How can we detect ensemble coding by cell assembly?

Abstract

The present chapter discusses why cell-assembly coding, i.e., ensemble coding by functionally connected neurons, is an appropriate view of the brain's neuronal code and how it operates in the working brain. The cell-assembly coding has two major properties, i.e., partial overlapping of neurons among assemblies and connection dynamics within and among the assemblies. The former is the ability of one neuron to participate in different types of information processing. The latter is the capability for functional synaptic connections, detected by synchrony of firing of the neurons, to change among different types of information processing. Examples of experiments which detected these two major properties are then given. Several relevant points concerning the detection of cell assemblies and dual-coding by cell assemblies and single neurons are also enumerated. Finally, technical and theoretical improvements necessary for future researches of cell-assembly coding are discussed. They include an unique technique of spike-sorting with independent component analysis and theories of sparse coding by distributed overlapped assemblies and coincidence detection as a role of individual neurons to bind distributed neurons into cell assemblies.