Electroencephalograph

An electroencephalograph is the device used in electroencephalography to record an electrogram of the brain's own spontaneous electrical activity, most often abbreviated EEG. The signals it captures represent the combined postsynaptic potentials of pyramidal neurons in the brain's neocortex and allocortex, and the method is typically non-invasive, with electrodes placed on the scalp following the International 10-20 placement system to measure the resulting voltage fluctuations. Those readings let clinicians evaluate normal brain activity as well as detect abnormal electrical discharges such as seizure activity. The German psychiatrist Hans Berger is credited with the device's early development and named the first rhythmic EEG activity he observed the alpha wave, though the source consulted for this entry does not give a precise invention date, so none is recorded here.