Figure 1

Head-withdrawal latency to Glu or vehicle (Veh) injection into the tongue or whisker pad skin, head-withdrawal threshold to heat or cold stimulation of the tongue or whisker pad skin in the rats with Glu or Veh injection into the tongue or whisker pad skin. The onset latency of EMG activity was recorded from the splenius capitis muscle following Glu or Veh injection into the tongue or whisker pad skin, and the head-withdrawal threshold to heat or cold stimulation of the tongue or whisker pad skin was also measured as the suprathreshold stimulus intensity evoking EMG activity. A: Mean head-withdrawal latency following Glu or Veh injection into the tongue or whisker pad skin, B and C: Mean head-withdrawal threshold following heat or cold stimulation of the tongue or whisker pad skin in the rat with Glu or Veh injection, respectively. Inset diagrams in each panel indicate EMG activities recorded from the splenius capitis muscle following Glu injection into the whisker pad skin (A), that following heat or cold stimulation of the whisker pad skin in the Glu injected rat (B and C). The head-withdrawal threshold to heat or cold stimulation of the tongue contralateral side in the rats with Glu or Veh injection into the tongue (D) and heat stimulation of the whisker pad skin contralateral side in the rats with Glu or Veh injection into the whisker pad skin (E). *: p < 0.05, **: p < 0.01.