L10.5 - Techniques #2

Question 1

Time-frequency analysis plot

Answer 1

measures the multiple frequencies that make up EEG and MEG oscillations

Question 2

Event related potential (ERP)/ Event related field (ERF)

Answer 2

~ the activation elicited by a sensory stimulus

~ when you average out the oscillations, the background noise gets cancelled out

Question 3

Do EEG/MEG response directly reveal locus generation?

Answer 3

no as forward problem and inverse problem

Question 4

Forward problem

Answer 4

calculate field pattern when primary current known (easy)

Question 5

Inverse problem

Answer 5

calculate primary current from field pattern (hard)

Question 6

What are the solutions for the inverse and forward problem?

Answer 6

~ simplifying assumptions

~ constraining solutions using MRI or fMRI

Question 7

EEG and MEG pros

Answer 7

~ good temporal resolution
~ non-invasive
~ quiet good spatial resolution
~ can be combined with other techniques

Question 8

EEG and MEG cons

Answer 8

~ MEG sensitive to current orientation
~ MEG doesn’t see deep
~ localisation difficult and uncertain
~ EEG worse spatial resolution than MEG