Electrical Stimulation of Spared Corticospinal Axons Augments Connections with Ipsilateral Spinal Motor Circuits after Injury

Stimulation and injury each promote increased density of ipsilateral CS terminations, which is further augmented in the combined condition. A, Axon density (terminals and preterminal axons) maps. B, Bouton density maps. Color coded average density maps are shown for controls (A1, B1; n = 4), animals with PT stimulation alone (Stim; A2, B2; n = 4), animals with injury (PTx) alone (A3, B3; n = 5), and animals with both stimulation and injury (Inj+Stim; A4, B4; n = 5). The ipsilateral gray matter border (gray hatched line) shows averaged borders from the individual animals in the group. Calibration: 500 μm; Color scale: A, 0–5.7 μm axon/μm² area; B, 0–0.7 boutons/μm² area.