EEG PRACTICE EXAM QUESTIONS AND ANSWERS

What does the EEG measure? correct answer: EEG measures voltage fluctuations at surface of scalp = brain waves. What is a brain wave a measure of? correct answer: Change in Voltage over time (voltage vs. time) How is the EEG recorded? correct answer: Voltage difference between recording and reference electrodes Channel=one electrode pair 8-40 channels produce multichannel recording (modern EEG) What does the EEG signal measure? correct answer: Change in electrical activity detected by the 2 electrodes How should electrodes be placed? Why is this important? correct answer: Placement of electrodes: symmetrical and equidistant -the closer electrodes are to each other, the less difference in their brain waves -if electrodes placed too close, EEG channel displays a straight line What do EEG amplifiers do? correct answer: Voltage emitted by scalp on the order of microvolts -EEG amplifiers increase this signal 10^5 for detection and recording Once EEG recording is digitized, how is it analyzed? correct answer: Fourier Transform (FT): • Analyze wave data. • Converts voltage vs time to intensity vs frequency