How Do EEG Machines Work?
The macroelectrodes attached to a subject’s scalp transmit electrical signals to the EEG machine, which acts as both an amplifier and as a galvanometer. The signals relayed to the EEG are typically amplified 10,000 times. Galvanometers are instruments that detect and measure small electric currents by means of a copper hoop or coil of wire that deflects a needle proportionate to the current flowing through the coil. The galvanometers are in turn hooked up to pens, which trace the electrical signals on graph paper moving continuously underneath them. EEGs allow researchers to record electrical impulses traveling across the surface of the brain and observe changes to those impulses. EEG recording have two useful features. First, they make continuous recording with split second accuracy. Second, EEGs can indicate the general conscious state of a person, e.g., asleep, awake, anaesthetized, since each state is correlated with particular EEG patterns. Thus, EEG recordings have been used meas
