Visual experience is unfathomably rich, not sparse. Seeing involves three levels: high-level object and scene categorizations, mid-level feature groupings, and a fundamental spatial field of spots and their relations. Seeing objects requires seeing the groupings that compose them, and seeing groupings requires seeing the spatial field that grounds them. Even the basic feeling of spatial extendedness implies rich phenomenal structure. Much of what we see cannot be used, reported, or remembered, yet we see it.
Simultaneous recordings from frontal, parietal, striatal, and thalamic regions in macaques during wakefulness, sleep, and anesthesia, along with deep-brain thalamic stimulation, show that parietal cortex, striatum, and thalamus contribute more to the level of consciousness than frontal cortex. This supports Integrated Information Theory over Global Neuronal Workspace Theory and Higher-order Theories, but Integrated Information Theory does not account for subcortical structures like the striatum. The authors propose that thalamo-striatal circuits have a cause-effect structure that generates integrated information.