ZFIN ID: ZDB-PUB-150106-13
The influence of activity on axon pathfinding in the optic tectum
Kita, E.M., Scott, E.K., Goodhill, G.J.
Date: 2015
Source: Developmental Neurobiology   75(6): 608-20 (Journal)
Registered Authors: Scott, Ethan
Keywords: TTX, axon pathfinding, neural development, retinal ganglion cell, tectum, time-lapse, topographic maps, zebrafish
MeSH Terms:
  • Animals
  • Animals, Genetically Modified
  • Axons/drug effects
  • Axons/physiology*
  • Basic Helix-Loop-Helix Transcription Factors/genetics
  • Basic Helix-Loop-Helix Transcription Factors/metabolism
  • Body Patterning/drug effects
  • Body Patterning/physiology*
  • DNA-Binding Proteins/genetics
  • DNA-Binding Proteins/metabolism
  • Embryo, Nonmammalian
  • Green Fluorescent Proteins/genetics
  • Green Fluorescent Proteins/metabolism
  • Larva
  • Neurons/cytology
  • Neurons/drug effects
  • Neurons/physiology*
  • Sodium Channel Blockers/pharmacology
  • Superior Colliculi*/cytology
  • Superior Colliculi*/embryology
  • Superior Colliculi*/growth & development
  • Tetrodotoxin/pharmacology
  • Transcription Factor Brn-3/genetics
  • Transcription Factor Brn-3/metabolism
  • Transcription Factors/genetics
  • Transcription Factors/metabolism
  • Visual Pathways/drug effects
  • Visual Pathways/embryology*
  • Visual Pathways/growth & development*
  • Zebrafish
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism
PubMed: 25556913 Full text @ Dev. Neurobiol.
The relative importance of neural activity versus activity-independent cues in shaping the initial wiring of the brain is still largely an open question. While activity is clearly critical for circuit rearrangements after initial connections have been made, whether it also plays a role in initial axon pathfinding remains to be determined. Here we investigated this question using the guidance of zebrafish retinal ganglion cell axons to their targets in the tectum as a model. Recent results have implicated biased branching as a key feature of pathfinding in the zebrafish tectum. Using tetrodotoxin to silence neural activity globally, we found a decrease in the area covered by axon branches during pathfinding. After reaching the target, there were dynamic differences in axon length, area and the number of branches between conditions. However other aspects of pathfinding were unaffected by silencing, including the ratio of branches directed towards the target, length, and number of branches, as well as turning angle, velocity, and number of growth cones per axon. These results challenge the hypothesis that neural connections develop in sequential stages of molecularly guided pathfinding and activity-based refinement. Despite a maintenance of overall guidance, axon pathfinding dynamics can nevertheless be altered by activity loss. This article is protected by copyright. All rights reserved.