EEG PDF - Electroencephalogram

Electroencephalogram Lab 4 Miss Zaynab Yaseen Ahmed What is electroencephalogram (EEG)? An electroencephalogram (EEG) is a test that measures electrical activity in the brain using small, metal discs (electrodes) attached to the scalp. Brain cells communicate through...

Electroencephalogram Lab 4 Miss Zaynab Yaseen Ahmed What is electroencephalogram (EEG)? An electroencephalogram (EEG) is a test that measures electrical activity in the brain using small, metal discs (electrodes) attached to the scalp. Brain cells communicate through electrical impulses which are always active. This activity could be recorded through a series of waves in EEG. What Does the EEG Record? The Wave forms recorded by EEG reflect the activity of the surface of the brain and brain cortex. The electrical impulses of the brain will be sent via electrodes placed on the head to an amplifier and a series of waves will be recorded to be analyzed. How about the waves produced?  Delta: has a frequency of 3 Hz or below. It tends to be the highest in amplitude and the slowest waves. It is normal as the dominant rhythm in infants up to one year and in stages 3 and 4 of sleep. Theta: has a frequency of 3.5 to 7.5 Hz and is classified as "slow" activity. It is perfectly normal in children up to 13 years and in sleep but abnormal in awake adults. Alpha: has a frequency between 7.5 and 13 Hz. Is usually best seen in the posterior regions of the head on each side, being higher in amplitude on the dominant side. It appears when closing the eyes and relaxing and disappears when opening the eyes or alerting by any mechanism (thinking, calculating). It is the major rhythm seen in normal relaxed adults. It is present during most of life especially after the thirteenth year. Beta: beta activity is "fast" activity. It has a frequency of 14 and greater Hz. It is usually seen on both sides in symmetrical distribution and is most evident frontally. It is accentuated by sedative-hypnotic. It is generally regarded as a normal rhythm. It is the dominant rhythm in patients who are alert or anxious or have their eyes open. Why is an EEG performed? EEGs can check the status of brain- related conditions such as 1. epilepsy 2. Alzheimer’s disease or dementia. 3. Brain injury. 4. Infections including encephalitis. 5. Tumors. 6. Stroke. 7. Sleep disorders.