Fig. 1.

Effect of spinal 5-HT₃ receptor inhibition on stimulus-evoked firing in the VPL of sham rats. WDR neuronal responses to punctate mechanical (A), heat (B), cold (C), and dynamic brush (D) stimuli, prior to and following spinal administration of ondansetron. Histogram traces represent typical single unit responses. Data represent mean ± 95% CI, n = 12 neurones from 8 rats. Asterisks (*) denote difference between baseline and 10 μg ondansetron, daggers (†) denote difference between baseline and 50 μg ondansetron, *P < 0.05, **P < 0.01. (Ac – acetone, Ec – ethyl chloride).