Lecture 3 & 4: Electroencephalography (EEG) Questions And 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 () 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