The centrecephalon and thalamocortical integration: Neglected contributions of periaqueductal gray

I have argued in other work that emotion, attentional functions, and executive functions are three interpenetrant global state variables, essentially differential slices of the consciousness pie. This paper will outline the columnar architecture and connectivities of the PAG (periaqueductal gray), its role in organizing prototype states of emotion, and the re-entry of PAG with the extended reticular thalamic activating system (“ERTAS”). At the end we will outline some potential implications of these connectivities for possible functional correlates of PAG networks that are just starting to be mapped. Overall, we will look at many lines of evidence that PAG should be conceptualized as a peri-reticular structure that has a foundational role in emotion, in generating the meaningful organization of behavior by the brain through prototype emotional states, and in allowing the various emotional systems to globally influence and tune both the forebrain and brainstem. Finally, we address implications of these concepts for what is currently understood about consciousness, underlining the need for somewhat more humility within consciousness studies about our current level of understanding of consciousness in the brain, combined with a deeper appreciation of the intrinsic connections between emotion and consciousness. One hopes that more concerted empirical interest in structures underneath the thalamus, combined with a deeper appreciation for the fundamental role that organismic and social value must have in bootstrapping awareness in the developing brain, would begin more widely to influence the fundamental lines of neuroscientific research in both emotion studies and consciousness studies.