Abstract
During nervous system development growing axons can interact with each other, for example by adhering together in order to produce bundles (fasciculation). How does such axon-axon interaction affect the resulting axonal trajectories, and what are the possible benefits of this process in terms of network function? In this paper we study these questions by adapting an existing computational model of the development of neurons in the Xenopus tadpole spinal cord to include interactions between axons. We demonstrate that even relatively weak attraction causes bundles to appear, while if axons weakly repulse each other their trajectories diverge such that they fill the available space. We show how fasciculation can help to ensure axons grow in the correct location for proper network formation when normal growth barriers contain gaps, and use a functional spiking model to show that fasciculation allows the network to generate reliable swimming behaviour even when overall synapse counts are artificially lowered. Although we study fasciculation in one particular organism, our approach to modelling axon growth is general and can be widely applied to study other nervous systems.
Highlights
In this paper we describe a computational model of the anatomy and functionality of neuronal networks in the spinal cord of the hatchling Xenopus laevis tadpole
In Xenopus laevis, loss of the Neural Cell Adhesion Molecule (NCAM) that is expressed by sensory Rohon-Beard (RB) neurons causes a reduction in the RB population and its absence from the dorsolateral tract[7]
We present the results of simulations of the growth and functional models
Summary
During nervous system development growing axons can interact with each other, for example by adhering together in order to produce bundles (fasciculation). It is known experimentally that trunk skin stimulation causes the neuronal circuits in the spinal cord to generate a pattern of spiking activity that corresponds to swimming, with left-right alternating motoneuron spikes at 10–25 Hz. The developmental process of axon growth and synapse formation generates connectomes which have specific properties that support swimming initiation. In14 fasciculation is modelled as a culmination of short and long range attractive cues, while in[15] attractive short-range interactions between axons of different types (referring to axons which express different levels of adhesion proteins in their membranes) are considered These models were used to investigate the likely mechanisms that influence fasciculation and the physical dynamics of the process.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
