Fig. 4

Effects of arthritis on temperature preference (experiment 3). a Test time-dependent changes in the preference ratio between two plates with fixed temperature (25 °C) and increasing temperature (1 °C/min from 25 °C for 24 min) in the pre-clinical period (days 19–24), early clinical period (days 28–33), and late clinical period (days 38–42) in the saline, CFA, and CIA groups. Ordinate, preference ratio per 2 min; abscissa, test time. The color scale above indicates the temperature of the plate at each time point. The test interval was divided in three phases as follows: 0–6 min, phase I; 6–18 min, phase II; and 18–24 min, phase III. The horizontal dotted line indicates a preference ratio of 0.5. b Time course of the mean preference ratio in each phase in the saline, CFA, and CIA groups. The horizontal dotted line indicates a preference ratio of 0.5. The values in a and b are shown as the mean ± standard error of the mean. *p < 0.05, **p < 0.01, saline vs. CIA; ^#p < 0.05, ^##p < 0.01, CFA vs. CIA, by one-way ANOVA followed by Tukey’s test. c Time course of arthritis score (upper y axis) and preference ratio in phase II (lower y axis) in the CIA group. d₁ Scatter plots showing the relationship between the preference ratio in phase II (y axis) and arthritis score (x axis) on days 28 (above) and 38 (below). The insets show the values for Kendall’s tau and the p value for zero correlation. d₂ Time course of rank correlation coefficient for the relationship between the preference ratio in phase II and the arthritis score in the CIA group. The hashed zone indicates the 95% confidence interval for Kendall’s tau. *p < 0.05, **p < 0.01, by Kendall’s correlation analysis. ANOVA, analysis of variance; CFA, complete Freund’s adjuvant; CIA, collagen-induced arthritis