Controlled cortical impact before or after fear conditioning does not affect fear extinction in mice

Demetrio Sierra-Mercado, Lauren M. McAllister, Christopher C.H. Lee, Mohammed R. Milad, Emad N. Eskandar, Michael J. Whalen

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Post-traumatic stress disorder (PTSD) is characterized in part by impaired extinction of conditioned fear. Traumatic brain injury (TBI) is thought to be a risk factor for development of PTSD. We tested the hypothesis that controlled cortical impact (CCI) would impair extinction of fear learned by Pavlovian conditioning, in mice. To mimic the scenarios in which TBI occurs prior to or after exposure to an aversive event, severe CCI was delivered to the left parietal cortex at one of two time points: (1) Prior to fear conditioning, or (2) after conditioning. Delay auditory conditioning was achieved by pairing a tone with a foot shock in "context A". Extinction training involved the presentation of tones in a different context (context B) in the absence of foot shock. Test for extinction memory was achieved by presentation of additional tones alone in context B over the following two days. In pre- or post-injury paradigms, CCI did not influence fear learning and extinction. Furthermore, CCI did not affect locomotor activity or elevated plus maze testing. Our results demonstrate that, within the time frame studied, CCI does not impair the acquisition and expression of conditioned fear or extinction memory.

Original languageEnglish (US)
Pages (from-to)133-141
Number of pages9
JournalBrain research
StatePublished - May 5 2015
Externally publishedYes


  • Anxiety disorder
  • Dorsal hippocampus
  • Extinction
  • Fear learning
  • Learning and memory
  • Rodent
  • Traumatic brain injury

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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