However, the central strength of magnetic resonance imaging is its excellent spatial resolution. fMRI has a tradeoff between spatial and temporal resolution, yet is a relatively slow neuroimaging method compared to methods such as EEG or MEG. The assumption is that neurons need more oxygen when they’re active. This excellent time resolution gives you insights on the precise timing of brain processing.įunctional Magnetic Resonance Imaging (fMRI):įMRI is a functional neuroimaging procedure measuring brain function by detecting changes in blood flow associated with neural activity. The changes in electric fields occur very fast – so with EEG, you will get insights into brain processes with a very high time resolution (up to 1 millisecond dependent on the sampling rate).ĮEG allows you to record brain processes that occur shortly after the onset of visual or audio stimuli (there are consistent brain processes already after 50-100 ms post-stimulus), but you can also monitor brain states reflecting engagement, motivation or drowsiness over longer periods (hours to days).
Keep in mind that EEG is a referential recording and not an absolute voltage – it always represents a relative increase or decrease in electricity at a specific location. The activity will be stronger compared to a reference location (typically located behind the ears referred to as the left/right “mastoid processes”). Because the electric fields are still very low, signals are generally amplified. Whenever large groups of these pyramidal cells are firing up in a synchronized pattern, the generated electricity radiates to the scalp surface – this is what we record with EEG electrodes. Specifically, electrical signals are picked up from gray matter regions, which have high densities of pyramidal cells that communicate with each other. When using EEG, you are measuring electrical activity generated by the various cortical layers of the human brain.
Of these methods, EEG is the most versatile and cost-efficient solution. The three most common and most frequently used measures are functional Magnetic Resonance Imaging (fMRI), magnetoencephalography (MEG) and electroencephalography (EEG). There are many different methods to go about capturing information on brain structures and functions.