Some thoughts on the interpretation of steady-state evoked potentials

Abstract

Steady-state evoked potentials are popular due to their easy analysis in frequency space and the availability of methods for objective response detection. However, the interpretation of steady-state responses can be challenging due to their origin as a sequence of responses to single stimuli. In the present paper, issues of signal extinction and some characteristics of higher harmonics are illustrated based on simple model data for those readers who do not regularly hobnob with frequency-space representations of data. It is important to realize that the absence of a steady-state response does not prove the lack of neural activity. For the same underlying reasons, namely constructive and destructive superposition of individual responses, comparisons of amplitudes between experimental conditions are prone to inaccuracies. Thus, before inferring physiology from steady-state responses, one should consider an alternative explanation in terms of signal composition.

Face-Evoked Steady-State Visual Potentials: Effects of Presentation Rate and Face Inversion

“…Heinrich (2010) purported that depending on repetition rate of the flickering stimulus, some components can be expected to be amplified and some to be eliminated by destructive interference. These processes would lead to differential sensitivity of the ssVEP to experimental manipulation as a function of what aspect of the transient evoked potential is retained, amplified, or eliminated.…”

“…Many aspects of the ssVEP can be modeled by linear superposition of single transient ERPs (Capilla et al, 2011). It is conceivable that such superposition may lead to destructive interference at certain frequencies, where components sensitive to face inversion are canceled out by interacting with previous or subsequent components overlapping in time (Heinrich, 2010). By the same token, other frequencies may be particularly beneficial in amplifying face inversion effects, where for instance the N170 of a previous flicker may superimpose on the subsequent N170 (constructive interference).…”

Steady-State Motion Visual Evoked Potentials Produced by Oscillating Newton's Rings: Implications for Brain-Computer Interfaces

“…Considering the hypothesis that steady-state responses can be explained by the temporal superposition of transient single-stimulus responses [15], [16], the destructive superposition of P1 and N2 components that were embedded in transient mVEPs elicited by individual motion reversals had great influence on the selection of motion reversal frequencies. For P1 latency of about 100 ms and N2 latency of 150–200 ms [5], [17], [18], a late N2 component evoked by former motion reversal may coincide with an early P1 component evoked by latter motion reversal when a specific motion reversal frequency was adopted and hence SSMVEPs disappeared.…”

“…For P1 latency of about 100 ms and N2 latency of 150–200 ms [5], [17], [18], a late N2 component evoked by former motion reversal may coincide with an early P1 component evoked by latter motion reversal when a specific motion reversal frequency was adopted and hence SSMVEPs disappeared. Further increase of motion reversal frequency would lead to destructive superposition of multiple N2 and P1 components that were evoked by a sequence of motion reversals and result in overall response decline within a wide frequency range [15]. Therefore, the inter-reversal interval of less than 50 ms would lead to decline or extinction of SSMVEPs to a great extent and the motion reversal frequency before 20 Hz was adopted in this paper.…”

A crossmodal crossover: Opposite effects of visual and auditory perceptual load on steady-state evoked potentials to irrelevant visual stimuli

“…SSEPs are cyclical oscillations of activity in sensory cortical areas evoked by a repeatedly presented or flickering stimulus stream (Di Russo et al, 2007;Heinrich, 2010;Picton et al, 2003;Toffanin et al, 2009;Vialatte et al, 2010). Such oscillations are evoked by both visual and auditory stimulation (e.g., Keitel et al, 2011;Saupe et al, 2009).…”