To See or Not to See: Pre-stimulus Alpha Phase Predicts Visual Awareness

By Kyle E. Mathewson, Gabriele Gratton, Monica Fabiani, Diane M. Beck, Tony Ro. Journal of Neuroscience, 2009

860 citations recorded by the source corpus.

We often fail to see something that at other times is readily detectable. Because the visual stimulus itself is unchanged, this variability in conscious awareness is likely related to changes in the brain. Here we show that the phase of EEG α rhythm measured over posterior brain regions can reliably predict both subsequent visual detection and stimulus-elicited cortical activation levels in a metacontrast masking paradigm. When a visual target presentation coincides with the trough of an α wave, cortical activation is suppressed as early as 100 ms after stimulus onset, and observers are less likely to detect the target. Thus, during one α cycle lasting 100 ms, the human brain goes through a rapid oscillation in excitability, which directly influences the probability that an environmental stimulus will reach conscious awareness. Moreover, ERPs to the appearance of a fixation cross before the target predict its detection, further suggesting that cortical excitability level may mediate target detection. A novel theory of cortical inhibition is proposed in which increased α power represents a “pulsed inhibition” of cortical activity that affects visual awareness.

Subfields: Cognitive Neuroscience

View Paper: https://www.semanticscholar.org/paper/5a3e177c76d63866c2f4fa0b4059edc0f345d218

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Citations in the corpus

On the Role of Prestimulus Alpha Rhythms over Occipito-Parietal Areas in Visual Input Regulation: Correlation or Causation? (2010, neutral): “It is conceivable that target visibility might further vary with the time point of testing within an alpha cycle, because visual perception not only fluctuates with alpha power but also with alpha phase (Busch et al., 2009; Mathewson et al., 2009).”
EEG and MEG: relevance to neuroscience. (2013, background): “This may be concluded from the study of Mathewson et al. (2009), who showed that the phase of EEG a rhythm can reliably predict subsequent detection of visual stimuli and stressed that a power increases represent a form of ‘‘pulsed inhibition’’ of cortical excitability that modulates 1120 Neuron…”
The Role of Alpha-Band Brain Oscillations as a Sensory Suppression Mechanism during Selective Attention (2011, positive): “Mathewson et al. (2009) moreover reported that phase of ongoing alpha predicted detection ability, a very interesting finding in need of further investigation in our view. a stream of letter stimuli to both visual hemifields.”
α-Oscillations in the monkey sensorimotor network influence discrimination performance by rhythmical inhibition of neuronal spiking (2011, positive): “In support of this notion, it has recently been demonstrated that perception is modulated by the prestimulus phase of the α-rhythm (31, 32).”
Neurophysiological and Computational Principles of Cortical Rhythms in Cognition (2010, neutral): “In human studies, it was reported that detection of a near-threshold stimulus depends on the stimulus onset time relative to the phase of ongoing 5–10 Hz oscillations in the frontal cortex (137) or parietal cortex (657).”
The Berlin Brain–Computer Interface: Non-Medical Uses of BCI Technology (2010, neutral): “Many studies in cognitive neuroscience have set out to find neuronal correlates that explain this variability (e.g., Fernández et al., 1999; Thut et al., 2006; Chen et al., 2008; Mathewson et al., 2009; Schubert et al., 2009).”
Entrainment of brain oscillations by transcranial alternating current stimulation. (2014, positive): “Specifically, it has been demonstrated that high prestimulus alpha power is predictive of decreased visual detection performance in a phase-dependent fashion [15, 25, 26].”
The Theta-Gamma Neural Code (2013, neutral): “2) probably accounts for why perception is dependent on alpha phase (Busch et al., 2009; Dugue et al., 2011; Mathewson et al., 2009).”
Oscillatory entrainment to our early social or physical environment and the emergence of volitional control (2022, background): “…systematically to the excitability of neural populations and the magnitude of event-related responses (Busch et al., 2009; Lakatos et al., 2008; Mathewson et al., 2009; VanRullen et al., 2011) (although see (Ruzzoli et al., 2019)); accordingly, sensory stimuli that are delivered during a high…”
Rhythmicity Revisited: Evidence from Robust Behavioral Oscillations (2025, unknown): “The instantaneous phase of ongoing rhythms predicts performance in perception 17,18 , attention 13,19 , and memory 20,21 , reinforcing the view that neural computations are timed by oscillatory activity.”
Temporal expectation based on the duration variability modulates alpha oscillations during working memory retention (2022, background): “For example, decreased alpha power over posterior brain regions prior to the presentation of target items has been consistently associated with better performance for target detection or discrimination (Mathewson et al., 2009; Thut et al., 2006; van Dijk et al., 2008).”
Cell type-specific excitability probed by optogenetic stimulation depends on the phase of the alpha oscillation (2022, background): “Empirically reported excitable alpha phase 472 varies from study to study and across regions [14, 15, 58, 64].”