Fig. 4.

Analysis of high-responder populations in Kal7^KO mice. The distribution of total levels of responding for cocaine among mice was analyzed. (A) Histogram showing the fraction of each genotype earning a set number of infusions. A group of very high–level responders is observed for the Kal7^KO mice but not for the Wt mice. (B) Cumulative frequency plot of the data from A demonstrates the expected right-shift in the Kal7^KO curve. Kolmogorov-Smirnov analysis indicates that the shift does not reach statistical significance (P = 0.33). Histogram (C) and Kolmogorov-Smirnov (D) plots for 0.25-mg/kg/infusion data. A right-shift (higher responding) for the Kal7^KO mice is apparent on both the histogram and cumulative frequency plots. At this dose, Kolmogorov-Smirnov analysis shows a statistically significant difference between genotypes (**P = 0.039).