<human>:  How does the EEG work?
<bot>: The EEG is a device that measures the electrical activity of the brain. It is used to diagnose a variety of neurological conditions, and to monitor the brain during surgery. The EEG measures the electrical activity of the brain by placing electrodes on the scalp. The electrodes detect the electrical activity of the brain, and the device records the activity as a graph. The graph shows the electrical activity of the brain over time.