Fig. 1.

Preclinical electrode scaling. A: examples of a 1 × 8 clinical cylindrical percutaneous lead and a 4 × 8 clinical paddle lead provided by Boston Scientific. The contact dimensions are 3 mm × 1.35 mm and 3.18 mm × 1.4 mm, respectively. The appropriate size of spinal cord stimulation (SCS) electrodes for subsequent computational modeling and preclinical experimentation was determined by scaling the dimensions of these contacts with respect to the cross-sectional area of the mouse spinal cord. B: comparison of relative sizes of human, rat, and mouse T10 spinal cord. C: example mouse cross section generated from an anatomic atlas of the spinal cord. Cyan and orange lines depict gray and white matter boundaries, respectively. D: rat and mouse error comparisons for major and minor axes: magnitude of the differences in the lengths of the major and minor axes between an unscaled rat T10 spinal cord and scaled mouse T10 spinal cord, plotted as a function of the mediolateral (major) and dorsoventral (minor) scaling factors applied to the mouse spinal cord. Colors denote magnitudes of the total difference in lengths of the major and minor axes measured in mm. This analysis supports a rat-to-mouse scaling factor of 1.8 (white box). When related to the previously determined human-to-rat scaling factor, the human-to-mouse scaling factor is 4.5.