<sod>electrodes on the scalp, it is possible to record the summed electrical activity of the cortex using a methodology known as [[electroencephalography]] (EEG).<ref>[[#refFisch|''Fisch and Spehlmann's EEG primer'']]</ref> EEG records average neuronal activity from the cerebral cortex and can detect changes in activity over large areas but with low sensitivity for sub-cortical activity. EEG recordings are sensitive enough to detect tiny electrical impulses lasting only a few milliseconds. Most EEG devices have good temporal resolution, but low spatial resolution.<eod>
<sod>===Electrodes and magnetic fields ===<eod>