Central Plasticity of Cutaneous Afferents Is Associated with Nociceptive Hyperreflexia after Spinal Cord Injury in Rats

Figure 1

Wiring diagram of the cutaneus trunci muscle (CTM) reflex and CTM neurogram signal processing. (a) A lateral hemisection injury was made at the T10 spinal level on the right side of animals (purple box). CTM motor responses were evoked by electrical stimulations (Stim) given at each dorsal cutaneous nerve (DCN) level, above (T6 and T8) and below (T12 and L1) the level of injury (T10), of each side of rats 6 weeks after injury as well as in uninjured normal controls. In other groups of those normal and injured animals, axon tracers were injected to T7 and T13 DCNs: cholera toxin subunit B (CTB, green) for myelinated A fibers and isolectin B4 (IB4, red) for unmyelinated C fibers. DRG = dorsal root ganglion; aPSN = ascending propriospinal neuron; MN = motoneuron. (b) CTM neurograms were evoked at 5 mA that evokes both early and late responses mediated by Aδ and C fibers, respectively. Raw recording data were filtered, rectified, time-windowed for early (3.5–25.5 ms) and late (45.5-95.5 ms) responses from the stimulation onset. CTM responses were averaged across animals, smoothed, and color-scaled based on amplitudes (μV).

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