In Vivo Ca(2+) Imaging Reveals that Decreased Dendritic Excitability Drives Startle Habituation

Cell Rep. 2015 Dec 1;13(9):1733-40. doi: 10.1016/j.celrep.2015.10.060. Epub 2015 Nov 19.


Exposure to repetitive startling stimuli induces habitation, a simple form of learning. Despite its simplicity, the precise cellular mechanisms by which repeated stimulation converts a robust behavioral response to behavioral indifference are unclear. Here, we use head-restrained zebrafish larvae to monitor subcellular Ca(2+) dynamics in Mauthner neurons, the startle command neurons, during startle habituation in vivo. Using the Ca(2+) reporter GCaMP6s, we find that the amplitude of Ca(2+) signals in the lateral dendrite of the Mauthner neuron determines startle probability and that depression of this dendritic activity rather than downstream inhibition mediates glycine and N-methyl-D-aspartate (NMDA)-receptor-dependent short-term habituation. Combined, our results suggest a model for habituation learning in which increased inhibitory drive from feedforward inhibitory neurons combined with decreased excitatory input from auditory afferents decreases dendritic and Mauthner neuron excitability.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Calcium Signaling / drug effects
  • Dendrites / metabolism*
  • Dizocilpine Maleate / pharmacology
  • Larva / metabolism
  • Neuronal Calcium-Sensor Proteins / metabolism
  • Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors
  • Receptors, N-Methyl-D-Aspartate / metabolism
  • Reflex, Startle / drug effects
  • Strychnine / pharmacology
  • Zebrafish / growth & development
  • Zebrafish / metabolism


  • Neuronal Calcium-Sensor Proteins
  • Receptors, N-Methyl-D-Aspartate
  • Dizocilpine Maleate
  • Strychnine
  • Calcium