Magnetic field tomography of coherent thalamocortical 40-Hz oscillations in humans

U. Ribary, A. A. Ioannides, K. D. Singh, R. Hasson, J. P.R. Bolton, F. Lado, A. Mogilner, R. Llinás

Research output: Contribution to journalArticlepeer-review

454 Scopus citations


This paper introduces the use of magnetic field tomography (MFT), a noninvasive technique based on distributed source analysis of magnetoencephalography data, which makes possible the three-dimensional reconstruction of dynamic brain activity in humans. MFT has a temporal resolution better than 1 msec and a spatial accuracy of 2-5 mm at the cortical level, which deteriorates to 1-3 cm at depths of 6 cm or more. MFT is used here to visualize the origin of a spatiotemporally organized pattern of coherent 40-Hz electrical activity. This coherence, initially observed during auditory input, was proposed to be generated by recurrent corticothalamic oscillation. In support of this hypothesis, we illustrate well-defined 40-Hz coherence between cortical-subcortical sites with a time shift that is consistent with thalamocortical conduction times. Studies on Alzheimer patients indicate that, while a similar activity pattern is present, the cortical component is reduced in these subjects.

Original languageEnglish (US)
Pages (from-to)11037-11041
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number24
StatePublished - 1991
Externally publishedYes


  • Alzheimer disease
  • Auditory activity
  • Cognition
  • Magnetic resonance imaging

ASJC Scopus subject areas

  • General


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