The partial awareness hypothesis proposes that people can become conscious of distinct properties of an object independently, from low-level features to complex forms. In a visual word masking experiment adjusted to each participant's perception threshold, participants perceived individual letters but not whole words in about half of trials, corresponding to partial awareness. Magnetoencephalography (MEG) recordings showed that partial awareness, compared to no awareness, involved suppression of alpha oscillations in left temporal and parietal cortices. Functional connectivity analysis revealed strong connections between the temporal seed and other language network regions. The findings suggest that engagement of language regions, indexed by alpha power suppression, establishes and maintains conscious representations of pre-lexical units.
Conscious perception of a faint touch depends not only on brain activity in the sensory cortex but also on the state of larger brain networks just before the stimulus arrives. In a magnetoencephalography study, participants performed a near-threshold tactile detection task. Before correctly detected stimuli, alpha and beta power were reduced in the somatosensory region opposite the stimulated hand, and event-related responses were stronger afterward. Graph analysis revealed that the right primary somatosensory cortex showed increased integration in the theta band and decreased integration in the beta band before detection. These findings suggest that a reduction of irrelevant functional connections helps tune neural pathways for conscious perception.
Brain regions crucial for hearing a faint sound are already coupled before the sound arrives, forming pre-established pathways that influence whether the sound is consciously perceived. Using magnetoencephalography and graph theory, the study found that in a near-threshold auditory task, the left auditory cortex behaved like a hub and was more integrated into the brain's functional network prior to conscious perception, while right auditory regions were decoupled from non-auditory areas. Local excitability, measured by decreased alpha power in the auditory cortex, also increased before conscious percepts. These connectivity and excitability states were largely independent of each other.