Event-related Potential - ERP Components Nomenclature

ERP Components Nomenclature

ERP waveforms consist of a series of positive and negative voltage deflections, which are related to a set of underlying components' '. Though some ERP components are referred to with acronyms (e.g., contingent negative variation - CNV, error-related negativity - ERN, early left anterior negativity - ELAN, closure positive shift - CPS), most components are referred to by a letter (N/P) indicating polarity (negative/positive), followed by a number indicating either the latency in milliseconds or the component's ordinal position in the waveform. For instance, a negative-going peak that is the first substantial peak in the waveform and often occurs about 100 milliseconds after a stimulus is presented is often called the N100 (indicating its latency is 100 ms after the stimulus and that it is negative) or N1 (indicating that it is the first peak and is negative); it is often followed by a positive peak, usually called the P200 or P2. The stated latencies for ERP components are often quite variable. For example, the P300 component may exhibit a peak anywhere between 250ms - 700ms.

While evoked potentials reflect the processing of the physical stimulus, event-related potentials are caused by the "higher" processes, that might involve memory, expectation, attention, or changes in the mental state, among others.