Chemical Waves and Dendrites Navigation during Self-Wiring of Neural Nets

Abstract

In mammals, the precise structure of the neural circuits in the brain cannot be stored genetically, since the DNA lacks sufficient memory for such amounts of information. In humans for example, the DNA consists of about 108 bases and there are approximately 1015 synaptic connections. On the other hand, the network development is not entirely random. It appears that the degree of randomness in the synaptic connections is large on the micro scales (<1 mm) but on the macro scale (>2 cm) the organization is almost entirely deterministic [1]. A fundamental question is, then, what principles determine the network structure, and in particular what is the role of randomness vs. stored genetic information of its generation process? Furthermore, since the development is not entirely deterministic, what is the effect of the environment, i.e. external stimulus, on the network organization? Naturally, when we discuss the principles that organize the network, we assume that more than one structure of connections is possible. Hence we face the question of characterizing the different possible networks, and their effect on the network functioning.