal from
Neurones that are close to the scalp
What is the largest neurone in the cortex that generates the greatest activity in the brain
Cortical pyramidal neurones
What type of neurones are cortical pyramidal neurones
Upper motor neurones
Sensory neurones
What activity does an EEG pick up
The collected activity of neurones
What happens to the signal when there is more synchronous activity
Bigger signal
When do neurones fire synchronously under normal conditions
1) attaching meaning to an image
2) in sleep
What is the brain wave on an EEG tracing for awake called
Alpha
Beta
What are the brain waves on an EEG tracing during sleep
Theta
Delta
Which brain wave shows synchronous activity
Delta waves during sleep
What does synchronous mean
Neurones that are active at the same time
What does asynchronous activity mean
Neurones that are not at the same time
What is the definition of sleep
A reversible state or reduced consciousness
What are the state characteristic of sleep
Reduced mobility
Reduced responsiveness to sensory inputs
Reduced cortical excitability
What are the functions of sleep
Energy conservation
Predator avoidance
What are the consequences of poor sleep
Impairment of cognitive performance e.g Learn and memory
Decrease mood
Altered physical health
When we are awake what rhythms do we record on an EEG
Alpha rhythms Beta rhythms (awake but drowsy)
What are the 2 types of sleep
REM sleep
Non REM sleep
In REM sleep what rhythm do we record
Beta rhythms (desynchronised and similar to awake)
How many stages of non-REM sleep is there
4 stages
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