Electroencephalography (EEG) & Evoked Potentials Exam Questions and Answers 100% Pass

Electroencephalography (EEG) & Evoked Potentials Exam Questions and Answers 100% Pass 1. EEG defined a. The EEG is a measurement of ?. These voltage fluctuations are called? b. EEG recording: i. In humans, the electrodes are small metal disks pasted to the surface of the scalp by an electricity conducting gel. ii. There are two electrodes plugged into each amplifier on the EEG machine. The EEG recorder detects the voltage differences between the recording and reference electrode for each channel of detection. The amplifier compares the two electrode signals coming into it and cancels out signals that are the same. Therefore the EEG signal is the difference in ? iii. One electrode pair is referred to as a ?. Modern EEG recordings have from ? channels to produce a multichannel recording as shown here. 2Katelyn Whitman, All Rights Reserved © 2025 iv. The placement of the electrodes is important because the closer the electrodes are to each other the ?. If the electrodes are too close, the EEG channel will display a straight line. Therefore, when r - -voltage fluctuations at the surface of the scalp generated by the electrical activity of the brain - brain waves and are recordings of voltage difference versus time. -electrical activity detected by two electrodes. -channel -8 to 40 -less differences in their brain waves Figure 3: Standard placement of electrodes on a subject for multichannel EEG recording. Abbreviations: A, auricle; C, central; Cz, vertex; F, frontal; FP frontal pole; O, occipital; P, parietal; T, temporal. 3Katelyn Whitman, All Rights Reserved © 2025 i. The voltage emitted from the scalp is on the order of microvolts (10-6 volts). The EEG amplifiers increase this signal by a factor of several hundred thousand (105) for detection and recording. ii. Detected signals are either traced on strip chart paper or, more likely nowadays, are passed through an analog-to-digital processor and stored in digital format. iii. The digitized data can then be analyzed by Fourier transforms (FT) and filtering. FT is a mathematical way to ? Figure 4: Fourier transform of raw EEG data. Left, 5 different raw EEG channels of voltage vs time taken from 5 different electrodes. Right, Fourie