The Principle of Controlling Neuronal Dynamics in Neocortex: Rapid Reorganization and Consolidation of Neuronal Assemblies

Abstract

The neuronal substrate for information processing in the neocortex consists of a highly divergent and sparsely connected network of neurons. In order to cope with the complexity of real-world information in time and space, the operations of neuronal circuits have to include both processes of rapid reorganization as well as the generation of stabilized representations. The brain has to find its equilibrium between these two seemingly antagonistic modes of processing, adaptivity and consolidation. Most synapses in the cortex cannot change their strength within a few seconds. On the one hand, rapid changes in functional connectivity need to be implemented by dynamic and reversible neuronal operations. On the other hand, some of the information once represented by dynamic neuronal operations is needed for future processing. Therefore, a trace has to be formed in the cortical circuitry that can be instantaneously re-activated upon occurrence of the same or a similar input pattern. This chapter will describe the neuronal mechanisms for dynamic grouping of cortical responses by means of millisecond-precise synchronisation and discuss whether neuronal assemblies provide a suitable concept to understand the equilibrium between cortical adaptivity and consolidation.