Transient inhibition and long-term facilitation of locomotion by phasic optogenetic activation of serotonin neurons

Elife. 2017 Feb 14;6:e20975. doi: 10.7554/eLife.20975.

Abstract

Serotonin (5-HT) is associated with mood and motivation but the function of endogenous 5-HT remains controversial. Here, we studied the impact of phasic optogenetic activation of 5-HT neurons in mice over time scales from seconds to weeks. We found that activating dorsal raphe nucleus (DRN) 5-HT neurons induced a strong suppression of spontaneous locomotor behavior in the open field with rapid kinetics (onset ≤1 s). Inhibition of locomotion was independent of measures of anxiety or motor impairment and could be overcome by strong motivational drive. Repetitive place-contingent pairing of activation caused neither place preference nor aversion. However, repeated 15 min daily stimulation caused a persistent increase in spontaneous locomotion to emerge over three weeks. These results show that 5-HT transients have strong and opposing short and long-term effects on motor behavior that appear to arise from effects on the underlying factors that motivate actions.

Keywords: dorsal raphe nucleus; locomotion; mouse; neuroscience; optogenetics; serotonin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anxiety
  • Dorsal Raphe Nucleus / physiology*
  • Locomotion*
  • Mice
  • Motivation
  • Neural Inhibition*
  • Neurons / physiology*
  • Optogenetics
  • Serotonin / metabolism*
  • Serotonin Receptor Agonists

Substances

  • Serotonin Receptor Agonists
  • Serotonin