Distribution of magnetic remanence carriers in the human brain

Abstract

That the human brain contains magnetite is well established; however, its spatial distribution in the brain has remained unknown. We present room temperature, remanent magnetization measurements on 822 specimens from seven dissected whole human brains in order to systematically map concentrations of magnetic remanence carriers. Median saturation remanent magnetizations from the cerebellum were approximately twice as high as those from the cerebral cortex in all seven cases (statistically significantly distinct, p = 0.016). Brain stems were over two times higher in magnetization on average than the cerebral cortex. The ventral (lowermost) horizontal layer of the cerebral cortex was consistently more magnetic than the average cerebral cortex in each of the seven studied cases. Although exceptions existed, the reproducible magnetization patterns lead us to conclude that magnetite is preferentially partitioned in the human brain, specifically in the cerebellum and brain stem.

Using the magnetoencephalogram to noninvasively measure magnetite in the living human brain

“…Considering the low resolution of our present method, in the older subjects we have seen that the magnetite could be in the upper brainstem (diencephalon and midbrain), the rostrally adjacent basal forebrain, or in the hippocampal formation; perhaps in any or all of those regions. This is in rough agreement with the findings in Gilder et al (), where the brainstem and surrounding regions contained the most magnetite. In our younger subjects, with less total mass, the locations are less certain.…”

“…These were found to have a range of sizes, from superparamagnetic to single domain (Bozorth, ; Jiles, ; Nagata, ). This first work was succeeded by further studies of magnetite in the normal brain (Kirschvink, Kobayashi‐Kirschvink, Diaz‐Ricci, & Kirschvink, ; Maher et al, ) including the distribution (Gilder et al, ) and effect of age (Dobson, ), and many studies of magnetite in brains with neurodegenerative disease (Castellani et al, ; Collingwood & Dobson, ; Collingwood & Telling, ; Dobson, , ; Grünblatt, Bartl, & Riederer, ; Hautot, Pankhurst, Khan, & Dobson, ; Pankhurst, Hautot, Khan, & Dobson, ; Plascencia‐Villa et al, ; Quintana et al, ; Scaiano, Monahan, & Renaud, ; Smith, Harris, Sayre, & Perry, ; Smith et al, ; Teller, Tahirbegi, Mir, Samitier, & Soriano, ).…”

Microbe‐Mediated Extracellular and Intracellular Mineralization: Environmental, Industrial, and Biotechnological Applications

“…[ 64 ] Magnetic remanence (residual magnetism) has been identified recently in the human body, particularly in the brain. [ 65 ] Magnetite is preferentially partitioned in the human brain, specifically in the cerebellum and brain stem. Biogenic remanent magnetite deposition in the human brain is similar to magnetite crystalline grown by MTB and is believed to be biologic precipitations as part of the body's iron metabolism.…”

Effects of Alzheimer’s disease and formalin fixation on the different mineralised-iron forms in the human brain

“…Moreover, magnetometry requires minimal sample preparation, contrary to TEM, thus lowering the risk of sample contamination. The observation that IRM curves obtained from human material saturate at magnetic fields of 300 mT or lower, and at temperatures between 50 K and 293 K 2,3,13,17,19,20 , and the occasional observation of the Verwey transition 3,19 , support the use of magnetometry techniques to detect and potentially quantify magnetite and/or oxidised magnetite, i.e. maghemite, nanoparticles in post-mortem or ex-vivo human samples.…”

“…While the most compelling evidence for the presence of magnetite in the human material has come from High Resolution Transmission Electron Microscopy (HRTEM) 1 and X-ray techniques 16 , magnetic analyses of Isothermal Remanent Magnetization (IRM) are often employed as complementary tools, or as a means of reporting concentrations of magnetite nanoparticles in the tissue 2,3,13,[17][18][19] . Although these latter measurements require very sensitive magnetometers, they offer the ability to study tissue blocks larger than those that can be studied by TEM, and the dimensions of such blocks are comparable to the spatial resolution of in vivo imaging techniques such as magnetic resonance imaging (MRI), meaning that magnetometry can potentially be employed to guide the interpretation of the contrast of, for example, magnetic susceptibility-weighted MRI images.…”