Electroencephalography (EEG) is a non-invasive technology that measures voltage fluctuations on the scalp that result from the synchronized activity of large groups of neurons in the brain. In some cases, this activity is associated with a particular stimulus or task. For instance, evoked potentials (Eps) and event-related potentials (ERPs) involve the time-locking of stimulus presentation (e.g. visual or auditory) to the measurement of scalp potentials. EEG has high temporal resolution (on the order of milliseconds), which gives it an advantage over other neuroimaging technologies such as fMRI and fNIRS. Because of its high temporal resolution, EEG activity can be correlated with specific stimulus events and behaviors at a very fine time scale. On the other hand, the spatial resolution of EEG is limited. To overcome this limitation, researchers at the University of Nevada, Reno, use a 256-channel high-density array EEG system. This system, combined with state-of-the-art neuroimaging software, allows the researchers to determine the source of EEG signals in the brain.