文档介绍：ELECTROENCEPHALOGRAPHY
GJL, 2013
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OUTLINE
Step 1: definition, history, principle, electrode placement, pros and cons, clinical use
Step 2: EEG wave, types, rhythm, background activity
Step 3: abnomal EEG, factors
Step 4: EEG and disorders
Step 5:to be noted
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STEP 1
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DEFINITION
Electroencephalography is the recording of electrical activity along the scalp produced by the firing of neurons within the brain.
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HISTORY
1875 – Richard Caton from Jena, Germany discovered electrical brain activity by probing the surface of exposed brains of animals using a primitive version of the galvanometer.
1920’s – Hans Berger recorded human EEG with string galvanometers using subjects with holes in their skulls. He discovered waves at 10 Hz (named them Alpha waves because they were the first he isolated in the human EEG).
Dr. Hans Berger
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PRINCIPLE 1
The mechanism within neurons that creates action potentials through the exchange between sodium and potassium ions in and out of the cell
Adenosine Triphosphate (ATP) provides energy for proteins to pump 300 sodium ions per second out of the cell while simultaneously pumping 200 potassium ions per second into the cell (concentration gradient)
Thus making the outside of the cell more positively charged and the neuron negatively charged. This rapid ionic movement causes the release of action potentials
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PRINCIPLE 2
The structure and position of neurons (or brain cells) leads to the generation of an electrical potential
EEG has the ability to measure this electrical activity during normal and pathological states.
Obtaining EEG data consists of connecting bioelectric electrodes from the scalp (or exposed brain) into a machine capable of amplifying these microvolt (µv) signals so that they may be recorded on paper or recorded digitally.
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INTERNATIONAL 10-20 SYSTEM OF ELECTRODE PLACEMENT
Established in 1958
Electrodes are spaced at 10% or 20% of distances between specified anatomic landmarks
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