Non-evoked frequencies: Retinotopic position modulation induces SSVEP signals without intrinsic neural signal processing

Abstract

AbstractSteady-state visually evoked potentials (SSVEPs) are defined as periodic EEG responses elicited by periodic modulations in visual stimuli. These periodic responses can be extracted as narrowband frequency components by employing frequency domain analyses. Frequency components extracted this way are traditionally attributed to modulations in neuronal activity, particularly of neurons sensitive to a modulated stimulus property. Here, we demonstrate a scenario in which frequency components arise solely due to retinotopic variations in signal strength without representing the activity of any specific neural mechanism. Specifically, we present evidence from two EEG experiments for the existence of signal fluctuations that depend solely on retinotopic stimulus position, which are also able to yield identifiable frequency components in the face of a position-modulated stimulus. Given the large extent of positional variation in our stimulus, these position-dependent fluctuations likely reflect the factors that impact the strength of the measured responses from different retinotopic areas. These results offer a counterexample to the conventional approach of associating frequency components with neuronal activity, and underscore potentially confounding interactions between stimuli and the brain’s architecture.