“…Direct elemental mapping techniques include X-ray Fluorescence Microscopy (XFM), Proton Induced X-ray Emission (PIXE), Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), and Secondary Ion Mass Spectrometry (SIMS). These techniques (shown schematically in Figure 1), have enabled neuroscientists to directly study the distribution of Na + , K + , Mg 2+ , Ca 2+ , and Cl − , in situ within ex vivo tissue sections at cellular and sub-cellular spatial resolution, in conditions such as traumatic brain injury (Chwiej et al, 2011;Lozić et al, 2014), ischemic stroke (Caine et al, 2016;Pushie et al, 2018), hemorrhagic stroke (Hackett et al, 2015b;Williamson et al, 2016), schizophrenia (Lins et al, 2016), and epilepsy (Inamura et al, 1990;Ren et al, 1999;Chwiej et al, 2008;Chwiej et al, 2012a), to name a few (Figure 2). This mini-review highlights the recent applications of XFM, PIXE, LA-ICP-MS, and SIMS, to study the role of ions in healthy brain function and during disease or injury.…”