BIOL 251: 4 Types of Brain Waves

Electroencephalograms (EEGs)

machines that can measure electrical activity of the brain by measuring the electrical potential differences between different areas of the cerebral cortex.

When there are no brain waves on an EEG, it is called a flat EEG and is one of the clinical signs of death. 

Alpha waves

measured when the subject is conscious (awake) but relaxed with their eyes closed.

alpha block

If the subject opens their eyes or begins to focus or concentrate on a problem, the waves decrease in amplitude but increase in frequency.

Beta waves

similar to alpha waves but with lower amplitude and higher frequency.

Beta waves are measured when the subject is mentally alert or concentrating on a problem or visual stimulus.

Theta waves

n irregular wave pattern that is typically observed in children.

They are uncommon in conscious adults but may sometimes appear if someone is concentrating.

delta waves

observed in young children and infants when they are relaxed or sleeping. These are the slowest waves recorded in humans.