electroencephalography (EEG)

(noun)

Electroencephalography (EEG) is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. In clinical contexts, EEG refers to the recording of the brain's spontaneous electrical activity over a short period of time, usually 20 to 40 minutes, as recorded from multiple electrodes placed on the scalp. Diagnostic applications generally focus on the spectral content of EEG, that is, the type of neural oscillations that can be observed in EEG signals. In neurology, the main diagnostic application of EEG is in the case of epilepsy, as epileptic activity can create clear abnormalities on a standard EEG study. A secondary clinical use of EEG is in the diagnosis of coma, encephalopathies, and brain death.

Related Terms

Examples of electroencephalography (EEG) in the following topics:

  • Brain Imaging Techniques

    • Four of the most common types of brain scans are EEG, PET, MRI, and fMRI.
    • Electroencephalography (EEG) is used to show brain activity in certain psychological states, such as alertness or drowsiness.
    • To prepare for an EEG, electrodes are placed on the face and scalp.
    • Patients who suffer from epilepsy show an increase of the amplitude of firing visible on the EEG record.
    • To prepare for an EEG, electrodes are placed on the face and scalp.

  • Medical Imaging

    • Measurement and recording techniques which are not primarily designed to produce images, such as electroencephalography (EEG), magnetoencephalography (MEG), electrocardiography (EKG), but which produce data susceptible to be represented as maps (i.e. containing positional information), can be seen as forms of medical imaging.

  • Association Areas

    • Well-known techniques are EEG (electroencephalography), which records the brain's electrical activity, and fMRI (functional magnetic resonance imaging) , which tells us more about brain functions.

  • Stages of Sleep

    • In electroencephalography, the REM phase of sleep is easily identified by its paradigmatic fast, small-amplitude waves.
    • A sleep spindle is a burst of oscillatory brain activity visible on an EEG that occurs specifically during stage 2 sleep.
    • The criteria for REM sleep include rapid eye movements as well as a rapid low-voltage EEG.
    • During REM sleep, EEG patterns return to higher-frequency saw-tooth waves.
    • This sample hypnogram (EEG of sleep) shows how the proportion of the sleep cycle spent in REM sleep increases with each subsequent cycle over the course of a night.

  • Chance Processes

    • Familiar examples of processes modeled as stochastic time series include stock market and exchange rate fluctuations; signals such as speech, audio and video; medical data such as a patient's EKG, EEG, blood pressure or temperature; and random movement such as Brownian motion or random walks.
    • Familiar examples of processes modeled as stochastic time series include stock market and exchange rate fluctuations; signals such as speech, audio, and video; medical data such as a patient's EKG, EEG, blood pressure, or temperature; and random movement such as Brownian motion or random walks.

  • The Influence of Behavior on Genes

    • EEG and PET scans have the ability to show psychologists how certain behaviors trigger reactions in the brain.

  • The Symbolic Interactionist Perspective

    • Neurological evidence, based on EEGs, supports the idea that humans have a "social brain," meaning, there are components of the human brain that govern social interaction.

  • Describing Consciousness

    • Several brain-imaging techniques, such as EEG and fMRI scans, have been used for physical measures of brain activity in these studies.

  • A History of Theories of Consciousness

    • Several brain-imaging techniques, such as EEG and fMRI, have been used for physical measures of brain activity in these studies.

  • Neural Underpinnings of Consciousness

    • Researchers can record brain waves, or tracings of electrical activity within the brain, using an electroencephalograph (EEG) and placing electrodes on the scalp.