Biomineralization of ferrimagnetic magnetite is known to occur in a number of organisms including animals [e.g. 1]. Recent investigations have revealed the presence of biogenic magnetite in human brain tissue as well [2,3,4]. The presence of magnetite in the brain has been established using a variety of magnetic and electron microscopic techniques.
The focus of this project - being conducted in co-operation with the Swiss Federal Institute of Technology (ETH-Zurich), the University Hospital Zurich, and the University of Hawaii - is on comparing and quantifying the amount of biogenic magnetite present in both normal and pathologic brain tissue samples in order to evaluate its possible role in diseases and disorders of the brain such as epilepsy. In order to accomplish this, methods were developed to quantify contamination levels and accurately measure tissue magnetite content .
In addition, we are examining tissue samples using scanning and transmission electron microscopy (SEM and TEM), electron energy loss spectroscopy (EELS) and energy filter TEM (EFTEM) imaging in order to locate the particles in the tissue and determine their relationships to structures in the brain.
The presence of ferrimagnetic material in human brain tissue also provides plausible theoretical mechanisms for the interaction of environmental magnetic fields with the human central nervous system [6,7]. These relationships are under investigation as well.
||Transmission electron micrographs of magnetite and/or maghemite particles extracted from a human hippocampus (96/624 - well defined crystal faces can be seen in some particles) and human hippocampus (96/624 - showing some particle dissolution at the edges).|
 Kirschvink, JL, DS Jones, BJ MacFadden (1985) Magnetite biomineralization and magnetoreception in organisms: a new biomagnetism. New York: R.P. Plenum Publishing Corp.
 Kirschvink, JL, A Kobayashi-Kirschivink, BJ Woodford (1992) Magnetite biomineralization in the human brain. Proc. Natl. Acad. Sci., USA, 89: 7683-7687.
 Dunn, JR, M Fuller, J Zoeger, JP Dobson, F Heller, E Caine and BM Moskowitz (1995) Magnetic material in the human hippocampus. Brain Res. Bull., 36: 149-153.
 Dobson, JP, M Fuller, S Moser, HG Wieser, JR Dunn and J Zoeger (1995) Evocation of epileptiform activity by weak D.C. magnetic fields and iron biomineralization in the human brain. In: Biomagnetism: Fundamental Research and Applications, eds. C Baumgartner, L Deecke, G Stroink, SJ Williamson. Elsevier, Amsterdam: 16-19.
 Dobson, JP and P Grassi (1996) Magnetic Properties of Human Hippocampal Tissue - Evaluation of Artefact and Contamination Sources. Brain Res. Bull., vol. 39: 255-259.
 Dobson, JP and T St. Pierre (1996) Application of the Ferromagnetic Transduction Model to D.C. and Pulsed Magnetic Fields: Effects on Epileptogenic Tissue and Implications for Cellular Phone Safety. Biochem. Biophys. Res. Comm., 227: 718-723.
 Kirschvink, JL (1996) Microwave absorption by magnetite: A possible mechanism for coupling of non-thermal levels of radiation to biological systems. Bioelectromag., 17: 187-194.
Prof. H.G. Wieser (University Hospital-Zurich), Paola Grassi (ETH-Zurich), Prof. M.D. Fuller (Univ. of Hawaii), Dr. Tim St.Pierre, (University of Western Australia), A.Prof. John Webb (Murdoch University), Wanida Chua-anusorn (Murdoch University).