Figure 1. Recording multi‐unit activity across the spinal dorsal horn.

A, a 750 μm linear silicone array (16 electrodes, 50 μm spacing) was inserted vertically into L4/5 to a depth of approximately 900 μm to record from all sensory laminae. Cressyl violet stained section with electrode tract shown and overlay of electrode (to scale). Electrode represented schematically and laminar boundaries for the electrodes noted with dotted lines (superficial, intermediate and deep). B, following the removal of the dorsal aspect of the vertebrae and meninges the electrode was inserted into the cord where shown. C, stimulating electrodes were inserted under the proximal metatarsal pads so that the electrical stimulus occurred across the paw pad. D, example waveforms captured after cutaneous electrical stimulation using a 10% threshold (flat purple line). Window width and height is 1400 μs and 1500 μV, respectively. [Color figure can be viewed at wileyonlinelibrary.com]