Effect of low dose capsaicin injection on the responses of a spinal dorsal horn neuron to mechanical stimuli. Rate histograms represent the responses to mechanical stimuli of a dorsal horn neuron before and following intradermal injection of capsaicin (0.1%, 10 μl). Top row: baseline background activity and responses to brush, press, and pinch; Second row: responses at 15 minutes after capsaicin injection. Third row: responses at 30 minutes after capsaicin injection. Fourth row: responses at 60 minutes after capsaicin injection.