A Method for Tracking the Time Evolution of Steady-State Evoked Potentials

Abstract

Neural entrainment refers to the synchronization of neural activity to the periodicity of sensory stimuli. This synchronization defines the generation of steady-state evoked responses (i.e., oscillations in the electroencephalogram phase-locked to the driving stimuli). The classic interpretation of the amplitude of the steady-state evoked responses assumes a stereotypical time-invariant neural response plus random background fluctuations, such that averaging over repeated presentations of the stimulus recovers the stereotypical response. This approach ignores the dynamics of the steady-state, as in the case of the adaptation elicited by prolonged exposures to the stimulus. To analyze the dynamics of steady-state responses, it can be assumed that the time evolution of the response amplitude is the same in different stimulation runs separated by sufficiently long breaks. Based on this assumption, a method to characterize the time evolution of steady-state responses is presented. A sufficiently large number of recordings are acquired in response to the same experimental condition. Experimental runs (recordings) are column-wise averaged (i.e., runs are averaged but epoch within recordings are not averaged with the preceding segments). The columnwise averaging allows analysis of steady-state responses in recordings with remarkably high signal-to-noise ratios. Therefore, the averaged signal provides an accurate representation of the time evolution of the steady-state response, which can be analyzed in both the time and frequency domains. In this study, a detailed description of the method is provided, using steady-state visually evoked potentials as an example of a response. Advantages and caveats are evaluated based on a comparison with single-trial methods designed to analyze neural entrainment.

Persistence of EEG Alpha Entrainment Depends on Stimulus Phase at Offset

“…The duration of the trials varied between 4.5 and 5 s, depending on the IAF of the participant and the experimental condition (phase of the stimulation at the offset). To avoid adaptation, the trials were followed by a resting interval of 2 s (Prado-Gutiérrez et al, 2019). Each block lasted between 6.5 and 7 min, with 1 min of rest in between.…”

“…Forty-five trials belonging to the same experimental condition were time-domain averaged to increase the SNR of the measurements (Figure 2A). As a result, the SSVEP signals used for further analysis represented phase-locked brain oscillations across trials (Labecki et al, 2016;Prado-Gutiérrez et al, 2019).…”

Visual Evoked Potentials as Potential Biomarkers of Visual Function in Patients with Primary Sjögren’s Syndrome

“…The evoked potential examination was conducted using the Viking Quest equipment. The procedure was conducted according to the International Federation of Clinical Neurophysiology (IFCN) and American Society of Electroencephalography [ 18 , 19 ] guidelines. The evoked potentials were recorded at a fixed time (after breakfast, before noon).…”

Predicting sensorimotor responses to rhythmic events : an EEG study of neuronal entrainment & beat perception (cognizant through harmonics)

“…This study is based on the understanding that stimuli, either visual or auditory, presented constantly at a frequency will evoke brain responses mirroring those exact periodicities of the given stimuli. These constant periodic responses are termed Steady State Evoked Potential (SS-EPs), which showcases the phenomenon of neural entrainment (Prado-Gutiérrez, et al, 2019).…”