From Neural Dynamics to Cell Assemblies

Abstract

In this chapter I want to introduce a certain type of mathematical brain model. Such models arise from the desire to understand the dynamics in a large network of interconnected neurons. Thus they study the flow of activity through a neuronal network on the basis of comparatively simple assumptions on the dynamics of the individual neurons (and synapses) and on the pattern of their connectivity. The results are usually interpreted in comparison with introspective, psychological, or psychophysical experiences. This kind of interpretation, of course, tends to be very speculative, especially since usually not the whole brain is modeled but just some part of it (e.g., the cortex, the hippocampus, the visual cortex, the cerebellum), and it remains unclear to what degree other parts of the brain contribute to the experiences referred to.

Common events in the baby’s experience repeatedly excite groups of neurons in the cortex. The neurons that are excited when one of these things happens are not the same every time, but there is a common core of ones that are excited every time. The core neurons therefore tend to become connected with one another in a single system that we will call a cell-assembly. Many of these neurons are in closed self-re-exciting circuits and so … the system can continue to be active after outside stimulation has ceased. D. O. Hebb, 1958