Welcome to “Neuroscience Methods 101,” where we delve into the captivating world of magnetoencephalography (MEG). MEG is a sophisticated neuroimaging technique that complements electroencephalography (EEG) in studying brain activity patterns.
Similar to EEG, MEG measures brain signals generated by synchronized neuronal firing. However, MEG has a unique advantage: it detects magnetic fields instead of electrical signals. This distinction stems from Faraday’s law of induction, which states that an electrical current produces a magnetic field. Thus, MEG captures the magnetic fields generated by the electrical currents associated with neuronal activity.
The key difference between EEG and MEG lies in their sensitivity to brain signals. While EEG picks up signals from both surface convolutions (gyri) and grooves (sulci), MEG mainly registers signals from cortical sulci. Despite these variations, both techniques provide valuable insights into brain rhythms, such as alpha, beta, and gamma activity.
MEG offers exceptional spatial resolution because magnetic fields are unaffected by the skull and cerebrospinal fluid. This advantage enables researchers to pinpoint the brain areas responsible for recorded signals. In contrast, EEG signals are distorted by these factors, making precise localization challenging. The high cost and strict motion constraints of MEG are its drawbacks, but the superior spatial resolution often outweighs these limitations.