EEG Fundamentals and Measurements

EEG (Electroencephalography)

• Records electrical activity from the brain
• Used to diagnose epilepsy and other brain disorders

EEG Recording

• Electrodes are placed on the head
• Records brain activity in different conditions
• Recording can be difficult due to interference from hair, scalp, and skull
• Proper connections and equipment are required

EEG Measurements

• Measures frequency (Hz: cycles per second) and amplitude (uV: microvolts)

Brain Wave Patterns

• Alpha Waves: 8-13 Hz, relaxed state with eyes closed
• Beta Waves: 13-30 Hz, alert state with eyes open
• Theta Waves: 4-8 Hz, young children and some sleep patterns
• Delta Waves: 1-4 Hz, deep sleep

Factors Affecting Brain Wave Activity

• Sensory stimuli
• Brain pathology: tumors, epilepsy, infections, stroke, dementia, head injury
• Changes in body chemistry: blood glucose, oxygen deprivation, drugs, blood pH
• Absence of any brain activity indicates death

Alpha Waves

• Measure the degree of cortical activity
• Alpha Block: interruption of alpha waves with stimuli (mental activity, vision, sound)
• More activity leads to less alpha wave activity

Long-Term (LT) EEG Recordings

• Focus on alpha pattern
• Electrodes placed on frontal and occipital areas
• Observe effects of muscle movement, mental concentration, sound, and vision on alpha waves
• Normal EEG amplitudes never exceed + or - 50 microV

EEG Frequency vs Amplitude

• Observe the relationship between frequency and amplitude

Lab Assignment

• Electroencephalography (EEG)
• Save report as a PDF and post in the MyCourses assignment box