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. Author manuscript; available in PMC: 2011 Aug 1.
Published in final edited form as: Behav Neurosci. 2010 Aug;124(4):510–519. doi: 10.1037/a0020083

Figure 2.

Figure 2

Fear acquisition. Animals were trained under the influence of naltrexone or the saline vehicle. Mean (+/− SEM ) percent freezing to each respective CS during eight trials of conditioning is shown. Data collapsed across the type of CS that was used for conditioning reveals no significant overall effect of drug on acquisition (A). Although there was a significant effect of CS-type, all animals showed significant fear acquisition regardless of whether they were trained with the Light CS (B), the Light-Noise compound CS (C) or without any discrete CS (D). Acquisition for each respective CS was not significantly different for animals trained under saline compared to naltrexone.