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Functional localization based on measurements with a whole-head magnetometer system

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Summary

Whole-cortex magnetometers represent a significant methodological breakthrough in noninvasive studies of the brain's electrical activity. This paper describes our 122-channel instrument with planar gradiometers, methods to interpret its data, and gives a few examples of neuromagnetic studies.

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References

  • Ahonen, A.I., Hämäläinen, M.S., Kajola, M.J., Knuutila, J.E.T., Laine, P.P., Lounasmaa, O.V., Parkkonen, L.T., Simola, J.T. and Tesche, C.D. 122-channel SQUID instrument for investigating the magnetic signals from the human brain. Physica Scripta, 1993a, T49: 198–205.

    Google Scholar 

  • Ahonen, A.I., Hämäläinen, M.S., Ilmoniemi, R.J., Kajola, M.J., Knuutila, J.E.T., Simola, J.T. and Vilkman, V.A. Sampling theory for neuromagnetic detector arrays. IEEE. Trans. Biomed. Eng., 1993b, 40: 859–869.

    PubMed  Google Scholar 

  • Forss, N., Hari, R., Salmelin, R., Ahonen, A., Hämäläinen, M., Kajola, M., Knuutila, J. and Simola, J. Activation of the human posterior parietal cortex by median nerve stimulation. Exp. Brain Res., 1994, 99: 309–315.

    PubMed  Google Scholar 

  • Golub, G.H. and van Loan, C.F. Matrix computations, 2nd Ed. The Johns Hopkins University, Baltimore, 1989.

    Google Scholar 

  • Hämäläinen, M.S. and Sarvas, J. Realistic conductivity geometry model of the human head for interpretation of neuromagnetic data. IEEE Trans. Biomed. Eng., 1989, 36: 165–171.

    PubMed  Google Scholar 

  • Hari, R., Ahonen, A., Forss, N., Granström, M.-L., Hämäläinen, M., Kajola, M., Knuutila, J., Lounasmaa, O.V., Mäkelä, J.P., Paetau, R., Salmelin, R. and Simola, J. Parietal epileptic mirror focus detected with a whole-head neuromagnetometer. NeuroReport, 1993, 5: 45–48.

    PubMed  Google Scholar 

  • Mosher, J.C., Lewis, P.S. and Leahy, R. Multiple dipole modeling and localization from spatio-temporal MEG data. IEEE Trans. Biomed. Eng., 1992, 39: 541–557.

    PubMed  Google Scholar 

  • Salmelin, R., Hari, R., Lounasmaa, O.V. and Sams M. Dynamics of brain activation during picture naming. Nature, 1994, 368: 463–465.

    PubMed  Google Scholar 

  • Scherg, M. Fundamentals of dipole source potential analysis. In: F. Grandori, M. Hoke and G.L. Romani (Eds.), Auditory Evoked Magnetic Fields and Electric Potentials. Adv. Audiol., Vol. 6., Basel, Karger, 1990: 40–69.

    Google Scholar 

  • Seppä, H., Ahonen, A., Knuutila, J., Simola, J. and Vilkman, V. Dc-SQUID electronics based on adaptive positive feedback: Experiments. IEEE Trans. Magn., 1991, 27: 2488–2490.

    Google Scholar 

  • Uusitalo, M.A., Ilmoniemi, R.J. and Tesche, C.D. The signal-space projection (SSP) method. International Society for Brain Electromagnetic Topography. 5th International congress, 1995, Vol 7(4): 340.

    Google Scholar 

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This paper describes work which is undertaken in our laboratory in a multidisciplinary team lead by Professors Olli V. Lounasmaa and Riitta Hari. I am grateful to Riitta Salmelin and Olli V. Lounasmaa for comments on this manuscript.

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Hämäläinen, M.S. Functional localization based on measurements with a whole-head magnetometer system. Brain Topogr 7, 283–289 (1995). https://doi.org/10.1007/BF01195254

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