What does an EEG record?

An EEG, or electroencephalogram, records brain activity by measuring electrical activity along the scalp. This activity is represented as waves, which correspond to the rhythmic patterns of neural oscillations occurring in different regions of the brain. Each wave reflects different states of consciousness or cognitive processes, such as sleep, relaxation, and alertness.

The strength and frequency of these waves can provide valuable insights into how the brain functions during various activities or in response to different stimuli. For example, alpha waves typically indicate a person is relaxed yet alert, while delta waves are associated with deep sleep. This ability to represent brain activity in waveforms is what distinguishes the EEG from other methods of studying brain function.