Where is the self? A neuroanatomical theory of consciousness

Abstract

The enigmatic nature of the experience of self‐awareness is examined in the light of recent discoveries and, on this basis, combined with inferences derived introspectively from the from the experience of the phenomenon itself; a specific physical locus of this experience within the human brain is deduced‐proposed. The fundamental premise in this work is that whereever consious self‐awareness is generated, the neuronal structure(s) invloved must continually have access to an extremely precise representation of information derived from the sense of vision plus a great variety of other kinds of information so as to permit it to make decisions regarding actions (movements and their implementation) that promote the survival and perpetuation of the biological system in which the self is generated. First, a definitive set of criteria that define most of the inputs to and operations carried out by the self‐awareness entity were assembled. This ensemble of functions was then compared with the connnections and possible roles of specific neuroanatomical structures described in published literature, particularly the recent literature and particulary that concerned with the sense of vision. It was discovered that only one brain stucture receives the prerequisite information from the sense of vision plus information derived from cortical memory stores plus a variety of other relevant sources needed to generate a coherent sense of selfness. This structure is the superior colliculus of the tectum. The Superior colliculi not only recieve a highly precise retinotopic representation of inputs to the eyes but also receive inputs from a great variety of other structures, including many areas of the cerebral cortex, vestibular inputs, auditory inputs, “affective” inputs, and inputs that putatively define the positions of the eyes and of the head. This information, it is deduced, not only allows this structure, to generate a continuing synthesis of representations, of the self‐vs.‐enviornment, but also allows a part of it to assess the significance (probable meaning) of these integrated inputs with respect to the selection of and implementation of actions that serve the interests of the physical structure in which the self‐experience is generated. The function of memory in this system not only invloves the continually updated representation of where the self is with respect to items and objects in its environment, but also provides means through which the relevance of recorded experiences representing the past may be caused to affect the decision‐making process. Because there is no evidence in the literature that the superior colliculi project a visuotopic map to any other brain structure, the decision‐making process per se is also deduced to be carried out by the superior colliculi, which has numerous output connections to the prerequisite parts of the brain. The part of the superior colliculi that generates self‐awareness and instructs the motor parts of the brain regarding actions selected on the basis of their probable effects and affects is basically proposed to be an executor of options it receives from memory rather than a formulator of action specifics. The fact that destruction of the superior colliculi does not result in unconsciousness, but rather in confused behavior, is not inconsistent with the role proposed for them. The generation of a “coherent” map of self‐vs‐environment is suggested to result from a shifting of the map of the environment (derived form immediate and earlier memory) with respect to the spatial map derived from the sense of vision and hearing. This set of deductions appears suited to explain many major aspects of the enigma of self and self‐awareness.