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. 2018 Jan 8;11:259. doi: 10.3389/fnbeh.2017.00259

Figure 1.

Figure 1

Effects of the RE procedure on recent and remote fear memories. (A) Schema of the experimental protocol. Animals were trained for contextual fear conditioning. They were then divided into two groups: one was for recent fear memory (n = 10) and the other for remote fear memory (n = 7). Two or 36 days later, the animals were subjected to the RE procedure. One day after RE, they received the extinction memory test (T1), reinstatement shock (RS), and the reinstatement test (T2) 24 h apart. (B) Freezing during the fear training session was comparable between the two groups. All rats acquired conditioned contextual fear as they received three footshocks. (C) Freezing during RE procedure. All rats showed significant fear attenuation within the extinction session. There were no significant freezing differences between the two groups during retrieval and extinction. (D) Fear levels for T1 and T2. The recent memory group showed similar freezing between T1 and T2, suggesting no reinstatement of fear. The remote memory group showed significant reinstatement of fear. Data are expressed as mean ± SEM. n.s., not significant, **P < 0.01.