Figure 3

Neuronal activity changes in layer 5 (L5) of the primary motor cortex (M1) after spinal cord injury (SCI) with transcranial direct current stimulation (tDCS). (a) Experimental scheme. (b) GCaMP8f.-coded adeno-associated virus (AAV) was injected in L5 of M1. (c) Experimental scheme of tDCS. The anode was placed over the skull between the eyes, and the cathode was implanted in the neck. (d) Frequency of Ca²⁺ transients, power of Ca²⁺ transients, and correlation of paired neuronal activity on post-operation day 7 (POD7) in the tDCS− and tDCS+ sham-operated (Sham) groups (n = 5 mice per group). (e) Typical traces of Ca²⁺ transients at pre-operation (Pre), POD2, POD4, and POD7 in the tDCS + sham-operated group and (f) tDCS + SCI group. (g) Frequency of Ca²⁺ transients at Pre, POD2, POD4, and POD7 in the Sham tDCS + PLX− and SCI + tDCS + PLX− groups. (h) Power of Ca²⁺ transients (also see “Methods”) at Pre, POD2, POD4, and POD7 in the Sham tDCS + PLX− and SCI + tDCS + PLX− groups. (i) Standardized correlational changes in paired neurons at Pre, POD2, POD4, and POD7 in the Sham tDCS + PLX − and SCI + tDCS + PLX− groups. Each black circle represents the average data for an individual mouse (d and g–i). Data are shown as mean ± standard deviation (i). *p < 0.05 and ****p < 0.0001; tDCS− and tDCS+ sham groups were compared (d) and Sham tDCS + PLX− and SCI + tDCS + PLX− groups were compared for each day (g–i). Statistical analysis was performed using unpaired t-test (d) and one-way (g, h) or two-way (i) analysis of variance followed by Bonferroni post-hoc tests.