Optimal axonal and dendritic branching strategies during the development of neural circuitry

TL;DR

This study uses computational modeling to explore optimal axonal and dendritic branching strategies during neural development, revealing how different strategies enhance target finding efficiency and connectivity accuracy.

Contribution

It introduces a computational framework demonstrating distinct optimal branching rules for axons and dendrites, explaining observed neural connectivity patterns.

Findings

Branching accelerates target identification via parallel search.

Proximity-based branching reduces erroneous connections.

Different optimal strategies for axons and dendrites are identified.

Abstract

In developing brain, axons and dendrites are capable of connecting to each other with high precision. Recent advances in imaging have allowed for the monitoring of axonal, dendritic, and synapse dynamics in vivo. It is observed that the majority of axonal and dendritic branches are formed 'in error', only to be retracted later. The functional significance of the overproduction of branches is not clear. In this study, we use a computational model to investigate the speed and efficiency of different branching strategies. We show that branching itself allows for substantial acceleration in the identification of appropriate targets through the use of a parallel search. We also show that the formation of new branches in the vicinity of existing synapses leads to the formation of target connectivity with a decreased number of erroneous branches. This finding allows us to explain the high correlation between the branch points and synapses observed in the Xenopus laevis retinotectal system. We also suggest that the most efficient branching rule is different for axons and dendrites. The optimal axonal strategy is to form new branches in the vicinity of existing synapses, whereas the optimal rule for dendrites is to form new branches preferentially in the vicinity of synapses with correlated pre- and postsynaptic electric activity. Thus, our studies suggest that the developing neural system employs a set of sophisticated computational strategies that facilitate the formation of required circuitry, so that it may proceed in the fastest and most frugal way.