People with schizophrenia have reduced neural prediction-error signals (mismatch negativity in stable contexts, P300 in volatile contexts) that are specific to the schizophrenia spectrum, whereas altered brain connectivity—decreased intrinsic connectivity in the left primary auditory cortex and right inferior frontal gyrus (IFG), reduced bottom-up and increased top-down frontotemporal connectivity—occurs across all participants as psychotic experiences intensify. Impaired sensory learning behavior was linked to lower intrinsic connectivity in the IFG, which also decreased with greater severity of psychotic experiences. The findings suggest that distinct neural mechanisms underlie schizophrenia-specific deficits versus general psychosis-related connectivity changes.
The prefrontal cortex's role in consciousness is debated: frontal theories say it is necessary, while sensory theories argue consciousness arises from the posterior cortex alone. Re-analyzing EEG data from 30 participants in a no-report inattentional blindness paradigm, dynamic causal modeling estimated effective connectivity between prefrontal and posterior cortices. A data-driven search could not support either theory, but a hypothesis-driven analysis showed both could explain the data, with a slight preference for frontal theories. A model disabling backward connections within the posterior cortex explained awareness better (53%) than one without prefrontal-to-sensory backward connections. The findings suggest a subtle frontal contribution and call for revising current theories.