Effect of diabetes on motor representations in the M1 and CST in rats. The area of facial motor areas is not affected by diabetes in M1 of STZ rats, but the areas of forelimb and hindlimb are reduced in STZ rats. In particular, the hindlimb area was severely reduced from the earliest stage of the disease. Length-dependent CST damage may account for this. In 23-week STZ rats, stimulation of CST fibers at the C3 or L1 level, the antidromic field potential of CST neurons can be recorded from the responsive hindlimb area. In contrast, the antidromic field potential of the CST neuron in the non-responsive hindlimb area were recorded when stimulated with C3, but not with L1. This suggests that the CST fibers in the atrophied hindlimb region retain potential excitation up to C3 but lose it at the L1 level. * p < 0.05 vs control, *** p < 0.001. Arrow indicate stimulus artifact. The figures are modified with permission [29].