Abstract
Our own work, as well as that of others, has demonstrated the oscillatory nature of visual perception. For example, the phase of ongoing cortical oscillations influences the likelihood of visual-target detection, such that a near-threshold stimulus is more likely to be detected if it occurs during a high-excitability state. Debate persists, however, regarding which specific frequencies influence visual-target detection. Some recent studies have demonstrated phase-behavior relationships at theta and alpha frequencies (5–14 Hz); other studies, which focused on the interaction between attention and visual-target detection, have instead emphasized the importance of low-delta (1–2 Hz) frequencies. Here, we recorded high-density EEG during a visual sustained-attention task to investigate phase-behavior relationships across a broad range of frequencies (1–50 Hz). We further endeavored to examine inter-subject differences in the frequencies that underlie behavioral performance. Subjects responded whenever they detected a near-threshold visual stimulus, which either co-occurred with an auditory cue or anytime up to 5 seconds thereafter. Our data reveal that the prestimulus oscillation most consistently linked with detection across subjects had a frequency of approximately 1 Hz. Detection was also significantly linked to the phase of oscillations at higher frequencies (e.g., theta and alpha), but the specific frequencies of these other phase-behavior relationships varied substantially across subjects. A closer examination of the data further revealed that the phase-behavior relationship at higher frequencies was sometimes mediated by phase-power coupling with the 1-Hz oscillation. That is, power at higher frequencies was dependent on phase of the 1-Hz oscillation. Binning trials based on the phase of the 1-Hz oscillation revealed a stronger phase-behavior relationship at higher frequencies. Overall, our results shed light on the complex interplay between visual perception and oscillatory activity on different temporal scales. We further demonstrate that the specific frequencies linked to visual-target detection vary on a subject-by-subject basis.
Meeting abstract presented at VSS 2012