Fig 2. Eigenvalue and anisotropy distributions for the entire spinal cord. A, Primary eigenvalue (₁) histogram for control group. Bin frequency is shown as gray-scale level across the entire spinal cord (bin size = 1 x 10^–5 mm²/s). Superimposed on the gray-scale histogram is the group mean and SD (solid black line and error bars). B, Secondary eigenvalue (₂) histogram for control group. Bin frequency is shown as a gray-scale level across the entire spinal cord (bin size = 1 x 10^–5 mm²/s). Superimposed on the gray-scale histogram is the group mean and SD (solid black line and error bars). C, Tertiary eigenvalue (₃) histogram for the control group. Bin frequency is shown as a gray-scale level across the spinal cord (bin size = 1 x 10^–5 mm²/s). Superimposed on the gray-scale histogram is the group mean and SD (solid black line and error bars). D, Fractional anisotropy histogram for control group. Bin frequency is shown as a gray-scale level across the spinal cord (bin size = 0.01). Superimposed on the gray-scale histogram is the group mean and SD (solid black line and error bars).