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.
2. A method of graphically recording the electric activities of the brain, particularly the cerebral cortex, with electrodes attached to the scalp.
This process is used in the diagnosis of epilepsy, trauma, tumors, and degenerations of the brain; as well as, in the study of the effects of drugs on the central nervous system and certain psychological and physiological functions.
Electrodes are placed on the scalp in various locations and the difference between the electric potential of two sites is recorded. The difference between one pair or among many pairs at a time can be determined.
The use of this diagnostic technique has proven to be very helpful in studying epilepsy and convulsive disorders and in localizing lesions in the cerebrum.
During the procedure, the patient must remain quiet, with eyes closed, and not talk or move.
In certain cases prescribed activities; especially, hyperventilation, may be requested by the technician.
The test is used to diagnose seizure disorders, brainstem disorders, focal lesions, and impaired consciousness.
During neurosurgery, the electrodes can be applied directly to the surface of the brain (intracranial electroencephalography) or placed within the brain tissue (depth electroencephalography) in order to detect any lesions or tumors that might exist.