Fig. 2: Audio-visual flicker induces a steady-state evoked potential in the human medial temporal lobe and prefrontal cortex. | Nature Communications

Fig. 2: Audio-visual flicker induces a steady-state evoked potential in the human medial temporal lobe and prefrontal cortex.

From: Multisensory flicker modulates widespread brain networks and reduces interictal epileptiform discharges

Fig. 2

A Example of 40 Hz-auditory (A) steady-state evoked potential (EP) in the hippocampus (HPC). (i) location of a depth electrode with contacts numbered from deep to superficial (zoomed-in below), in one subject, overlaid on pre-operative MRI; contacts 1–5 are in or near the hippocampus. (ii) Example local field potential (LFP) trace for the beginning of a 40Hz-A trial. (iii) For the same contact, averaged evoked potential over 2 cycles of the stimulus (left), averaged power spectral density (PSD) during 40Hz-A flicker (blue) and baseline (black, right). (iv) Averaged PSD for each contact from the depth electrode during 40Hz-A flicker, zoomed-in to show frequency of stimulation +/− 5 Hz (solid lines and shaded areas: mean +/− SEM), showing evoked responses in red contacts 3, 4, in the hippocampus, and weaker response in contacts 1, 6 and 7. B Same as (A), for a depth electrode in the superior prefrontal cortex (PFC) in a different subject, during 5.5 Hz-visual (V) flicker (orange). C Electrode contacts (dots) in the medial temporal lobe (MTL) and PFC that were modulated by 40 Hz-audiovisual (AV) flicker, on a MNI normalized brain (top view), with color representing fold-change in power at the frequency of stimulation, capped at 2-fold increase to best visualize this range (n = 793 contacts, 13 sessions, 13 subjects). Gray dots: contacts with no significant response. D Middle: fold-change in power (capped at 2-fold change) at 40 Hz during 40 Hz-AV flicker relative to baseline, for contacts with significant modulation; percent of electrodes showing significant steady-state EP above (n = 326 and 467 contacts, 13 sessions and subjects). Black open circles: medians, vertical lines: whisker plots, filled dots: each contact. 9 contacts had modulation higher than capped 2-fold change in the MTL, and 4 contacts in the PFC. Left and right: example power spectral densities during 40 Hz-AV flicker (green) or baseline (black) in the MTL and PFC, respectively. Lines and shaded areas: mean +/− SEM. Examples highlighted with red circles in the violin plots. Source data are provided as a Source Data file.

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