How the brain tissue shapes the electric field induced by transcranial magnetic stimulation (original) (raw)
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Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2010
Much of our knowledge about the electric field distribution in transcranial current stimulation (tCS) still relies on results obtained from layered spherical head models. In this work we created a high resolution finite element model of a human head by segmentation of MRI images, and paid particular attention to the representation of the cortical sheet. This model was then used to calculate the electric field induced by two electrodes: an anode placed above the left motor cortex, and a cathode placed over the right eyebrow. The results showed that the maxima of the current density appear located on localized hotspots in the bottom of sulci and not on the cortical surface as would be expected from spherical models. This also applies to the components of the current density normal and tangential to the cortical surface. These results show that such highly detailed head models are needed to correctly predict the effects of tCS on cortical neurons.
2015
This paper reviews the recently developed techniques in biomagnetics and bioimaging such as transcranial magnetic stimulation (TMS), magnetic resonance imaging (MRI), and cancer therapy based on magnetic stimulation. A technique of localized and vectorial TMS has enabled us to obtain non-invasive functional mapping of the human brain. The development of new bioimaging technologies such as current distribution MRI and conductivity MRI potentially enables us to understand the dynamics of brain functions, which include millisecond-level changes in functional regions and dynamic relations between brain neuronal networks. These techniques are leading medicine and biology into a new horizon through the novel applications of magnetism.