Brain Imaging
EIT has been suggested as a basis for brain imaging to enable the detection and monitoring of cerebral ischemia and haemorrhage, epileptic foci localization, together with research into normal brain function and neuronal activity.
In this use EIT depends upon applying low frequency currents above the skull that are around <100 Hz since during neuronal rest at this frequency these currents remain in the extracellular space unable enter into the intracellular space within neurons. However when a neuron makes an action potential or depolarization, the resistance of its membrane preventing this reduces by a factor of 80. When this happens across large numbers of neurons a resistivity change is made of about 0.06–1.7%. This resistivity change provides a means of detecting coherent neuronal activity across large numbers of neurons and so the tomographic imaging of neural activity in the brain.
Unfortunately while such changes are detectable "they are just too small to support reliable production of images." The prospects of using this technique for imaging will depend upon improved signal processing or recording.
Read more about this topic: Electrical Impedance Tomography
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