This proposal documents our development of the neuromagnetic current probe from a crude and highly theoretical investigational device to a group of productive research instruments on the brink of clinical application. We propose a course of research that will enable us to continue to refine these techniques while applying them to test fundamental hypotheses in basic and clinical neuroscience. Since our first recordings of the magnetic field of an isolated nerve bundle in 1979, we have demonstrated the advantages offered by direct magnetic measurements of cellular action currents in vertebrate and invertebrate nerves. We have also developed mathematical models for analyzing the unique data obtained in these studies. In the course of developing models and improving the instruments for magnetic recording, we have identified specific applications for magnetic, techniques to address problems having significance for basic biomedical research and clinical medicine. Our past studies have provided us with a detailed understanding of the relationship between the electric and magnetic action signals of nerves. The unique properties of magnetic recording systems make them particularly practical for examining peripheral nerve injury, repair and regeneration in animal models and humans. We have developed a magnetic device that can be safely and effectively used in an operating room, and have developed a SQUID magnetometer having unprecedented resolution for use in our studies. Clinically-relevant studies include elucidating mechanisms of surgical tourniquet-induced nerve injury to determine means of prevention; assessing the effect of nerve compression in carpal tunnel syndrome, and aiding surgeons' selection of strategies to optimize repair of neuroma-in-continuity. Basic studies include characterization of action currents in single axons and peripheral nerve bundles in normal and injured states. We will exploit the magnetic current probes' non-traumatic scanning capability to examine axonal transport, impulse initiation, and the virtual cathode effect in squid giant axons, and to study neurotransmission at squid giant synapses. An implantable toroidal magnetic probe may afford longterm study of nerve regeneration. Completion of the proposed studies should provide new, basic information in neurophysiology, establish magnetic recording as a productive instrument for biomedical research and clinical application, and enhance the quality and safety of patient care.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
2R01NS019794-09
Application #
3399888
Study Section
Neurology A Study Section (NEUA)
Project Start
1987-03-01
Project End
1994-06-30
Budget Start
1991-07-15
Budget End
1992-06-30
Support Year
9
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Vanderbilt University Medical Center
Department
Type
Schools of Arts and Sciences
DUNS #
004413456
City
Nashville
State
TN
Country
United States
Zip Code
37212
Irimia, Andrei; Swinney, Kenneth R; Wikswo, John P (2009) Partial independence of bioelectric and biomagnetic fields and its implications for encephalography and cardiography. Phys Rev E Stat Nonlin Soft Matter Phys 79:051908
Kuypers, P D; van Egeraat, J M; van Briemen, L J et al. (1998) A magnetic evaluation of peripheral nerve regeneration: II. The signal amplitude in the distal segment in relation to functional recovery. Muscle Nerve 21:750-5
Kuypers, P D; van Egeraat, J M; Dudok v Heel, M et al. (1998) A magnetic evaluation of peripheral nerve regeneration: I. The discrepancy between magnetic and histologic data from the proximal segment. Muscle Nerve 21:739-49
Parker, K K; Wikswo Jr, J P (1997) A model of the magnetic fields created by single motor unit compound action potentials in skeletal muscle. IEEE Trans Biomed Eng 44:948-57
Kuypers, P D; van Egeraat, J M; Godschalk, M et al. (1995) Loss of viable neuronal units in the proximal stump as possible cause for poor function recovery following nerve reconstructions. Exp Neurol 132:77-81
van Egeraat, J M; Stasaski, R; Barach, J P et al. (1993) The biomagnetic signature of a crushed axon. A comparison of theory and experiment. Biophys J 64:1299-305
van Egeraat, J M; Wikswo Jr, J P (1993) A model for axonal propagation incorporating both radial and axial ionic transport. Biophys J 64:1287-98
Kuypers, P D; Gielen, F L; Wai, R T et al. (1993) A comparison of electric and magnetic compound action signals as quantitative assays of peripheral nerve regeneration. Muscle Nerve 16:634-41
Wijesinghe, R S (1991) A mathematical model for calculating the vector magnetic field of a single muscle fiber. Math Biosci 103:245-74
Gielen, F L; Friedman, R N; Wikswo Jr, J P (1991) In vivo magnetic and electric recordings from nerve bundles and single motor units in mammalian skeletal muscle. Correlations with muscle force. J Gen Physiol 98:1043-61

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