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. Author manuscript; available in PMC: 2011 Jan 5.
Published in final edited form as: Behav Brain Res. 2009 Sep 9;206(1):127–134. doi: 10.1016/j.bbr.2009.09.007

Figure 2.

Figure 2

Heart rate (HR) conditioning to the tone conditioned stimulus (CS) was established in all groups and subsequently extinguished by CS- alone and unpaired CS and unconditioned stimulus (US) presentations. Data are shown as mean change (± SEM) in inter-beat interval (IBI) from baseline to the CS during CS-alone habituation trials, CS-alone probe trials on Day1 and Day2 of HR conditioning, extinction days 1-3 of HR extinction, and the first 10 and last 10 trials of the CS Test. For HR extinction, data pictured are only from groups receiving CS presentations during extinction, including the CS-alone probes from the group receiving continued CS-US pairings (PD, open box, n=10) and CS-alone presentations from the CS-alone extinction group (CS Ext, open triangle, n=12) and unpaired CS/US extinction group (UP Ext, black box, n=12). Other abbreviations: US-alone extinction (US Ext, open circle, n=12), sit control group remaining in home cages (Sit, black circle, n=12). Asterisks indicate significant differences between groups at p < 0.05.