New imaging method maps the brain's electrical conductivity

It will allow anaesthetists a moment-by-moment account of patients undergoing major surgery or for close monitoring of trauma, such as head injury or stroke.

Temporal brain scanning, which can see how the brain reacts to various stimuli, already exists in the form of functional magnetic resonance imaging (fMRI). This technology works by tracking changes in blood flow that are indicative of underlying neural activity. Yet because it based on the principle that active neurons demand oxygen, there is a natural lag in the time it takes blood flow to respond.

By contrast, the new imaging method — called functional electrical impedance tomography of evoked response (fEITER) — is based on rapid electrical activity deep in the brain.  

The machine itself is a portable, lightweight monitor that can fit on a small trolley. It has 32 electrodes that are fitted around the patient’s head. A small, high-frequency electric current, too small to be felt or have any effect, is passed between two of the electrodes and the voltages between other pairs of electrodes are measured, in a process that takes less than one-thousandth of a second.