FIGURE 4.

Effect of peripheral electrical stimulation on the WDR cell response. (A) Experimental set-up design illustrating the site of electrophysiological recording of WDR cells at spinal L2-L4 segments, and the location, in the ipsilateral paw of the electrical stimulation applied to the receptive field (RF). (B) Raw data of twenty stimulus artifacts and (C) raw data of consecutive WDR responses to RF stimulation in two different cells (Cell 1 and Cell 2). (D) shows the raw tracing of a single second-order WDR neuron cluster response induced by one electrical stimulus-evoked in Cell 1 (left) or Cell 2 (right). (E) shows the raster plot and (F) peri-stimulus time histograms (PSTH) constructed from twenty WDR neuronal responses to RF stimulation depicting the different fiber components (Aβ-, Aδ-, C-fibers, and post-discharge). Note that, under our experimental condition, no clear wind-up is elicited. (G) shows that the basal response, i.e., the total of action potentials evoked at t = 0 in the different experimental groups, is not statistically different (χ² = 4.535; p = 0.605).