Time–Frequency Analysis of Event-Related Potentials: A Brief Tutorial

Abstract

Event-related potentials (ERPs) reflect cognitive processes and are usually analyzed in the so-called time domain. Additional information on cognitive functions can be assessed when analyzing ERPs in the frequency domain and treating them as event-related oscillations (EROs). This procedure results in frequency spectra but lacks information about the temporal dynamics of EROs. Here, we describe a method-called time-frequency analysis-that allows analyzing both the frequency of an ERO and its evolution over time. In a brief tutorial, the reader will learn how to use wavelet analysis in order to compute time-frequency transforms of ERP data. Basic steps as well as potential artifacts are described. Rather than in terms of formulas, descriptions are in textual form (written text) with numerous figures illustrating the topics. Recommendations on how to present frequency and time-frequency data in journal articles are provided. Finally, we briefly review studies that have applied time-frequency analysis to mismatch negativity paradigms. The deviant stimulus of such a paradigm evokes an ERO in the theta frequency band that is stronger than for the standard stimulus. Conversely, the standard stimulus evokes a stronger gamma-band response than does the deviant. This is interpreted in the context of the so-called match-and-utilization model.

Theta synchronization over occipito‐temporal cortices during visual perception of body parts

“…On the other hand, it has been suggested that ERPs are the results of a phase resetting of ongoing oscillatory activity, without changes of EEG power (Makeig et al ., ; see Sauseng et al ., for a review). It has also been suggested that both mechanisms may participate in the generation of ERP components (Herrmann et al ., ). Concerning early visual potentials (i.e.…”

Hemifield-dependent N1 and event-related theta/delta oscillations: An unbiased comparison of surface Laplacian and common EEG reference choices

“…While changes in neural oscillations are concealed by the ERP averaging process, a time-frequency decomposition of the single trials used to compute ERPs allows the quantification of event-related spectral changes over time (e.g., Makeig, 1993; Pfurtschneller and Lopes da Silva, 1999; Herrmann et al, 2014). To the extent that event-related oscillations contribute locally to the generation of N1pc, we hypothesize similar hemifield-dependent asymmetric EROs, presumably involving low frequencies in the theta and delta range, as previously observed for an auditory N1 (Kayser et al, 2014).…”

Stable Microsaccades and Microsaccade-Induced Global Alpha Band Phase Reset Across the Life Span

“…9 However, this phenomenon cannot be fully captured by averaged event related potentials (ERPs), which probe temporal-spatial dynamics of brain activities. 10 To overcome this limitation, we now applied time frequency analyses to characterize the microsaccade-related spectral power (event-related spectral perturbations [ERSPs]) and phase (intertrial coherence [ITC]). ERSPs measure the time course of relative changes in the spontaneous EEG amplitude spectrum induced by experimental events.…”