aEEG Glossary

Amplitude
A measurement of the level of brain activity detected as an electrical signal, measured in microvolts (µv) peak-to-peak.

Amplitude Integrated EEG (aEEG) 
A time-compression technique for presenting long EEG recordings, using an asymmetrical filter, peak rectifier and semi-logarithmic amplifier.

Artifact
Any electrical signal detected by an EEG machine from an extra-cerebral source (for example, electrode or cable movement, AC supply noise, ventilator noise).

Electrode
Conductor applied over, or inserted into, a region of the scalp or brain to detect electrical activity of the brain.

Frequency
The number of complete cycles of repetitive waves or complexes in one second, measured in Hertz (Hz).

Impedance
The opposition to the flow of an electric current through a conductor giving a measurement of the quality of contact between electrode and scalp.

Impedance values are determined by injecting a small constant current signal into each electrode and measuring the potential difference across the electrode-scalp interface (which is proportion to impedance, by Ohm's Law). Different frequencies are used for each sensor electrode.

International 10-20 System
Standardized electrode locations based on meridians crossing the scalp.

Odd numbers represent the left side of the brain.

Even numbers represent the right side of the brain.

Montage
The manner of arranging pairs of electrodes to produce channels of EEG information.

P/N 003096B