Lesions of periaqueductal gray dissociate-conditioned freezing from conditioned suppression behavior in rats

Prin Amorapanth, Karim Nader, Joseph E. Ledoux

Research output: Contribution to journalArticle


It is commonly assumed that suppression of an ongoing behavior is an indirect measure of freezing behavior. We tested whether conditioned suppression and freezing are the same or distinct conditioned responses. Rats were trained to press a bar for food and then given fear-conditioning sessions in which a tone was paired with a foot shock (two pairings a day for 2 days). They then received either sham or electrolytic lesions of the periaqueductal gray (PAG). Post-training PAG lesions blocked freezing to the conditioned stimulus (CS), but had no effect on the suppression of operant behavior to the same CS. Thus, conditioned suppression and freezing, which both cause a cessation in activity, appear to be mediated by separate processes.

Original languageEnglish (US)
Pages (from-to)491-499
Number of pages9
JournalLearning and Memory
Issue number5
StatePublished - Nov 8 1999


ASJC Scopus subject areas

  • Neuropsychology and Physiological Psychology
  • Cognitive Neuroscience
  • Cellular and Molecular Neuroscience

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