Lecture 3 & 4: Electroencephalography
(EEG) UPDATED ACTUAL Questions
and CORRECT Answers
What is Electroencephalography (EEG)? - CORRECT ANSWER - A method of detecting
neural activity by placing electrodes on the scalp
How does EEG work? - CORRECT ANSWER - Electrodes pick up small fluctuations of
electrical signals, originating from activity of (mostly cortical) neurons
Nature of electrical signals - CORRECT ANSWER - Very noisy and might not look like
much but systematically related to cognitive processes
How is EEG recorded? - CORRECT ANSWER - Either at the scalp (non-invasive) but
also possible to record
intra-cranial EEG by measuring activity directly at the exposed cortex
Logistics of EEG - CORRECT ANSWER - Cheap and (relatively) easy to conduct
Hans Berger (1873-1941) - CORRECT ANSWER - Detected the first EEG signal in 1924
with electrodes attached to the scalp of a human (his wife) and reported the results in 1929
Why did Burger study medicine? - CORRECT ANSWER - 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? - CORRECT ANSWER - Alpha rhythm: characteristic
frequency of electrical signal when eyes closed
, What is the characteristic frequency of alpha rhythm? - CORRECT ANSWER - 8-13 Hz
How did Burger measure electrical activity? - CORRECT ANSWER - 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
Later, sliver foil placed on the scalp
Advantage of EEG - CORRECT ANSWER - Great temporal resolution
Disadvantage of EEG - CORRECT ANSWER - Poor spatial resolution
In the electrode cap, on which side are odd numbers? - CORRECT ANSWER - Left side
In the electrode cap, on which side are even numbers? - CORRECT ANSWER - Right side
What does EEG activity reflect? - CORRECT ANSWER - 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
What can these "graded changes" in potential across the membrane be understood as? -
CORRECT ANSWER - 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
(EEG) UPDATED ACTUAL Questions
and CORRECT Answers
What is Electroencephalography (EEG)? - CORRECT ANSWER - A method of detecting
neural activity by placing electrodes on the scalp
How does EEG work? - CORRECT ANSWER - Electrodes pick up small fluctuations of
electrical signals, originating from activity of (mostly cortical) neurons
Nature of electrical signals - CORRECT ANSWER - Very noisy and might not look like
much but systematically related to cognitive processes
How is EEG recorded? - CORRECT ANSWER - Either at the scalp (non-invasive) but
also possible to record
intra-cranial EEG by measuring activity directly at the exposed cortex
Logistics of EEG - CORRECT ANSWER - Cheap and (relatively) easy to conduct
Hans Berger (1873-1941) - CORRECT ANSWER - Detected the first EEG signal in 1924
with electrodes attached to the scalp of a human (his wife) and reported the results in 1929
Why did Burger study medicine? - CORRECT ANSWER - 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? - CORRECT ANSWER - Alpha rhythm: characteristic
frequency of electrical signal when eyes closed
, What is the characteristic frequency of alpha rhythm? - CORRECT ANSWER - 8-13 Hz
How did Burger measure electrical activity? - CORRECT ANSWER - 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
Later, sliver foil placed on the scalp
Advantage of EEG - CORRECT ANSWER - Great temporal resolution
Disadvantage of EEG - CORRECT ANSWER - Poor spatial resolution
In the electrode cap, on which side are odd numbers? - CORRECT ANSWER - Left side
In the electrode cap, on which side are even numbers? - CORRECT ANSWER - Right side
What does EEG activity reflect? - CORRECT ANSWER - 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
What can these "graded changes" in potential across the membrane be understood as? -
CORRECT ANSWER - 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
