Integration of Swimming-Related Synaptic Excitation and Inhibition by olig21 Eurydendroid Neurons in Larval Zebrafish Cerebellum

Thomas C. Harmon, David L. McLean, Indira M. Raman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


The cerebellum influences motor control through Purkinje target neurons, which transmit cerebellar output. Such output is required, for instance, for larval zebrafish to learn conditioned fictive swimming. The output cells, called eurydendroid neurons (ENs) in teleost fish, are inhibited by Purkinje cells and excited by parallel fibers. Here, we investigated the electrophysiological properties of glutamatergic ENs labeled by the transcription factor olig2. Action potential firing and synaptic responses were recorded in current clamp and voltage clamp from olig21 neurons in immobilized larval zebrafish (before sexual differentiation) and were correlated with motor behavior by simultaneous recording of fictive swimming. In the absence of swimming, olig21 ENs had basal firing rates near 8 spikes/s, and EPSCs and IPSCs were evident. Comparing Purkinje firing rates and eurydendroid IPSC rates indicated that 1-3 Purkinje cells converge onto each EN. Optogenetically suppressing Purkinje simple spikes, while preserving complex spikes, suggested that eurydendroid IPSC size depended on presynaptic spike duration rather than amplitude. During swimming, EPSC and IPSC rates increased. Total excitatory and inhibitory currents during sensory-evoked swimming were both more than double those during spontaneous swimming. During both spontaneous and sensory-evoked swimming, the total inhibitory current was more than threefold larger than the excitatory current. Firing rates of ENs nevertheless increased, suggesting that the relative timing of IPSCs and EPSCs may permit excitation to drive additional eurydendroid spikes. The data indicate that olig21 cells are ENs whose activity is modulated with locomotion, suiting them to participate in sensorimotor integration associated with cerebellum-dependent learning.

Original languageEnglish (US)
Pages (from-to)3063-3074
Number of pages12
JournalJournal of Neuroscience
Issue number15
StatePublished - Apr 8 2020


  • Cerebellar nuclei
  • Complex spike
  • IPSC
  • Locomotion
  • Parallel fiber
  • Purkinje cell

ASJC Scopus subject areas

  • Neuroscience(all)


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