A Spike-Timing Mechanism for Action Selection

Nat Neurosci. 2014 Jul;17(7):962-70. doi: 10.1038/nn.3741. Epub 2014 Jun 8.


We discovered a bimodal behavior in the genetically tractable organism Drosophila melanogaster that allowed us to directly probe the neural mechanisms of an action selection process. When confronted by a predator-mimicking looming stimulus, a fly responds with either a long-duration escape behavior sequence that initiates stable flight or a distinct, short-duration sequence that sacrifices flight stability for speed. Intracellular recording of the descending giant fiber (GF) interneuron during head-fixed escape revealed that GF spike timing relative to parallel circuits for escape actions determined which of the two behavioral responses was elicited. The process was well described by a simple model in which the GF circuit has a higher activation threshold than the parallel circuits, but can override ongoing behavior to force a short takeoff. Our findings suggest a neural mechanism for action selection in which relative activation timing of parallel circuits creates the appropriate motor output.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Animals
  • Behavior, Animal / physiology*
  • Calcium Signaling / physiology
  • Drosophila melanogaster / physiology*
  • Electrophysiological Phenomena / physiology
  • Escape Reaction / physiology
  • Female
  • Flight, Animal / physiology
  • Immunohistochemistry
  • Models, Neurological
  • Models, Psychological
  • Nerve Net / physiology
  • Odonata
  • Photic Stimulation
  • Predatory Behavior
  • Video Recording