Histograms showing mean neuronal activity. Activity was normalised to the baseline of 10 min periods (a) and of 30 min periods (b) in the MK-8825 group (grey bars, n = 12) and the vehicle group (black bars, n = 11); error bars are s.e.m. (c) Mean normalised activity (+ s.e.m.) of 6 units treated with nitroglycerin (GTN) alone for two hours. Significant differences in activity compared to the baseline periods (0–30 min) are indicated by a star and compared to periods after vehicle/MK-8825 infusion by #; repeated measures ANOVA and LSD post hoc test (a, b) or WILCOXON (c).