Why decussate? Topological constraints on 3D wiring

Anat Rec (Hoboken). 2008 Oct;291(10):1278-92. doi: 10.1002/ar.20731.


Many vertebrate motor and sensory systems "decussate" or cross the midline to the opposite side of the body. The successful crossing of millions of axons during development requires a complex of tightly controlled regulatory processes. Because these processes have evolved in many distinct systems and organisms, it seems reasonable to presume that decussation confers a significant functional advantage--yet if this is so, the nature of this advantage is not understood. In this article, we examine constraints imposed by topology on the ways that a three-dimensional processor and environment can be wired together in a continuous, somatotopic, way. We show that as the number of wiring connections grows, decussated arrangements become overwhelmingly more robust against wiring errors than seemingly simpler same-sided wiring schemes. These results provide a predictive approach for understanding how 3D networks must be wired if they are to be robust, and therefore have implications both for future large-scale computational networks and for complex biomedical devices.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Animals
  • Biomedical Engineering*
  • Central Nervous System / anatomy & histology
  • Humans
  • Models, Neurological
  • Nerve Net / anatomy & histology*
  • Neural Networks, Computer*