Electroencephalography is the neurophysiological measurement of electrical activity in the brain as recorded by electrodes placed on the scalp or, in special cases, subdurally or in the cerebral cortex. The resulting traces are known as an electroencephalogram (EEG) and represent a summation of post-synaptic potentials from a large number of neurons.
The use of EEG in neuroscience research delivers a number of benefits. One is that EEG is non-invasive for the research subject. Furthermore, the need to restrict the subject‘s movements is clearly lower than in other fields of neuroscience such as functional magnetic resonance imaging (fMRI). A further benefit is that many EEG applications record spontaneous brain activity, which means that the subject does not need to be able to cooperate with the researcher (as is necessary, for instance, during behavioral testing in neuropsychology). Also, EEGs have a high temporal resolution compared with techniques such as fMRI and PET and are capable of detecting changes in electrical activity in the brain on a time scale in the millisecond region.