This book is a succinct introduction to the orienting of attention.

I propose that primary conscious awareness arises from synchronized activity in dendrites of neurons in dorsal thalamic nuclei, mediated particularly by inhibitory interactions with thalamic reticular neurons. In support, I offer four evidential pillars: consciousness is restricted to the results of cortical computations; thalamus is the common locus of action of brain injury in vegetative state and of general anesthetics; the anatomy and physiology of the thalamus imply a central role in consciousness; neural synchronization is a neural correlate of consciousness.

The centrencephalic theory of consciousness cannot yet account for some evidence from both brain damaged and normally functioning humans that strongly implicates thalamocortical activity as essential for consciousness. Moreover, the behavioral indexes used by Merker to implicate consciousness need more development, as, besides being somewhat vague, they lead to some apparent contradictions in the attribution of consciousness. (Published Online May 1 2007).