Behavioural Brain Research 238 (2013) 200–205 Contents lists available at SciVerse ScienceDirect Behavioural Brain Research j ourna l ho me pa ge: www.elsevier.com/locate/bbr Short communication Social modulation in extinction of aversive memories Aleksandra Nowak, Tomasz Werka, Ewelina Knapska ∗ Department of Neurophysiology, Nencki Institute of Experimental Biology, Polish Academy of Science, 3 Pasteur St., 02-093 Warsaw, Poland h i g h l i g h t s ◮ We propose two models of social modulation of extinction memory retrieval. ◮ Extinguished fear response renews in the presence of a fearful conspecific. ◮ Extinguished avoidance response renews in the presence of a fearful conspecific. a r t i c l e i n f o Article history: Received 13 June 2012 Received in revised form 16 October 2012 Accepted 18 October 2012 Available online 26 October 2012 Keywords: Fear conditioning Place avoidance Extinction Renewal Empathy Anxiety disorders a b s t r a c t Return of fear after extinction is a considerable challenge for the efficacy of exposure-based therapies. Fear recovery is most often modeled in the laboratory by changing the experimental context and studied in isolated animals. Since social context is an important factor affecting behavior, the question arises how it influences the recovery of extinguished fear. Here we present two novel behavioral models that allow studying social modulation of extinction memory retrieval. We show that the presence of a fearful cage mate results in a robust renewal of freezing as well as avoidance responses that were previously successfully extinguished. © 2012 Elsevier B.V. All rights reserved. Fear-eliciting properties of a stimulus acquired through con- ditioning can be extinguished by a repeated presentation of the conditioned stimulus (CS) in the absence of the unconditioned stim- ulus [1]. Similarly, extinction of learned place avoidance behavior occurs when visiting the place is no longer punished [2]. However, such extinction process does not reflect unlearning of the original association, but results in a transient inhibition of fear. For example, extinguished fear responses may return after a change of context (renewal phenomenon) [3]. In recent years, increased interest in mechanisms underlying fear extinction has emerged, partly because it is a useful model for exposure-based therapies for the treatment of human anxi- ety disorders, such as phobias and post-traumatic stress disorder [4]. The return of fear after extinction is a considerable challenge for maintaining long-lasting fear suppression after exposure-based therapies [5]. Until recently, the fear extinction and recovery phenomena were studied only in isolated animals. However, since vicarious experience accounts of both etiology and extinction of phobias have been shown in humans [6,7], social modulation seems ∗ Corresponding author. Tel.: +48 22 5892 257; fax: +48 22 5892 490. E-mail address: e.knapska@nencki.gov.pl (E. Knapska). to be an important factor that can affect the efficacy of exposure based therapies. Social modulation of fear and avoidance learning in animal models was shown before [8–11]; however until now there were no animal models allowing for studying vicarious modulation of aversive memories extinction. In the present study, we examined influence of a fearful conspecific’s presence on the rate of retrieval of fear and place avoidance extinction memory. In the first experiment we tested retrieval of fear extinction memory in the presence of a fearful conspecific. Male 2–3-month- old C57BL/6 male mice were housed in pairs, extensively handled for 3 weeks in order to minimize stress caused by an experimenter’s presence and habituated to transport to experimental room and to experimental cage (in three 10-min sessions). Then, the mice were subjected to fear conditioning and extinction in the Panlab shuttle-box for mice (LE918), which was divided by a perforated transparent partition allowing the mice to see, hear and smell the neighbor, but not to contact him physically. The mice were trained and tested in the left or right part of the shuttle-box cage (for every animal the side of the cage was the same through the whole behavioral procedure). Sensory stimuli were adjusted to generate two distinct contexts (context A: room lights on, the cage cleaned with a 1% acid solution, the mice transported to this context in 0166-4328/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.bbr.2012.10.031