EEG

Question 1

What does EEG measure?

Answer 1

Outcome of action potential. NT’s bind to post-synaptic receptors-> graded inhibitory post-synaptic potentials and excitatory post-synaptic potentials

EEG= sum of IPSPs and EPSPs in superficial layer

ARAS=primary driver

Question 2

Briefly explain the traditional EEG bands?

Answer 2

Delta: 0.5-3.5Hz, occurs in deep sleep, more common in very young children and area of lesion
Theta: 4-7, indicator of maturational lag and dysfunction
Alpha: 8-12, relaxed waking state or eyes closed
Beta: 13-25, mental activity, frontocentral

Question 3

What are two ways of recording EEGs and what is the international 10-20 system?

Answer 3

Monopolar: reference site to compare active data against
Bipolar: difference between two active electrodes

International 10-20: convention allowed comparison of results
Electrode placement based on measurements between several points, most placed at intervals of 10 or 20% of the distance (electrode cap is built in)

Question 4

What is Spectral analysis and Fast Fourier Transform?

Answer 4

EEG made up of activity of may diff freq bands- can be filtered to look at specific
2 ways: Time domain (amount of EEG within a time Hz), Frequency domain (amount of power within a given frequency uV)

FFT: algorithm analyses each waveform and quantifies amount of power within it
Absolute power: measure of magnitude of power in EEG or specific band uV
Relative power: amount of power that one frequency band contributes to entire power of EEG, %

Question 5

What is Co-Modulation and EEG Coherence?

Answer 5

Co-modulation: correlation between power at two electrode sites (supposedly) represents measure of functional connectivity between regions

EEG Coherence: does what ^ is trying to
Correlation in time domain between 2 signals of given frequency (how similar is shape of the brain waves at two electrode sites, similar= strong connectivity)

Question 6

What is EEG activation/Alpha blocking and does it relate to reaction time?

Answer 6

Change from dominant alpha to beta with stimulation or demand (open eyes, thinking, sound)
Lansing: faster RT when EEG blocking BEFORE vis stimulus (just increased arousal?) other studies didn’t find and relation

Question 7

What can effect hemispheric symmetry and is there differential activation during different tasks?

Answer 7

1. Power on one side greater than other
2. Change in frequency from resting to active greater on one side

Some behavioural studies suggest hemispheric specialisation eg. Left- language and maths but its ultimately a whole brain response

Question 8

What is EEG topography?

Answer 8

Variations in EEG across cortex “mapping” across surface- indicates relative increase or decrease

Delta, theta and alpha: posterior-> central and front (i.e back -> front)
Beta: central-> posterior-> frontal (spreading from centre)

Question 9

How does intelligence relate to EEG measures?

Answer 9

Argued to reflect “biological intelligence” free from culture - efficiency of brain functioning
Compare children to general pop or compare controls with clinical
Study: alpha udring fixation- less in gifted (similar to college students)