Systems Theory, Emergent Properties, and the Organization of the Central Nervous System

Abstract

The Central Nervous System can be understood as an organization whose levels have been established throughout evolution. In this organization, the cerebral hemispheres occupy the highest level of a hierarchical open system wherein the function of the brain is to match relationships among objects in the surrounding environment. The outer portion of the cerebral hemispheres is comprised of vertical arrays of cell bodies (minicolumns) whose close apposition provide for the cerebral cortex. Thalamic afferents terminate in the middle layers of the minicolumns and are integrated into microcircuits by vertical connections to more superficial and deeper layers. These repeating microcircuits comply with a definition for modules as weak linkages connecting elements within the module are more abundant than those between the modules. Electrophysiological studies with conformal multielectrode recording arrays have defined the transmission codes by which minicolumns give rise to executive functions, e.g., task-related selection. The emergence of minicolumnar functions appears to be prompted by physical constraints where laws of conservation guide the self-organization of minicolumns during brain development and ageing. The fact that minicolumns exhibit scalar properties relating pyramidal cell size and minicolumnar core size, rotational symmetry, and conservation of translational movements helps to conceptually organize the cytoarchitecture of the isocortex.