Electrophysiological correlates of gist perception: a steady-state visually evoked potentials study

[jinglescode]

Paper

Link: https://link.springer.com/article/10.1007/s00221-020-05819-6
Year: 2020

Summary

• multi-stimulus paradigms is suitable to measure brain activity related specifically to each stimulus separately
• two neighboring stimuli were flickered at different frequencies, SSVEPs enabled us to separate the responses to the two distinct stimuli by extracting oscillatory brain responses
• succeeded in eliciting oscillatory brain responses at the driving stimuli’s frequencies, their harmonics, and the intermodulation frequency, that is, f1 + f2 = 20.57 Hz
• brain’s response at a linear combination of two frequencies
• demonstrates that SSVEPs are an excellent method to unravel mechanisms underlying the processing within multi-stimulus displays in the context of gist perception
• multiple stimulus displays in combination with the analyses of intermodulation frequencies makes this an ideal approach to investigate gist perception in multi-stimulus processing

Methods

• 18 participants
• flicker frequencies of f1 = 8.57 Hz and f2 = 12 Hz (f2 is not a harmonic frequency of f1)

Results

• revealed clear and separable neuronal oscillations of two frequencies
• succeeded in eliciting oscillatory brain responses at the driving stimuli’s frequencies, their harmonics, and the intermodulation frequency, that is, f1 + f2 = 20.57 Hz
• occipital electrodes showed increased amplitudes at the intermodulation frequency
• In multi-stimulus SSVEP studies, intermodulation frequencies were found to be sensitive to visual integration and perceptual binding
• In a study by Gundlach and Müller (2013), two differently flickering stimuli were presented and the formation of an illusory rectangle occurred. The brain increasingly oscillated at the intermodulation frequency when the illusory figure was perceived compared to not perceiving it. Similarly, when moving bars are presented at two frequencies, intermodulation power was more increased during perceptual form or motion integration than during perceiving the stimuli as segmented components moving individually (Aissani et al. 2011).