Time-dependent modulation of visual gamma oscillations points to increased neural plasticity in Visual Snow Syndrome
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Date
2025-01-24
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MSUPE
Abstract
To explore potential alterations in E/I balance and neuroplasticity in VSS, we recorded visual gamma oscillations with magnetoencephalography in 26 patients with VSS and 27 controls participants. Excitatory drive was regulated by presenting participants with high-contrast circular gratings, static or drifting at one of four rates (0.6˚/s, 1.2˚/s, 3.6˚/s, or 6.0˚/s).
Description
Twenty-six patients were recruited from an online VSS community and through clinic referrals. All patients underwent neurological examination, during which detailed information about their neurological and visual symptoms was collected. Thirteen subjects from the patient group reported visual snow (VS) from early childhood (approximately before age 10), while the other 13 developed VS after age 14. Subjects who developed VSS due to substance abuse were excluded from the study. Nearly all participants (24 out of 26) were medication-free. Two participants were taking antidepressants: one on venlafaxine (75 mg daily) and another on escitalopram (5 mg daily), both of whom had been on their respective medications for more than three months.
We also recruited 27 neurologically healthy control participants from the community, matched for sex and age. The characteristics of the subjects are presented in Table 1. All subjects were asked to complete a Russian version of the Visual Discomfort Scale (Conlon, 1999), which assesses unpleasant somatic and perceptual side effects of pattern viewing. They were also asked to complete the Russian version of the State-Trait Anxiety Inventory (Spielberger, 1983).
The recording session started with two resting conditions: a 5-minute period with eyes closed, followed by a 5-minute period with eyes open. While the 'eyes closed' condition was not analyzed in this study, the 'eyes open' condition was used to estimate resting-state heart rate variability.
The visual task (Figure 1A) was presented immediately after the resting state. Participants watched a sequence of large high-contrast circular gratings (18˚, 100% contrast, spatial frequency 1.66 cycles per degree) that either drifted toward the center at one of four velocities (0.6˚/s, 1.2˚/s, 3.6˚/s, or 6.0˚/s) or remained static (Figure 1A). The presentation time for each stimulus ranged randomly from 1.2 to 1.6 seconds. After this period, the stimulus disappeared. Participants were instructed to press a button as soon as this happened. If the button was not pressed within 1 second after stimulus disappearance, the trial was considered a 'missed trial', and the text "You're late!" was shown to the participant for 1.0 second. If the subject pressed the button before 150 ms after stimulus disappearance, the trial was considered a 'commission error trial'. All trials started with a fixed 1.2 s prestimulus interval during which a fixation cross was presented in the center of the visual field, followed by the presentation of the stimulus. The new trial started immediately after the button press. To reduce fatigue and boredom, participants were shown short (3–6 s) cartoon animations after every 5-10 gratings. For each participant, 90 gratings of each type were presented.
Subjects were offered a break in the middle of the session. For all subjects except two participants with VSS, data were available for both parts of the session: before and after the break (450 trials in total). For one VSS participant, only 200 trials before the first break were available due to a technical error. In all participants, uninterrupted data were available for 1-137 trials.
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Citation
Orekhova, E.V., Naumova, S.M., Obukhova, T.S., Plieva, A.M., Prokofiev, A.O., Petrokovskaia, A.V., Stroganova, T.A. (2025). Time-dependent modulation of visual gamma oscillations points to increased neural plasticity in Visual Snow Syndrome: Data set. RusPsyData: Psychological Research Data and Tools Repository. Moscow. https://doi.org/10.48612/MSUPE/fb2u-9t6p-9vv7 (In Russ.).