What is brain mapping and how does it work? '. In this test a probe connected to a computer is attached to the person's head Through the medium of the computer the activity in the person's brain is recorded at the same time the doctor shows the picture of the object related to the test after that the activity in the person's brain recorded when the computer monitor the activity it generates five electrical waves such as Theta , Alpha., Beta , Delta , and high Beta this waves is generated only when the person think about the picture shown on the computer