The transfer characteristics of hair cells encoding mechanical stimuli in the lateral line of zebrafish

Pichler, P., Lagnado, L.
The Journal of neuroscience : the official journal of the Society for Neuroscience   39(1): 112-124 (Journal)
Registered Authors
Lagnado, Leon, Pichler, Paul
MeSH Terms
  • Animals
  • Female
  • Glutamic Acid/physiology
  • Image Processing, Computer-Assisted
  • Larva
  • Lateral Line System/cytology
  • Lateral Line System/physiology*
  • Male
  • Mechanoreceptors/physiology*
  • Motion Perception/physiology
  • Neuroimaging
  • Physical Stimulation*
  • Sensory Receptor Cells/physiology*
  • Synapses/physiology
  • Zebrafish/physiology*
30413644 Full text @ J. Neurosci.
Hair cells transmit mechanical information by converting deflection of the hair bundle into synaptic release of glutamate. We have investigated this process in the lateral line of larval zebrafish (male and female) to understand how mechanical stimuli are encoded within a neuromast. Using multiphoton microscopy in vivo, we imaged synaptic release of glutamate using the reporter iGluSnFR and deflections of the cupula. We found that the neuromast is composed of a functionally diverse population of hair cells. Half the hair cells signalled cupula motion in both directions from rest, either by increasing glutamate release in response to a deflection in the positive direction or by reducing release in the negative direction. The relationship between cupula deflection and glutamate release demonstrated maximum sensitivity at displacements of just ∼40 nm in the positive direction. The remaining hair cells only signalled motion in one direction and were less sensitive, extending the operating range of the neuromast beyond 1 μm. Adaptation of the synaptic output was also heterogeneous, with some hair cells generating sustained glutamate release in response to a steady deflection of the cupula and others generating transient outputs. Finally, a distinct signal encoded a return of the cupula to rest: a large and transient burst of glutamate release from hair cells unresponsive to the initial stimulus. A population of hair cells with these different sensitivities, operating ranges and adaptive properties will allow the neuromast to encode weak stimuli while maintaining the dynamic range to signal the amplitude and duration of stronger deflections.
SIGNIFICANCE STATEMENT Hair cells transmit information about mechanical stimuli by converting very small deflections of their hair bundle into changes in the release of the neurotransmitter glutamate. We have measured this input-output relation in the live fish using a fluorescent protein and find that different hair cells vary in their mechanical sensitivity and the time-course of their response. These variations will allow the fish to sense the timing and duration of both very weak stimuli (∼40 nm deflections) and strong stimuli (∼1 μm), underlying the ability of the fish to avoid predators and maintain its body position in flowing water.
Genes / Markers
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Engineered Foreign Genes