Event-related potentials (ERPs) are averaged scalp EEG responses time-locked to specific events in a sensory, motor, or cognitive task. The averaged responses or waveforms are composed of characteristic negative and positive deflections (i.e., components). They reflect the summated activity of network ensembles active during the various processes involved in the task (Luck, 2005). Time domain analysis compares the amplitudes and latencies of these sequential peaks and troughs. Early components with a latency of less than 100 milliseconds reflect sensory processes, followed by early components that are associated with attention processes, while later components reflect higher associative processes. See Figure 23.1 (top panel) for illustration of various ERP components. Most early studies used “oddball” paradigms and focused on the P3 or P300 component related to stimulus significance. Amplitude of P3 is taken to reflect central nervous system (CNS) inhibition (the larger the P3, the more the inhibition) (Birbaumer et al., 1990). While the P3 component, particularly in the oddball paradigm, is most widely used to study alcohol, more recent studies have focused on various other ERP components and cognitive tasks. This
