Circuits That Mediate Expression of Signaled Active Avoidance Converge in the Pedunculopontine Tegmentum

J Neurosci. 2019 Jun 5;39(23):4576-4594. doi: 10.1523/JNEUROSCI.0049-19.2019. Epub 2019 Apr 1.


An innocuous sensory stimulus that reliably signals an upcoming aversive event can be conditioned to elicit locomotion to a safe location before the aversive outcome ensues. The neural circuits that mediate the expression of this signaled locomotor action, known as signaled active avoidance, have not been identified. While exploring sensorimotor midbrain circuits in mice of either sex, we found that excitation of GABAergic cells in the substantia nigra pars reticulata blocks signaled active avoidance by inhibiting cells in the pedunculopontine tegmental nucleus (PPT), not by inhibiting cells in the superior colliculus or thalamus. Direct inhibition of putative-glutamatergic PPT cells, excitation of GABAergic PPT cells, or excitation of GABAergic afferents in PPT, abolish signaled active avoidance. Conversely, excitation of putative-glutamatergic PPT cells, or inhibition of GABAergic PPT cells, can be tuned to drive avoidance responses. The PPT is an essential junction for the expression of signaled active avoidance gated by nigral and other synaptic afferents.SIGNIFICANCE STATEMENT When a harmful situation is signaled by a sensory stimulus (e.g., street light), subjects typically learn to respond with active or passive avoidance responses that circumvent the threat. During signaled active avoidance behavior, subjects move away to avoid a threat signaled by a preceding innocuous stimulus. We identified a part of the midbrain essential to process the signal and avoid the threat. Inhibition of neurons in this area eliminates avoidance responses to the signal but preserves escape responses caused by presentation of the threat. The results highlight an essential part of the neural circuits that mediate signaled active avoidance behavior.

Publication types

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

MeSH terms

  • Animals
  • Avoidance Learning / drug effects
  • Avoidance Learning / physiology*
  • Avoidance Learning / radiation effects
  • Brain Mapping
  • Carrier Proteins / genetics
  • Carrier Proteins / radiation effects
  • Clozapine / analogs & derivatives
  • Clozapine / pharmacology
  • Conditioning, Classical
  • Dependovirus / genetics
  • Drinking Behavior
  • Electroshock
  • Escape Reaction / drug effects
  • Escape Reaction / physiology*
  • Escape Reaction / radiation effects
  • GABAergic Neurons / physiology*
  • Gain of Function Mutation
  • Genes, Reporter
  • Genetic Vectors / administration & dosage
  • Light
  • Mice
  • Nerve Net / physiology*
  • Noise / adverse effects
  • Optogenetics
  • Pars Reticulata / cytology
  • Pars Reticulata / physiology*
  • Pedunculopontine Tegmental Nucleus / physiology*
  • Reaction Time
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / radiation effects
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / radiation effects
  • Superior Colliculi / cytology
  • Superior Colliculi / physiology
  • Thalamus / cytology
  • Thalamus / physiology


  • Carrier Proteins
  • Receptors, G-Protein-Coupled
  • Recombinant Fusion Proteins
  • channelopsin-2, Chlamydomonas reinhardtii
  • Clozapine
  • clozapine N-oxide