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Magnetoencephalography
  1. Malcolm Proudfoot1,2,
  2. Mark W Woolrich2,
  3. Anna C Nobre2,
  4. Martin R Turner1
  1. 1Nuffield Department of Clinical Neurosciences, University of Oxford, UK
  2. 2Oxford Centre for Human Brain Activity, University of Oxford, UK
  1. Correspondence to Dr Martin Turner, Nuffield Department of Clinical Neurosciences, West Wing Level 3, John Radcliffe Hospital, Oxford OX3 9DU, UK; martin.turner{at}ndcn.ox.ac.uk

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Introduction

The understanding of brain function is moving rapidly towards a systems-level, network-based approach. It is now as naive to talk simplistically about what a particular area of the brain ‘does’, as it was for Franz Joseph Gall (1758–1828) to link its performance to the thickness of the overlying skull. Magnetoencephalography (MEG) is a rapidly developing and unique tool for the study of brain function, in particular the underlying oscillations in neuronal activity that appear to be fundamental (box 1), with real-time resolution and potential for application across a range of brain disorders. We provide a brief overview of the technology, broad approaches to data analysis, and aspirations for its application to the study of neurodegeneration.

Box 1

An introduction to neuronal oscillations

  • Neuronal oscillatory activity is continuous, but fluctuations in power and timing allow rapid alteration in communication strength within existing structural network architecture, far faster than synaptic modification.1

  • Two distinct cerebral regions can facilitate preferential information exchange by synchronising their rhythmic behaviour; the γ band (40–80 Hz), in particular, facilitates this process, but is also modulated ‘top-down’ by lower frequencies such as θ (4–7 Hz), reflecting factors, such as arousal states.

  • α Rhythms (8–13 Hz), so prominent in the occipital cortex upon eye closure, reflect more than just an ‘idling’ rhythm but also contribute to active allocation of attentional resources and suppress irrelevant sensory information.2

  • The influential theory ‘Communication through Coherence’ developed by Fries,3 builds on existing models of ‘binding by synchronisation’ that may underpin selective attention, a key function in prioritising neural events to guide awareness and action.4

Functional brain imaging so far

Structural MR imaging of the brain and spinal cord has revolutionised the accuracy of diagnosis in common conditions, such as stroke, and greatly expanded the taxonomy of neurological disorders. Advanced applications of MRI now allow the assessment of white …

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