Figure 5.

The effect of heterogeneity and anisotropy on model predictions of neural excitation. (a) Distributions of the stimulation threshold voltages (V_th) of DCF axons located ≤ 3 mm from the electrode surface. Outliers (red plus signs) are > 1.5 times the interquartile range from the ends of the boxes. The different anisotropic, heterogeneous cases are summarized in section 2.3. CPR = cross-property relationship (Tuch et al., 2001). Note: analyses in this work were conducted on the entire population of DCF axons. We show only a subset of the DCF axons in panel a because it demonstrates that axons greater than 3 mm from the electrode are unlikely to be activated at the stimulation amplitudes used in clinical practice (1–10 V). (b) The potentials in the brain with increasing × displacement from the surface of contact 0.