Attention Renders Sensory Contents into Conscious State via Content-invariant Frontal-Posterior Coupling in Humans

Abstract Although attention promotes conscious perception, how it does so remains unclear. Human neuroimaging research has richly characterized attentional modulation upon visual processing, yet it remains unclear which of its components act as precursors of consciousness, which constitute consciousness itself, and which merely reflect post-perceptual, response-related operations. Combining a newly developed psychophysical paradigm with intracranial electroencephalography (iEEG), we addressed this issue in the human brain. Behavioral results from the psychophysical experiment and its replication showed that top-down attention plays a preparatory role: it promotes visual consciousness not directly, but by enabling attentional capture specific to salient stimuli. iEEG then revealed that early attentional preparation unfolds in a module-dependent manner, differing between the posterior brain (sensory module) and the frontal brain (attention module). We further dissociated two neural signals—one tracking the rapid rise and decay of visual consciousness, the other supporting post-perceptual responses through global late (>600 ms) content retrieval—thereby isolating a conscious window (~250–550 ms) from its preconscious and post-perceptual confounds. Finally, coherence analyses revealed the predicted frontal–posterior coupling (~4 Hz) restricted to this window. Critically, this coupling encoded only the binary on/off state of conscious awareness, whereas fine-grained contents were persistently encoded in the posterior brain. Together, these findings provide pioneering evidence that attention does not promote consciousness directly by itself; rather, it engages a content-invariant frontal–posterior coupling mechanism—not an earlier sensory enhancement mechanism or a later global content broadcast mechanism—to render sensory contents into an explicit conscious state.