Fig. 5.

An example of original recordings of neurons in the rostral ventromedial medulla of an animal with neuropathic hypersensitivity. I: the temperature of the contact stimulator (baseline 35°C, peak 53°C) applied to the left (nerve injured) hind limb. II: withdrawal of the stimulated hind limb as assessed by a piezoelectric device. III: raw data of neuronal recordings (due to long time scale and high discharge frequency; the consecutive spikes are adjacent to each other). IV: peristimulus time histograms of an OFF-cell discharge. V: peristimulus time histogram of an ON-cell discharge. Templates of the simultaneously recorded OFF- and ON-neuron are shown above the peristimulus time histograms. Graphs in the left column show recording before S2 stimulation (Pre-), and graphs in the middle column show recording during S2 stimulation (the horizontal bar above the stimulus temperature trace represents 15 s, and it indicates the duration of S2 stimulation at the intensity of 30 µA; note the S2 stimulation-induced electric noise that masks concurrent neuronal recordings). The graphs in the right column show recording 2 min after the end of the ascending series of S2 stimulations (Post-). S2 stimuli were applied at 2-min intervals at the intensity of 30 µA (shown), 50 µA (not shown), and 70 µA (not shown).