The probability of neural connexions

Abstract

In some areas of a nervous system there is no obvious plan of connexions. If it is assumed, first, that in these areas fibre growth is random, and secondly, that connexions are formed if axon and dendrite approach within a critical distance, there are certain mathematical consequences. If fibre density is defined and measured in a particular way it is possible to derive a formula for the average number of connexions between an axonal and a dendritic system. If an axonal system is embedded in a population of similar dendritic systems it is possible to calculate how many of the latter have a given number of connexions with the axonal system. For neurons in the striate and motor areas of the cortex of the cat some of the necessary anatomical data are known, and numerical values are computed from the formulae.