There are many different types of neurons in the brain. Place cells, which are neurons in hippocampus, are involved in the planning of the route that the rats are going to perform [1]. The grid cells in rats participate in spatial localization via a triangulary coordination system in the endorhinal cortex. Such neurons have recently also been localized in human which indicate that we navigate by the same system [2]. For performing these tasks the cells must have a memory system. This iron oxide magnetite (Fe3O4) is the Earth's most important magnetic mineral. The human brain contains 5 million nanocrystals per gram tissue in the range of 10-70 nm, and some with 200 nm in diameter of this compound. In pia and dura mater (meninges) there are about 100 million crystals per gram [3]. These biogenic crystals in the brain are different from the geologically produced magnetite. They do not contain impurities like titanium and they have a different shape. In addition they appear to be oriented so as to maximize their magnetic moment which tends to give groups of these crystals the capacity to act as a system. It has been shown in pigeons that neurons can react on magnetic fields which indicate that it is a connection between memory and magnetism. It has been suggested that there is a link between magnetite in the neurons and storage of memory [4] and it has been described as membrane-bond occurring as crystalline in clusters or chains [5]. Every chemical reaction relies on quantum mechanics [6]. It gives the brain enormous storage capacity and speed and magnetite is a strong candidate to be involved in this process.
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