Dear all
I am wondering how to determine whether to use EEG, MEG, or fMRI and why their parameters on the spatial resolution and temporal resolution are hugely different. EEG has a high temporal resolution, and fMRI has a high spatial resolution. EEG has low sensitivity depth, and fMRI has high sensitivity depth. However, how is MEG? MEG has a high temporal resolution and a high spatial resolution, but it has low sensitivity depth. The spatial resolution and temporal resolution comparisons are below. These data are only obtained from some journals. In fact, the differences between these data are large.
EEG: spatial resolution (7-10 mm), temporal resolution (
One very practical aspect of replacing one of the methods you list with another is the type of study/experiment you plan. Though EEG and MEG may have similar spatio-temporal resolutions (at least if we are referring to extracranially recorded EEG), patients/probands assessed with MEG typically are not allowed to move, for most MEG measures are still made with SQUID sensors. Same constraint applies to fMRI. The main reason for the differences in spatio-temporal resolution between MEG/EEG and fMRI/PET is that the former record electrical signals, while the latter rely on changes in blood flow/blood oxygenation which is typically much slower than changes of electrical brain activity.
Roy Cox
Dear Dr Roy Cox
Thanks for your reply. I'm sorry I did not get my meaning across. In my third graph, the locations of the photos indicate the resolution. My purpose is to demonstrate that the data of the methods from the different sources indicate a different resolution.
Kaspar Anton Schindler
Dear Dr Kaspar Schindler
Thanks for your reply. I agree with your opinion that the deciding method shall depend on the study plan. I have the experience to analyse fMRI data, and I finished an EEG research. However, I followed my supervisors' suggestions on method usage. Now, I am researching hand perception. The topic was examined through three methods by my master supervisor. I am conceiving a new experiment relating to the issue. Thus, I must consider the benefits and drawbacks of these methods. Besides, although I have researched fMRI, I have never conducted an fMRI experiment personally. I did not notice an issue of experiment constraints to participants. Thanks for your note on basic physics. It helps me create a new experiment.
It is not all about resolution in time and space. Consider for example the sensitivity to source orientation, for example have a look at Article Sensitivity of MEG and EEG to source orientation
.Best
Simone Gastaldon
Dear Simone Gastaldon
Thanks for your reply. So far, I only have easy access to EEG. If I want access to other equipment, I must make a convincing proposal. As I reply to Kaspar Schindler, I am considering what aspect I want to explore regarding hand perception. I know how to use FieldTrip or SPM to analyse data, but I have poor knowledge of the brain. Thus, I am reinforcing the relevant knowledge. Besides, you mentioned a practical issue about using this equipment with respect to its price. I know that EEG is probably the easiest to access in many schools, including my school. However, when I write my report, I must verify the usage of EEG with an academic reason. I cannot say, ‘I use EEG because my school has no budget to buy MEG’. In any case, thank you for your heads up regarding the benefits and limitations of fMRI. It is beneficial for me in developing my current experiment. Additionally, thank you for your explanation on reconstructing the cortical source. I am planning to use a source localisation of EEG to rebuild the cortical source. It is a fascinating issue to me.
Renaud Marquis
Dear Renaud Marquis
Thanks for your reply. I am reading the interesting article that you suggested. I understand that the decision to use certain equipment is not all about spatial and temporal resolution. The article offers an excellent argument that MEG is not entirely better than EEG except for its high price and immovability of participants. The methods are available to complement each other's shortcomings. I am going to spend more time reading the article in detail.
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