Effects of Neuronic Shutter Observed in the EEG Alpha Rhythm

Example of the staircase method used to determine the threshold intensity in a single participant. Each time the participant observed the stimulus, the intensity in the next trial was decreased. If the participant did not observe the stimulus in one trial, the intensity was increased in the next trial. Threshold intensity was determined as the average intensity of all trials (trials 6–40 in this example) following the third reversal, or corner, in the trial-intensity trace (trial 5 in this example). The dashed threshold intensity line in this figure spans the trials over which the intensities were averaged.

Each of the 20 participants’ α peak-to-peak amplitude distribution for all trials used in the analysis at t2.

C1 VEP component averaged across all participants in response to upper and lower visual field stimuli. The difference waveform is the lower waveform subtracted from the upper waveform. The mean and range of each participant’s estimated retina-to-V1 conduction delay (t2) is indicated and was calculated as the peak latency of the C1 component in each individual’s difference waveform.

Mean change in OR (ΔOR) for each amplitude and phase condition relative to mean OR across all conditions when analysis was conducted at t2 (error bars indicate standard error). Tukey’s HSD tests were performed between phase levels within amplitude conditions with significance indicated by *. Bonferroni corrected t tests compared each mean to zero with significance indicated by #; 90° = peak; *,#p ≤ 0.05; **,##p ≤ 0.01; ***,###p ≤ 0.001; ****,####p ≤ 0.0001.

ΔOR as a function of phase for each participant in the high-amplitude and low-amplitude conditions with radial axis extending to negative values for analysis conducted at t2. The preferred phase is indicated on the circumference, calculated as the direction toward the circle’s center of mass; 90° = peak.

Analysis conducted at t2. A, C, ΔOR as a function of phase, with radial axis extending to negative values. B, D, Individual participants’ preferred phase angles; their magnitude is proportional their individual PPE. The width and height of the shaded rectangles indicate, respectively, the x and y 95% CI in cartesian space. In all panels, the group mean preferred phase is indicated in black on the circumference of the diagrams, with the shaded region indicating estimated 95% CIs for each amplitude condition; 90° = peak.

Change in α amplitude, relative to a −300 to −100 ms baseline interval (A), and α phase coherence for observed, missed, and all stimuli together (B). The arrow indicates a peak in the missed trial phase coherence reflecting the time point were α phase best predicts that a trial will be unobserved by the participant. There was no indication of stimulus-induced effects at the t2 time point where phase and amplitude measures were hypothesized to be of mechanistic relevance.

Analysis conducted at t = −100 ms. A, C, ΔOR as a function of phase, with radial axis extending to negative values. B, D, Individual participants’ preferred phase angles; their magnitude is proportional their individual PPE. The width and height of the shaded rectangles indicate, respectively, the x and y 95% CI in cartesian space. In all panels, the group mean preferred phase is indicated in black on the circumference of the diagrams, with the shaded region indicating estimated 95% CIs for each amplitude condition; 90° = peak.

Mean change in OR (ΔOR) for each amplitude and phase condition relative to mean OR across all conditions when analysis was conducted at t = −100 ms (error bars indicate standard error). Tukey’s HSD tests were performed between phase levels within amplitude conditions with significance indicated by *. Bonferroni corrected did not find any of the means to significantly differ from zero; 90° = peak; *p ≤ 0.05.