Fig. 1. Time courses of the intensity (  top ) and duration (  bottom ) of  N -methyl-D-aspartate (NMDA)-induced pain-related behavior. NMDA was infused into the lumbar intrathecal space through a dialysis probe during 0–10 min. Data for the intensity and the duration of pain-related behavior are presented as median and 25th–75th percentiles (n = 6–9) and mean ± SD (n = 6–9), respectively. *Statistical significance among NMDA 0.1 mM, 1.0 mM, and 5.0 mM (  P < 0.01). Statistical analyses also indicated the significant differences among NMDA 0.1 mM, 1.0 mM, and 5.0 mM (  P < 0.01) in the intensity of the pain-related behavior.