Probing cortical excitability using rapid frequency tagging

Abstract

Frequency tagging has been widely used to study the role of visual selective attention. Presenting a visual stimulus flickering at a specific frequency generates so-called steady-state visually evoked responses. However, frequency tagging is mostly done at lower frequencies (<30 Hz). This produces a visible flicker, potentially interfering with both perception and neuronal oscillations in the theta, alpha and beta band. To overcome these problems, we used a newly developed projector with a 1440 Hz refresh rate allowing for frequency tagging at higher frequencies. We asked participants to perform a cued spatial attention task in which imperative pictorial stimuli were presented at 63 Hz or 78 Hz while measuring whole-head magnetoencephalography (MEG). We found posterior sensors to show a strong response at the tagged frequency. Importantly, this response was enhanced by spatial attention. Furthermore, we reproduced the typical modulations of alpha band oscillations, i.e., decrease in the alpha power contralateral to the attentional cue. The decrease in alpha power and increase in frequency tagged signal with attention correlated over subjects. We hereby provide proof-of-principle for the use of high-frequency tagging to study sensory processing and neuronal excitability associated with attention.

Alpha oscillations do not implement gain control in early visual cortex but rather gating in parieto-occipital regions

“…6) related to attention (p < 0.001 for left and as well as right sensors of interest, paired t-test). These results are in line with earlier findings (Zhigalov et al, 2019) as well as Figure 3 showing that attention increases the magnitude of the tagged response.…”

“…These results showed a negative correlation (r = -0.63 (Spearman correlation), p < 0.005) between the modulation of power at the alpha and tagging responses, which is in line with earlier observations (Zhigalov et al, 2019). Similarly, we correlated individual AMI in the alpha band and the response latencies (Fig.…”

“…There have been some attempts to assess the relationship between power of the alpha oscillations and the tagging response in attentional tasks. These studies indicate that the frequency tagging signal is not related to alpha magnitude on a trial-by-trial basis (Zhigalov et al, 2019;Gundlach et al, 2020). This then begs the question of what is the functional role of alpha oscillations in attention tasks?…”

“…Interestingly, while alpha power decreases contra-laterally to attended stimulus (and increases ipsi-laterally), power of the high-frequency tagging response shows an opposite effect (e.g. (Gulbinaite et al, 2019;Zhigalov et al, 2019). There have been some attempts to assess the relationship between power of the alpha oscillations and the tagging response in attentional tasks.…”

Limits of subjective and objective vection for ultra-high frame rate visual displays

“…The stimulus was back-projected onto the screen using a DLP LED projector (PROPixx, VPixx Technologies Inc., Montreal, Canada). The PROPixx operated in a specialized high refresh rate video sequencer mode called QUAD4X developed by VPixx Technologies (Alais et al, 2016;Balsdon et al, 2018;DeSimone & Schneider, 2019;Schweitzer & Rolfs, 2019;Zhang et al, 2019;Zhigalov et al, 2019). In short, the computer's graphic card (Titan V, Nvidia, Santa Clara, CA) transmits a 1920 x 1080 pixels image at 120 FPS.…”