Figure 3

The increase in presynaptic excitation in the spinal dorsal horn by picrotoxin. A, Spatially averaged time course of the optical response elicited by a high-intensity single-pulse stimulation to the dorsal root in a slice stained anterogradely with a voltage-sensitive dye applied to the dorsal root (thin line), and the time course obtained from the same slice after bath application of the voltage-sensitive dye (thick line). These spatially averaged time courses were obtained in 16 × 16 pixels in the substantia gelatinosa. B, Spatially averaged time courses of optical responses in slices stained anterogradely with a voltage-sensitive dye. The upper and lower traces indicate the responses in the substantia gelatinosa of spinal dorsal horn by a high and a low-intensity stimulation in control (thin line) and picrotoxin (thick line) conditions, respectively. C, The bar graph summarizes the picrotoxin-induced increases in the net neuronal excitation (net), presynaptic excitation (pre).