4.3 Physiology of EEG

Question 1

list 4 ways to measure electrical activity with electrodes in order from measuring the most specific brain activity (activity of individual neurons) to the least specific activity (activity of the brain as a whole)

Answer 1

1. intracellular recording
2. Single unit extracellular recording
3. Field potentials
4. EEG

Question 2

cortex, thalamus, midbrain, pons: which structures’ activity does EEG measure?

Answer 2

Electrodes are sensitive only to cells in cortex near the electrodes

Question 3

What is a large EEG signal indicate?

Answer 3

Large signals are the result of many neurons behaving in the same way, at the same time., i.e., synchronization of neural activity

Question 4

Why are multiple electrodes used to record the EEG?

Answer 4

they’re spread across the scalp evenly to measure the broadest area of activity possible in the cortex

Question 5

If your patient has 2-foot thick skull, how might that affect the EEG signal?

Answer 5

The signal is distorted and attenuated by tissue and bone.

Question 6

In what units are EEG potentials measured?

Answer 6

microvolt

Question 7

describe alpha-waves

Answer 7

moderate amplitude - typical of relaxed wakefulness.

They are typically recorded over the parietal and occipital lobules

Question 8

describe beta waves

Answer 8

Lower amplitude than alpha. are more commonly recorded over frontal areas and over other brain areas during intense mental activity

Question 9

describe Theta and delta waves

Answer 9

• found during drowsiness and early slow-wave sleep.

- Theta or delta waves present during wakefulness is a sign of brain dysfunction

Question 10

_____ _____ in EEG could be a seizure focus

Answer 10

sharp spikes in EEG could be a seizure focus.