MEG as an Enabling Tool in Neuroscience: Transcending Boundaries with New Analysis Methods and Devices

  • M. S. HämäläinenEmail author
  • D. Lundqvist
Reference work entry


Neuroscience studies have provided highly detailed information about the anatomical and structural composition and organization of the brain, but insights into its functional principles are still lacking. To advance this understanding, scientists need to match their new research questions with instruments that provide information about the brain’s functionality at a sufficient level of detail with a potential to resolve the very rapidly evolving patterns of brain activity while also providing the necessary spatial detail and accuracy. Until 50 years ago, electroencephalography (EEG) was the only noninvasive technique capable of directly measuring neuronal activity with a millisecond time resolution. However, with the birth of magnetoencephalography (MEG), functional brain activity can now be resolved with this time resolution at a new level of spatial detail.

The use of MEG in practical studies began with the first real-time measurements in the beginning of the 1970s. During the following decade, multichannel MEG systems were developed in parallel with both investigations of normal brain activity and clinical studies, especially in epileptic patients. The first whole-head MEG system with more than 100 channels was introduced in 1992. By the end of the century, hundreds of such instruments had been delivered to researchers and clinicians worldwide. With vibrant interaction between neuroscientists, clinicians, physicists, mathematicians, and engineers, the experimental approaches and analysis methods were developed to establish MEG as an important method to study healthy and diseased brains. With the advent of low-noise room-temperature magnetic field sensors and novel analysis approaches, we are now at the verge of a revolution that will critically improve both the sensitivity and the spatial resolution of MEG and will especially advance its use in studies of early brain development and neurodegenerative disorders, as well as investigations of brain function in naturalistic situations and during interpersonal interactions. This chapter focuses on instrumentation and analysis tool developments, which have enabled and continue to enable MEG to flourish as a noninvasive tool to study brain function. The final section of this chapter offers lessons learned from seasoned investigators on conducting successful MEG studies, necessarily emphasizing additional issues such as the formulation of the research question and creation of experimental protocols.


MEG EEG Source estimation MEG instruments Experimental design 


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Authors and Affiliations

  1. 1.Athinoula A. Martinos Center for Biomedical ImagingMassachusetts General HospitalCharlestownUSA
  2. 2.Harvard Medical SchoolBostonUSA
  3. 3.NatMEG, Department of Clinical NeuroscienceKarolinska InstitutetStockholmSweden

Section editors and affiliations

  • Seppo P. Ahlfors
    • 1
    • 2
  1. 1.Department of Radiology, MGH/HST Athinoula A. Martinos Center for Biomedical ImagingMassachusetts General HospitalCharlestown, MAUSA
  2. 2.Harvard-MIT Division of Health Sciences and TechnologyCambridgeUSA

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