Figure 4
Decay of retention levels during extinction.
Extinction tests were conducted with the same CS+ used during phase 2 of training and a fixed CS− (common to all groups) with very low similarity against the CS+ (SSIM = 0.04) in the absence of reinforcement (i.e. the submerged platform was removed; see Methods). (A–C) Group average values of the retention index as a function of the extinction trials. The decay was approximated by a mono-exponential process (continuous lines). Number of mice per group in parentheses. (D) Mono-exponential curves were non-linear fit to the data from individual mice and their decay-times compared across groups. Note the apparently slower decay in the retention index obtained with SSIMdec,narrow compared to SSIM = 0.04. Asterisks denote differences between groups (unpaired t test, *P < 0.05).
