EEG- Measurement & Development

Question 1

How is EEG data practically used?

Answer 1

diagnostic marker of ADHD, medication effects, outcome measure for training studies, basis for all ERP studies, PPT

Question 2

What do EEGs measure?

Answer 2

Measure of brain electrical activity, recorded during resting states and active processing.

Measuring outcome of action potential: NTs bind to post-synaptic receptors -> headed IPSPs and EPSPs (measure from EEG)

Question 3

Where does rhythmical cortical EEG activity come from?

Answer 3

interaction between the thalamus and cortex

ARAS primary driver for cortical EEG

Question 4

Who described the first “brain wave”?

Answer 4

Caton (1875) in rabbits and monkeys- primarily slow wave activity (probably delta)

Question 5

Who described the first EEG activity in humans?

Answer 5

Berger (1929)- 2 basic wave patterns- large regular (alpha), smaller irregular (beta)

Question 6

Who later discovered delta and theta?

Answer 6

William Grey Walter- discovered delta waves during sleep and theta

Question 7

What are the characteristics of delta waves?

Answer 7

0.5-3.5Hz, 20-200uV, deep sleep, in very young children and in area of a lesion

Question 8

What are the characteristics of theta waves?

Answer 8

4-7Hz, 20-100uV, more frequent in children, indicator of maturational lag and general marker of patient dysfunction (if patient alert & awake)

Question 9

What are the characteristics of alpha waves?

Answer 9

8-12Hz, 20-60uV, relaxed waking state, eyes closed, mental inactivity, posterior dominant

Question 10

What are the characteristics of beta waves?

Answer 10

13-25Hz, 2-20uV, mental activity, frontocentral

Question 11

What are some less common waves?

Answer 11

Gamma- 30-120Hz? not heavily studied

Others: kappa, lambda, Mu

Question 12

Whats involved in a monopolar EEG recording?

Answer 12

Most frequently used. reference sit to compare active data against (usually on ear)

Question 13

Whats involved in a bipolar EEG recording?

Answer 13

Difference between 2 active electrodes (less frequently used)

Question 14

What is the international 10-20 system?

Answer 14

international convention that allows comparison of results- electrodes used in measurements between several point, with most placed at intervals of 10% or 20% of the distance
Electrode cap has distances built in
(also international 10-10 with more electrodes)

Question 15

What is spectral analysis?

Answer 15

Analysing the EEG- two ways:

1. Time Domain: amount of EEG activity within a time (Hz)
2. Frequency Domain: Amount of power within a given EEG frequency (uV)

Question 16

What is Fast Fourier Transform (FFT)?

Answer 16

Algorithm that analyses each waveform and quantifies amount of power within it.

Absolute power: measure of magnitude of the power in the EEG or a specific frequency band measured in uV2
Relative power: Amount of power that one frequency band contributes to entire power of EEG as a %
eg. relative theta = Absolute theta/ absolute (delta+theta+alpha+beta) x100

Question 17

What is co-modulation/is it effective?

Answer 17

Correlation between the power (frequency domain) at two electrode sites supposedly represents as measure of the fundamental connectivity between two regions -> not mainstream use as unproven procedure

Question 18

What is EEG coherence?

Answer 18

Better way of doing what co-modulation is trying to.
Correlation in time domain between 2 signals in a given frequency band (how similar is the shape of the brain waves at 2 electrode sites?)
High coherence indicates two locations functionally and/or structurally connected