Figure 4.

Avoidance extinction in the IntelliCage in young and aged C57BL6/J and progranulin deficient (Grn^−/−) mice. (A) Illustration of the avoidance acquisition and extinction tasks. Red circles indicate nosepokes where air-puff punishments were applied and water access was blocked. White circles show free water access. (B,C) Time courses of nosepoke error percentages (mean ± s.e.m) per day in C57BL6/J (B) and progranulin deficient (Grn^−/−) mice (C); n = 8 per group. Time “0” shows the error proportion achieved during the 24 h acquisition period (mean over 24 h). rm-ANOVAs revealed significant differences between groups. SNI-treated aged mice of both genotypes showed the lowest error rates, P < 0.05. Asterisks denote time points which differed significantly vs. sham treated young mice, which were used as the reference group (P < 0.05, Dunnett post hoc). (D,E) Cumulative nosepoke error rates over time in young and aged mice during avoidance extinction. The step-wise day-to-day increase is due to preferred drinking times in the morning. All events of the group were combined and plotted according to Kaplan Meier curves. Each vertical line is an error and the horizontal lines indicate the percent error estimates of the respective groups. Aged mice of both genotypes showed the lowest nosepoke error rates i.e., the strongest retention of the aversive memory.