Right-hemisphere frontoparietal oscillations precede conscious reports of visual targets
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What neural events precede conscious reports? Hemisphere-asymmetric frontoparietal networks are causally related to conscious perception (Bartolomeo et al., 2025; Kaufmann et al., 2024), but their spectrotemporal dynamics remain unclear. Here, we examined frontoparietal gamma oscillations occurring before a near-threshold target during the understudied pre-target period. In 67% of trials, a supra-threshold visual cue appeared near the target placeholder box (cued condition), indicating a higher probability that the target would appear at that location. In the remaining 33% of trials (uncued condition), the target appeared at the opposite location. We measured whole-brain activity using magnetoencephalography and analyzed gamma-band oscillations, coherence, and amplitude coupling with theta-phase in 16 regions of interest involved in attentional and perceptual processes (Martín-Signes et al., 2024). Results revealed that: (1) Report of cued targets was preceded by gamma-band oscillations in the right-hemisphere (RH) superior frontal gyrus, and by theta-gamma phase-amplitude coupling in the RH superior parietal region, suggesting preparatory attention. (2) Report of uncued targets was preceded by RH inferior parietal gamma oscillations and by coherence between RH superior and middle frontal regions, supporting an anticipatory “lookout” mechanism involved in monitoring for unexpected stimuli and rapidly redirecting attention to them. (3) Unreported targets were preceded by gamma-band oscillations in the left-hemisphere superior parietal lobe and by higher coherence in the left-hemisphere frontoparietal networks, suggesting a pre-target bias contributing to omission errors (Bartolomeo et al., 2025). These spectrotemporal signatures of attention in hemisphere-asymmetric frontoparietal networks shape predictive processing and perceptual bias, and predict conscious reports or their absence.
Significance statement
The ability to attend to spatial cues in anticipation of relevant stimuli is essential for efficient behavior. We identify three spectrotemporal dynamics by which frontoparietal networks shape conscious visual perception. Gamma-band oscillations in the right-hemisphere superior frontal gyrus and theta-gamma coupling in the right superior parietal region preceded conscious reports of cued near-threshold targets. When targets appeared in the uncued location, requiring attentional reorienting, conscious report was preceded by gamma-band oscillations in the right-hemisphere intraparietal sulcus and by coherence-based communication between the right-lateralized superior and middle frontal gyri. Conversely, left-hemispheric gamma-band oscillations and coherence during the cue-target interval disrupted conscious report. These results characterize the neural dynamics leading to conscious perception by unveiling the role of hemisphere-asymmetric frontoparietal spectral dynamics.