ZFIN ID: ZDB-PUB-110628-40
Visual system scaling in teleost fish
Bakken, T.E., and Stevens, C.F.
Date: 2012
Source: The Journal of comparative neurology   520(1): 142-53 (Journal)
Registered Authors: Stevens, Craig
Keywords: scaling, visual system, retinal ganglion cells, conduction delay, teleost fish
MeSH Terms:
  • Animals
  • Axons/physiology
  • Axons/ultrastructure
  • Goldfish*/anatomy & histology
  • Goldfish*/growth & development
  • Neural Conduction/physiology
  • Optic Nerve/physiology
  • Optic Nerve/ultrastructure
  • Retinal Ganglion Cells/cytology
  • Superior Colliculi/anatomy & histology
  • Superior Colliculi/physiology
  • Visual Pathways*/anatomy & histology
  • Visual Pathways*/physiology
  • Zebrafish*/anatomy & histology
  • Zebrafish*/growth & development
PubMed: 21681750 Full text @ J. Comp. Neurol.
Teleost fish grow continuously throughout their lifespan, and this growth includes visual system components: eyes, optic nerves, and brain. As fish grow, the optic nerve lengthens and neural signals must travel increasing distances from the eye to the optic tectum along thousands of retinal ganglion cell (RGC) axons. Larger fish have better vision that enhances their ability to capture prey, but they are faced with the potential computational problem of changes in the relative timing of visual information arriving at the brain. Optic nerve conduction delays depend on RGC axon conduction velocities, and velocity is primarily determined by axon diameters. If axon diameters do not increase in proportion to body length, then absolute and relative conduction delays will vary with fish size. We have measured optic nerve lengths and axon diameter distributions in different sized zebrafish (Danio rerio) and goldfish (Carassius auratus) and find that, as both species of fish grow, axon diameters increase to reduce average conduction delays by about half and to keep relative delays constant. This invariance of relative conduction delays simplifies computational problems faced by the optic tectum.