Advertisement

Magnetoencephalography in the Study of Human Brain Functions

  • Riitta Hari

Abstract

In magnetoencephalography (MEG), magnetic fields are measured with superconducting sensors outside the human head. The signals result mainly from intracellular currents that flow in synchronously active neurons of the fissurai cortex. Source and volume conductor models—like a current dipole within a sphere—are commonly used to determine locations of these currents. With multichannel SQUID magnetometers, field patterns can be constructed and source locations determined even with a “single shot” measurement without repositioning the instrument, opening new possibilities in clinical applications as well as studies of the neural basis of cognitive functions. Examples are given here of MEG recordings from auditory and somatosensory cortices.

Keywords

Median Nerve Auditory Cortex Somatosensory Cortex Noise Burst Current Dipole 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Ahonen A, Hämäläinen M, Kajola M, Knuutila J, Laine P, Lounasmaa OV, Simola J, Tesche C, Vilkman V (1992): A 122–channel magnetometer covering the whole head. In: Dittmar A, J Froment (eds) Proceedings of the Satellite Symposium on Neuroscience and Technology, 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. Lyon, France, November 1992, pp 16–20.Google Scholar
  2. Ahonen A, Hämäläinen M, Kajola M, Knuutila J, Lounasmaa OV, Simola J, Tesche C, Vilkman V (1991): Multichannel SQUID systems for brain research. IEEE Trans Magnet 27:2786–2792.CrossRefGoogle Scholar
  3. Galambos R, Makeig S, Talmachoff PJ (1981): A 40–Hz auditory potential recorded from the human scalp. Proc NY Acad Sci 78:2643–2647.CrossRefGoogle Scholar
  4. Hari R, Hämäläinen M, Joutsiniemi SL (1989): Neuromagnetic steady-state responses to auditory stimuli. J Acoust Soc Am 86:1033–1039.PubMedCrossRefGoogle Scholar
  5. Hari R, Hämäläinen H, Tiihonen J, Kekoni J, Sams M, Hämäläinen M (1990): Separate ringer representations at the human second somatosensory cortex. Neuroscience 37:245–249.PubMedCrossRefGoogle Scholar
  6. Hari R, Pelizzone M, Mäkelä JP, Hällström J, Leinonen L, Lounasamaa OV (1987): Neuromagnetic responses of the human auditory cortex to on- and off-sets of noise bursts. Audiology 25:31–43.CrossRefGoogle Scholar
  7. Hari R, Rif J, Tiihonen J, Sams M (1992): Neuromagnetic mismatch fields to single and paired tones. Electroenceph Clin Neurophysiol 82:152–154.PubMedCrossRefGoogle Scholar
  8. Huttunen J, Ahlfors S, Hari R (1992): Interaction of afferent impulses at the human primary sensorimotor cortex. Electroenceph Clin Neurophysiol 82:176–181.PubMedCrossRefGoogle Scholar
  9. Huttunen J, Hari R, Leinonen L (1987): Cerebral magnetic responses to stimulation of ulnar and median nerves. Electroencephalogr Clin Neurophysiol 66:391–400.PubMedCrossRefGoogle Scholar
  10. Karhu J, Hari R, Mäkelä JP, Huttunen J, Knuutila J (1992): Somatosensory evoked magnetic fields in multiple sclerosis Electroenceph Clin Neurophysiol 83:192–200.PubMedCrossRefGoogle Scholar
  11. Konishi M, Takahashi TT, Wagner H, Sullivan WE, Carr CE (1988): Neurophysiological and anatomical substrates of sound localization in the owl. In: Auditory Function. Neurobiological Bases of Hearing, Edelman GM, Gall WE, Cowan WM, eds., pp. 721–745. New York: Wiley.Google Scholar
  12. Loveless N, Hari R, Hämäläinen M, Tiihonen J (1989): Evoked responses of human auditory cortex may be enhanced by preceding stimuli. Electroencephalogr Clin Neurophysiol 74:217–227.PubMedCrossRefGoogle Scholar
  13. Mäkelä JP, Hari R, Valanne L, Ahonen A (1991): Auditory evoked magnetic fields after ischemic brain lesions. Ann Neurol 30:76–82.PubMedCrossRefGoogle Scholar
  14. Näätänen R, Picton T (1987): The N1 wave of the human electric and magnetic response to sound: A review and analysis of the component structure. Psychophysiology 24:375–425.PubMedCrossRefGoogle Scholar
  15. Pantev C, Hoke M, Lehnertz K, Lütkenhöner B, Anogianakis G, Wittkowski W (1988): Tonotopic organization of the human auditory cortex revealed by transient auditory evoked magnetic fields. Electroencephalogr Clin Neurophysiol 69:160–170.PubMedCrossRefGoogle Scholar
  16. Penfield W, Jasper H (1954): Epilepsy and the Functional Anatomy of the Human Brain. Boston: Little, Brown.Google Scholar
  17. Rif J, Hari R, Hämäläinen M, Sams M (1991): Auditory attention affects two different areas in the human auditory cortex. Electroencephalogr Clin Neurophysiol 79:464–472.PubMedCrossRefGoogle Scholar
  18. Romani GL, Williamson SJ, Kaufman L (1982): Tonotopic organization of the human auditory cortex. Science 216:1339–1340.PubMedCrossRefGoogle Scholar
  19. Sams M, Hari R, Rif J, Knuutila J (1993): The human auditory sensory memory trace persists about 10 s: Neuromagnetic evidence J Cogn Neuroscience 5:363–370.CrossRefGoogle Scholar
  20. Sams M, Aulanko R, Hämäläinen M, Hari R, Lounasmaa OV, Lu S, Simola J (1991a): Seeing speech: Visual information from lip movements modifies activity in the human auditory cortex. Neurosci Lett 127:141–145.PubMedCrossRefGoogle Scholar
  21. Sams M, Kaukoranta E, Hämäläinen M, Näätänen (1991b): Cortical activity elicited by changes in auditory stimuli: Different sources for the magnetic N100m and mismatch responses. Psychophysiology 28:21–28.PubMedCrossRefGoogle Scholar
  22. Tiihonen J, Hari R, Kajola M, Karhu J, Ahlfors S, Tissari S (1991): Magnetoencephalographic 10–Hz rhythm from the human auditory cortex. Neurosci Lett 129:303–305.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1994

Authors and Affiliations

  • Riitta Hari

There are no affiliations available

Personalised recommendations