Scientific Understanding of Consciousness
At the current status of neuroscience, it would not be meaningful to make a detailed diagram of the mechanisms of consciousness. However, a gross diagram can perhaps be informative and helpful.
· All sensory information except olfactory passes through, and is potentially gated by, the thalamus.
· The thalamocortical system connects areas in the cortex with areas in the thalamus. Neural activity in this thalamocortical system is continuous from the prenatal embryo until death. The lack of neural activity in this thalamocortical system is a marker for brain death.
· The thalamus receives feedback from all cortical processing areas.
· The thalamocortical reentry loops connect many areas of the cortex, providing dynamic neural connectivity.
· A dynamically changing subset of neural activity in the thalamocortical system is the dynamic core mediating the emergent property of consciousness.
· The extent and intensity of neural activity necessary for minimal consciousness is currently unknown but may be more clearly understood in future decades. Neural activity varies greatly during a 24-hour period of waketime activities followed by daily sleep and dreaming.
· Local cortical neuronal assemblies function on the basis of about 20 ms; longer corticocortical connections, which may include a few synapses and may include paths via thalamocortical reentry loops, may entail 100-200 ms, yielding an overall recursive response of perhaps a half second for Bayesian processes.
· Recurrent functionality in local neuronal circuits, along with longer corticocortical recursive connectivity, together with recursive functionality in the thalamocortical system give rise to an overall cacophony of oscillatory neural signals in the EEG spectrum with the 1/f distribution of pink noise.
· The thalamus provides selective functionality for attention.
· Executive function of working memory in the cortex provides attention-regulating selective functionality to the thalamus.
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