PT stimulation reduces the electrical threshold of previously silenced CST axons for evoking contralateral motor responses. Lines plot the computed regression lines of changes in current threshold for 8 cats receiving stimulation after prior inactivation between weeks 8 and 11. Ordinate plots change in threshold current. Current reduction is indicated by negative slope. Solid lines are from animals in which there the correlation coefficients were significant (i.e., p ≤0.05). Dotted lines plot data from two animals in which the correlation coefficients were not significant.