Fig. 3. A schematic illustration of the flash, pattern-reversal, and pattern onset-offset visual evoked potentials (VEPs) with their respective components. The flash VEP consists of a series of negative and positive deflections; the most prominent and reproducible of these peaks are the second negative peak (N2), with a normal latency of approximately 70 to 90 milliseconds, and the second positive peak (P2), with a normal latency of approximately 100 to 120 milliseconds. Pattern-reversal VEPs normally consist of three principal features: an initial negativity with a latency of approximately 70 to 80 milliseconds (N75), a larger positive component with a latency of approximately 90 to 110 milliseconds (P100), and a large negative component with a latency of approximately 130 to 140 milliseconds (N135). Typically, the pattern onset-offset VEP is characterized by three prominent components designated C1, C2, and C3 C1 is the initial positive component and has a latency of approximately 70 to 80 milliseconds. C2 is a large negative component and has a latency of approximately 100 to 120 milliseconds. C3 is the second major positive component and has a latency of approximately 140 to 150 milliseconds.