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

Stimulation after injury shifts the distribution of CS terminations ventrally in the gray matter. Dorsoventral distributions of mean axon density from the dorsal to the ventral borders of the ipsilateral gray mater are shown. Each line plots the average density of axon terminations (preterminal and terminal axons; no boutons) of the animals in each group; light shading plots ± SEM. Data from controls are shown in black (n = 4 rats); stimulation alone (Stim; n = 4), green; injury alone (n = 5), blue; and combined injury and stimulation (Inj+Stim; n = 5), red. The arrow indicates a ventral location where axon length is greatest in the injury and stimulation group. To normalize for differences in the size of the gray matter across animals, all graphs were interpolated to 1000 points between the dorsal and ventral margins of the gray matter. Calibration: 30 μm of labeled axons.