Figure 2.

Retrieval-conditioning strengthens contextual fear memory more reliably than other combinations of experiences. A, With a 15 min interval, both retrieval-conditioning and conditioning-retrieval show greater strengthening than retrieval-retrieval. B, With a 1 h interval, retrieval-conditioning strengthened contextual fear to a greater degree than conditioning-retrieval, and to an equivalent degree as double conditioning. C, D, Conditioning-retrieval with a 1 h interval did not upregulate Zif268 expression as assessed with Western blots (C) and flow cytometry (D). Data are presented as the mean + SEM.