Magnetic analysis of human brain tissue.

Fourteen samples of human hippocampal tissue were resected during amygdalo-hippocampectomies performed on patients suffering from Mesial Temporal Lobe Epilepsy (MTLE). In addition, eight tissue samples from the hippocampus, cortex basalganglia, cerebellum and leptomeninges were resected from cadavers during routine autopsy and were not chemically fixed. All samples were preserved in liquid nitrogen and magnetic properties were measured at 77K and 273K. Measurements indicate that there are no systematic variations in magnetic particle concentrations or magnetic properties between MTLE patients and non-pathologic tissue from the cadavers. The presence of superparamagnetic particles can be inferred due to differences in the saturation remanence acquired at 77K and 273K. This is a further indication that biogenic magnetite and/or maghemite present in the human brain likely is not primarily associated with geomagnetic field sensing as it is known to occur in other organisms.