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Which analgesics work in the central nervous system?
A-Cannabis-based drugs
B-Capsaicin
C-Non-steroidal anti-inflammatory drugs (e.g. ibuprofen)
D-Opiates (e. g. morphine)
E -Paracetamol
Answer ADE – I think
Explanation – double check with him
Sleep: an overview
What is sleep ?
• How do we sleep ?
• Circadian rhythms
How do we study sleep? How do we measure sleep
By using a polysomnogram – a test used to study sleep and diagnose sleep disorders , it makes many records of various things(parameters) that relate to sleep simultaneously
what does a polysomnogram measure in relation to sleep?
Polysomnogram = many records of sleep
• EEG (Electro-encephalogram) – brain activity
• EOG (Electro-oculogram) – eye movement
• EMG (Electro-myogram) – muscle activity
• EKG/ECG (Electro-cardiogram) heartrate and rhythm
• Airflow – breathing patterns and airflow
• Oximeter – oxygen levels in the blood
how does a polysomnogram measure different sleep parameters
Go to a sleep clinic and patient will get wired up with all these things that record you while you sleep in a laboratory naturally:
what is a potential caveat that could detract from the value of the polysomnogram?
as patient not sleeping in own bed or familiar surroundings could produce somewhat inaccurate insight into sleep
what is this a photo of?
A subject prepared for a nights sleep in a sleep laboratory – being recorded by a polysomnogram.
What is the main/ defining recording feature used in a polysomnogram?
why?
the measurements taken and changes recorded by EEG
Because it records and detects the different stages that characterise sleep
What does an EEG measure?
Measures electrical activity in your brain
How does an EEG measure electrical activity in the brain?
by placing electrodes on the surface of the scalp, often via wearing a cap over your head
what does an EEGs electrode have to stimulate through?
Electrode and brain are separated from each other as Hair, skin, tissue between your skin and your skull, your cranium, cerebral flued, lie between the brain
What do EEG signals measure?
• EEG signals are a summation of the activity of many neurons in the cortex closest to the electrode your recording from (as due to the distance between the electrode and the brain, individual neurons can’t be recorded)
EEG electrodes record the summation of all the detected changes in the surrounding neurons membrane potentials
ØSynchronized activity: large deflections (occurs if all neurons change their membrane potential at the same time in the same direction)
ØUnsynchronized activity: averages out – will only see very small changes/ deflections
What do researchers look for in EEGs ?
Patterns of synchrony – checking how big deviations are in the EEG signal
Although unsynchronised patterns of activity are also important e.g. some stages of sleep ae characterised by unsynchronised behaviour
what state of wakefullness/ sleep does this EEG depict?
an aroused (wakeful) state)
brain regions are not synchronised with eachother, observe only small deviations in EEG signal
what state of wakefullness/ sleep does this EEG depict?
relaxed but still wakeful state
what state of wakefullness/ sleep does this EEG depict?
asleep - beginning stages/ light sleep
what state of wakefullness/ sleep does this EEG depict?
asleep - deep sleep
large deviations observed as many neurons did the same thing simultaneously – large synchronisations occur and slower rate of change
what uni/ form of measurement are EEG signals measured in?
Expressed as the frequency of waves
What are wave frequencies?
The number of changes (how many times something happens) per second, measured in Hertz
What are hertz (Hz)?
The unit of frequency which measures how many times something happens per second.
1 hertz (hz) = one cycle/ per second
how many hertz (Hz) can be calculated from this image?
5 hz, because you can count five peaks or troughs per second
how many hertz (Hz) can be calculated from this image?
3 Hz , because you can count 3 peaks or troughs per second
EEG Wave Classifications from fastest to slowest - ask chatgpt to write MCQ questions about this flashcard to ensure you properly revised it
Fastest waves
• β: 13-30 Hz (per second) = beta waves
• α: 8-13 Hz alpha waves
• θ: 3.5-7.5 Hz theta waves
• δ: < 4Hz (under 4) = delta waves
Slowest waves
why are EEG waves classified differently?
there appears to be a qualitiative shift that occurs between these catagories
Each EEG wave category is functionally different based on frequency, origin and associated brain function (i.e. active / functioning during specific mental and physiological states e.g. delta waves dominant only in deep sleep and unconsciousness),
each category is somewhat synchronised within itself
