Arnold Trehub

Nature Network Groups hosted an invited workshop on 'Theories of Consciousness' during the second semester of 2009. There were presentations by each of 15 authors active in the field, followed by debate with other presenters and invitees. A week was allocated to each of the theories proposed; general discussion threads were also opened from time to time, as seemed appropriate. We offer here an account of the principal outcomes. It can be regarded as a contemporary, 'state of the art' snapshot of thinking in this field.

Activation of the brainʼs putative retinoid system has been proposed as the neuronal substrate for our basic sense of being centered within a volumetric surround –- our minimal phenomenal consciousness (Trehub 2007). Here, the assumed properties of the self-locus within the retinoid model are shown to explain recent experimental findings relating to the out-of-body-experience. In addition, selective excursion of the heuristic self-locus is able to explain many important functions of consciousness, including the effective internal representation of a 3D space on the basis of 2D perspective depictions. Our sense of self-agency is shown to be a natural product of the role of the heuristic self-locus in the retinoid mechanism

A particular system of brain mechanisms, called the retinoid system, is proposed as the evolutionary adaptation responsible for the existence of subjectivity and our sense of being here in a surrounding 3D world. The structural and dynamic properties of the retinoid system successfully predict a novel conscious experience in which the brain constructs a vivid visual representation of an object moving in space without a corresponding image projected to the retinas. Implications of the retinoid system for human creativity and our scientific understanding of the universe are suggested.

Over a decade ago, I introduced a large-scale theory of the cognitive brain which explained for the first time how the human brain is able to create internal models of its intimate world and invent models of a wider universe. An essential part of the theoretical model is an organization of neuronal mechanisms which I have named the Retinoid Model (Trehub, 1977, 1991). This hypothesized brain system has structural and dynamic properties enabling it to register and appropriately integrate disparate foveal stimuli into a perspectival, egocentric representation of an extended 3D world scene including a neuronally-tokened locus of the self which, in this theory, is the neuronal origin of retinoid space. As an integral part of the larger neuro-cognitive model, the retinoid system is able to perform many other useful perceptual and higher cognitive functions. In this paper, I draw on the hypothesized properties of this system to argue that neuronal activity within the retinoid structure constitutes the phenomenal content of consciousness and the unique sense of self that each of us experiences. Trehub, A. (1977). Neuronal models for cognitive processes: Networks for learning, perception, and imagination. _Journal of Theoretical Biology_ 65: 141-169. Trehub, A. (1991). _The Cognitive Brain_. MIT Press.