Mouse performance on the horizontal ladder test 1 day after stroke correlates with stroke size at 6 weeks after stroke. (a) Single frame shot from a video of a mouse traversing the horizontal ladder. The arrow identifies a left front paw error. (b and c) Percent error with the left front paw as measured on the ladder test correlates significantly with the percent right hemisphere remaining at 6 weeks after stroke in two separate mouse cohorts. P and R ² values are from linear regression with the Stroke group mice; lines on graphs correspond to Stroke (circles) and Sham (triangles) groups. Large Stroke, red; All Stroke, red + orange. (d) Percent right hemibrain remaining in each group after stratification. Student's t-test ***P < 0.0001; *P < 0.05. Bars, SEM.