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. Author manuscript; available in PMC: 2020 Oct 1.
Published in final edited form as: Curr Opin Psychol. 2019 Jan 2;29:82–89. doi: 10.1016/j.copsyc.2018.12.016

Figure 1. Oscillatory entrainment and resonance.

Figure 1

EEG oscillator model response (black; [29]) relative to external sensory input (red) and concomitant band-pass filtered version (grey). Note that all 5 subpanels were derived from the same underlying oscillator model. (A) Evoked responses to rhythmic stimuli when no neural oscillator is present. Note that band-pass filtering renders the signal sinusoidal despite the absence of an ongoing oscillation. For an in-depth discussion of the relationship of evoked responses and phase-alignment see [25,26]. (B) No external sensory stream is present, but events are predicted based on top-down priors. Predicted events can either occur (green solid line) or not (green dashed line). However, the build-up of the ramping neural activity (such as contingent negative variation EEG potential, CNV) and subsequent return to baseline might mimic phase entrainment after band-pass filtering a linearly trending signal [29] due to filter-ringing. (C) True entrainment: An ongoing oscillator is entrained by a rhythmic input at a slightly different frequency. The entrained oscillation becomes phase-locked and the amplitude increases. After the entraining stream stops the oscillator exhibits a reverberation at the driving frequency for several cycles. (D) Resonating response to a single stimulus might mimic reverberations of a true oscillator. Note that band-pass filtering even renders the pre-stimulus period sinusoidal due to the single evoked response. Hence, phase estimates at stimulus onset might appear to be biased. However, phase estimates, after the initial evoked response, accurately track the phase of the decaying response. (E) Superposition of resonating responses to multiple stimuli mimics entrainment signatures as well as for phase-reset phenomena. Phase estimates after the initial response reflects a good approximation of the underlying signal. Note that neither this scenario nor panel A capture true, cognitively driven, phase alignment but mimic oscillatory patterns in response to a sensory stimulus.