Frontiers in Integrative Neuroscience Integrative Neuroscience

Abstract

Event-related potentials are characterized by an intricate series of components following the event or stimulus presentation. The components are thought to be generated by one or more generator sources or dipoles which are presumed to be located in cortical tissue that operate together and have specialized functions (Segalowitz and Davies, 2004). Components are believed to be associated with particular sensory or cognitive functions (Banaschewski and Brandeis, 2007) and are described by their topography, polarity, amplitude, and latency. The principal middle to late latency components of the ERP are a positive–negative–positive–negative complex typically labeled P1–N1–P2–N2 and begin around 40–50 ms and continue for another 150–250 ms (Polich, 1993; Ponton et al., 2000). A number of studies have found that the N1 and P2 have been found to be sensitive to intensity and frequency of auditory stimuli. Specifically, N1 and P2 amplitude increase with increasing intensity of auditory stimuli (e. In addition, N1 and P2 amplitudes are larger with lower frequency stimuli compared to higher frequency stimuli (Picton et al., 1974). Generally, ERP paradigms that are passive and do not require psychological action (i.e., evaluative or motor responses) often do not show deflections following the P2 or N2. However, in some situations, especially in an ERP elicited by a cognitive paradigm the N2 is followed by a pronounced positive peak, labeled P3 (or sometimes labeled P300, P3a, or P3b) and typically peaks around 250–450 ms, but the latency varies with the time required to process the event (Polich, 1993). While the early and middle latency sensory evoked potentials are often passive and involve no response or active cognitive processing by the participant, the later ERP components involve