Fig. 5: Depleting acetylcholine in the brain prevents the reversal of pathological plasticity and blocks motor and sensory recovery after nerve injury.

a Depletion of acetylcholine in rats that receive equivalent VNS paired with rehabilitation (ACh-:CL-VNS, n = 4) blocks the VNS-dependent restoration area of motor cortex evoking movements of the denervated digit flexors (CL-VNS, n = 4; Rehab, n = 4). Additionally, CL-VNS reverses the aberrant expansion of evoked extension movements, while acetylcholine-depleted subjects display an enduring expansion of extension representations. Compare to Fig. 2. b Bubble plots displaying the cortical locations of digit flexion and extension movements across all animals in each experimental group. The size of each bubble represents the proportion of subjects for which ICMS evoked digit flexion or extension movements at each cortical site. Note that depletion of acetylcholine prevents CL-VNS-dependent restoration of digit flexion representations and also prevents the reduction of extensor representations. Same group sizes as in a. c Consistent with blocking the reversal of pathological plasticity, depletion of acetylcholine prevents the VNS-dependent enhancement of recovery of motor function after nerve injury (Rehab, n = 9; CL-VNS, n = 9; ACh-:CL-VNS, n = 5). d ACh-:CL-VNS subjects exhibit substantially reduced levels of motor recovery compared to CL-VNS. Same group sizes as in c. e Depletion of acetylcholine also prevents VNS-dependent recovery of tactile thresholds (Rehab: n = 5; CL-VNS: n = 5; ACh-:CL-VNS: n = 5). Circles depict individual subjects in panels (a, e). In c asterisks indicate significant differences using t-tests across groups at each time point, and the color of the asterisk denotes the group compared to CL-VNS. All comparisons represent Bonferroni-corrected t-tests to CL-VNS, ***p < 0.0005, **p < 0.005, *p < 0.025. Source data are provided as a Source Data file.