The basal responsiveness of spinal cords from L1 mice is increased. Comparison of ventral root responses to dorsal root stimulation obtained from wild type (wt) (n = 10) and L1 (n = 11) mice. (A) The intensity-response curve shows the number of spikes elicited by single stimuli of increasing intensities. Responses in L1 mice were larger (overall ANOVA, P < 0.01). (B) The wind-up curve shows number of spikes in ventral root recordings to trains of stimuli at C-fibre intensity (1 Hz). Responses in L1 mice were greater (overall ANOVA, P < 0.001). (C) Comparison of the conduction velocity in A- and C-fibers in wild type (wt) and L1 mice.