The nested neural hierarchy and the self

Abstract

In spite of enormous recent interest in the neurobiology of the self, we currently have no global models of the brain that explain how its anatomical structure, connectivity, and physiological functioning create a unified self. In this article I present a triadic neurohierarchical model of the self that proposes that the self can be understood as the product of three hierarchical anatomical systems: The interoself system, the integrative self system, and the exterosensorimotor system. An analysis of these three systems and their functional features indicates that the neural hierarchy possesses features of both non-nested and nested hierarchies that are necessary for the creation of a unified consciousness and self. These functional properties also make the central nervous system a biologically unique entity unlike anything else in nature.

Introduction

The question I address in this paper is: “How does the brain create a self?” For the purposes of the present inquiry, I define the self by three critical features – its relationship to consciousness, its unity, and its persistence in time. Thus, I propose the following definition: the self is a unity of consciousness in perception and action that persists in time (Feinberg, 2009). This definition of the self presupposes that there must be something conscious, that the consciousness in question must exist in some sense unified, and that this consciousness possesses a temporal aspect. In other words, whatever there is “something that it is like to be” any conscious organism (Nagel, 1974) must be unified and endure beyond the instantaneous moment of that organism’s perception and action. While there is an emerging “neuroscience of the self” that addresses important issues regarding which brain structures are critical for the creation and maintenance of the self, we currently lack unifying models that “bridge the gap” between the microstructure, macrostructure, connectivity and physiology of the brain and the unified sense of self as subjectively experienced. In this article I present a neurobiological model of the self but focus primarily on the issues of the self as a unity of consciousness in perception and action. For a discussion of the issue of its persistence in time, see Feinberg, 2009.