Figure 5.
Restoration of spatially defined activity in the dorsal horn after spared-root lesion and chondroitinase ABC treatment. A–I, Field potential recordings were made from 12 sites (surface of gray matter and descending in 100 μm steps) along a track 400 μm lateral to the midline, 7, 14, and 28 d after sham, spared-root, and saline or ChABC treatment. Three-dimensional reconstructions of field potential recordings (A, B, D, E, G, H) illustrate activity changes (color coded; 0.5 mV, red, to −4.0 mV, indigo) recorded at different depths (x-axis) in spinal gray matter after electrical stimulation of the C7 dorsal root (time, z-axis). Contralateral spinal cords from sham-lesioned (A), lesion- and vehicle-treated (D), and lesion- and ChABC-treated (G) animals illustrate equivalent activity profiles. The peak amplitude of the N-wave and latency of N-wave recorded from contralateral spinal cords were not significantly different between groups at any time point after lesion. Lesioned animals that received saline treatment illustrated significantly reduced activity ipsilateral to the lesion (E; original trace shown in F, J) (*p < 0.05, ANOVA) compared with sham-lesioned animals (B; original trace, C) at all time points after lesion (J). The latency of the N-wave was significantly elevated in saline-treated animals compared with sham-lesioned animals at all postlesion time points (K) (*p < 0.05, ANOVA). In contrast, lesioned animals that received ChABC treatment illustrated robust activity in the dorsal horn ipsilateral to the lesion (H; original trace, I). Assessment of the peak amplitude of N-wave showed that it was not significantly reduced compared with sham-lesioned animals at 7 and 14 d after lesion (J) and was significantly higher than saline-treated animals at all postinjury time points (J) (#p < 0.01, ANOVA). The latency of the N-wave from ChABC-treated animals was significantly reduced compared with saline-treated animals (K) (#p ≤ 0.05, ANOVA), but not significantly different from sham-lesioned animals (K). Error bars indicate SEM.