Lecture 3 & 4: Electroencephalography (EEG) Questions With Solutions
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Course
Electroencephalography
Institution
Electroencephalography
Lecture 3 & 4: Electroencephalography
(EEG) Questions With Solutions
Why did Burger study medicine? Because he was convinced that there is "psychic
energy", which might allow for telepathy
He wanted to discover the objective activity in the brain and "psychic phenomena", but he did
not real...
Lecture 3 & 4: Electroencephalography
(EEG) Questions With Solutions
Why did Burger study medicine? Because he was convinced that there is "psychic
energy", which might allow for telepathy
He wanted to discover the objective activity in the brain and "psychic phenomena", but he did
not realise the basis and potential of his discovery at the time
What else did Burger describe? Alpha rhythm: characteristic frequency of electrical signal
when eyes closed
What is the characteristic frequency of alpha rhythm? 8-13 Hz
How did Burger measure electrical activity? Initially, he used two electrodes, one attached
to the front of the head and one to the rear, and recorded the potential (i.e. voltage) difference
between them.
Initially, electrodes were silver wires placed under the scalp
, Lecture 3 & 4: Electroencephalography
(EEG) Questions With Solutions
Later, sliver foil placed on the scalp
Advantage of EEG Great temporal resolution
Disadvantage of EEG Poor spatial resolution
In the electrode cap, on which side are odd numbers? Left side
In the electrode cap, on which side are even numbers? Right side
What does EEG activity reflect? The EEG activity does not reflect action potentials but
originates mostly from post-synaptic potentials - voltages that arise when neurotransmitters bind
to receptors on the membrane of the post-synaptic cell
This causes ion channels to open or close, leading to graded changes in the potential across the
membrane
, Lecture 3 & 4: Electroencephalography
(EEG) Questions With Solutions
What can these "graded changes" in potential across the membrane be understood as? A
small "dipole": signals from single cells are not strong enough to be recorded outside of the head,
but if many neurons spatially align, then their summed potentials add up and create the signals
we can record
Where does this pooled activity from groups of similarly oriented neurons come from?
Mostly comes from large cortical pyramid cells
Functional unit of simultaneously activated neurons for EEG >10,000 neurons
simultaneously activated
What determines the sign of the recorded potential (negative or positive)? The orientation
of the neurons
What happens if neurons are perpendicular to the scalp? NO Signal!
When can signals not be recorded? When the orientation of the neurons is not conducive
to a homogenous signal as measured by the scalp
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