(Greek: brain; that which is inside the head)
2. A partial or total absence of the brain at birth: "Doctor Darrin indicated that there are some babies who have been born with anencephalies at his hospital."
2. Convulsive equivalent, a form of epilepsy, especially in children.
2. A technique for studying the electrical currents within the brain.
Electrodes are attached to the scalp and wires attach these electrodes to a machine, which records the electrical impulses.
The results are either printed out or displayed on a computer screen where different patterns of electrical impulses can indicate various forms of epilepsy.3. A graphic record of the minute changes in electric potential associated with the activity of the cerebral cortex, as detected by electrodes applied to the surface of the scalp.
4. A graphic chart on which is traced the electric potential produced by the brain cells, as detected by electrodes placed on the scalp.
The resulting brain waves are called alpha, beta, delta, and theta rhythms; according to the frequencies they produce, which range from two to twelve cycles per second.
Variations in brain wave activity are correlated with neurological conditions, psychological states, and levels of consciousness.
2. An apparatus for receiving and recording the electric potential produced by the brain cells.
It consists of a vacuum tube amplifier that magnifies the electrical currents received through electrodes placed on the scalp and electromagnetically records the patterns on a graphic chart.3. An appliance that is used to amplify and to record the electrical activity of the brain, either through the intact skull and scalp, or directly from the exposed cerebral cortex (electrocorticography).
It is made up of a number of channels, each of which consists of an amplifying and recording instrument that records the electrical events beneath and between a pair of recording electrodes.