Different theories explain how subjective experience arises from brain activity. An open science adversarial collaboration directly juxtaposed integrated information theory (IIT) and global neuronal workspace theory (GNWT). Human participants (n = 256) viewed suprathreshold stimuli for variable durations while neural activity was measured with fMRI, MEG, and intracranial EEG. Information about conscious content was found in visual, ventrotemporal, and inferior frontal cortex, with sustained responses in occipital and lateral temporal cortex reflecting stimulus duration, and content-specific synchronization between frontal and early visual areas. These results align with some predictions of IIT and GNWT but substantially challenge key tenets of both theories, including a lack of sustained posterior cortex synchronization for IIT and a lack of ignition at stimulus offset and limited prefrontal representation for GNWT.
Transitions in conscious visual perception involve two distinct neural mechanisms: boundary fading in visual cortex, marked by increased excitability and reduced alpha-band activity indicating a shift in excitation-inhibition balance, and higher-order perceptual monitoring in motor cortex, reflected by decreased high-alpha and beta-band activity. Microsaccadic eye movements, which delay the illusion, selectively reset both processes. These findings support a hierarchical framework where visual and motor systems jointly shape changes in conscious experience.
An open science adversarial collaboration directly juxtaposed Integrated Information Theory (IIT) and Global Neuronal Workspace Theory (GNWT) by investigating neural correlates of visual experience. 256 human subjects viewed suprathreshold stimuli for variable durations while neural activity was measured with fMRI, MEG, and ECoG. Information about conscious content was found in visual, ventro-temporal, and inferior frontal cortex, with sustained responses in occipital and lateral temporal cortex reflecting stimulus duration, and content-specific synchronization between frontal and early visual areas.
People can learn to associate a face with a later shock even when they are unaware of seeing the face, challenging the view that conscious awareness is necessary for trace fear conditioning. Using magnetoencephalography (MEG) to record amygdala activity, the authors observed rapid neural responses (around 170-200 milliseconds) during the interval between the unperceived face and the shock. These results suggest that unperceived faces can serve as signals for impending threat and that automatic amygdala activation contributes to this learning. The study also describes a novel MEG methodology for investigating subcortical structures.