Electroencephalography (EEG) is a non-invasive neuroimaging technique that measures the electrical activity of the brain. This method relies on the remarkable electrical communication that occurs within the brain's intricate network of neurons. Neurons, the fundamental building blocks of the nervous system, communicate by transmitting electrical impulses called action potentials. These electrical signals are generated when there is a change in the neuron's membrane potential due to the movement of ions across the cell membrane.

When neurons in the brain are active, they produce these action potentials in response to various stimuli and cognitive processes. In the cortex, this collective neuronal activity adds up and generates larger electrical fields. EEG electrodes, strategically placed on the scalp's surface, detect these electrical fields and record them as voltage fluctuations over time. These fluctuations give rise to the characteristic waveforms observed in EEG recordings, such as alpha waves during relaxed wakefulness, delta waves during deep sleep, or event-related potentials (ERPs) in response to specific sensory or cognitive events.

EEG's exceptional temporal resolution, capturing changes in electrical activity within milliseconds, makes it an invaluable tool for researchers studying the real-time dynamics of brain function. It is used to investigate a wide range of cognitive and neurological processes, including memory, attention, perception, and action control. With its ability to directly unveil the patterns in the brain's electrical activity, EEG continues to advance our understanding of the human brain and how it functions.