Figure 2.

Cruise quality quantifications during SC regeneration. (A,B) Cruise periods at a water current velocity of 10 cm/s. Snapshots of swim behavior prior to injury are shown in (A) and at 1 wpi in (B). Overlayed swim forms shown below the separate frames highlight defective caudal movement after SC transection. (C) Experimental schematic to develop quantifiable gait quality measurements. A diagram showing keypoint and angle positions labeled on a fish’s centerline. A DeepLabCut model was trained to identify the keypoints, then the curvature between three adjacent keypoints were calculated at each angle position. The rostral region of the fish corresponds to angle positions α₁ to α₅. (D) Cruise curvature profiles (control, 1 wpi, and 8 wpi) for male fish that regenerated less than 20% of the glial tissue at the lesion site. Each cruise curvature profile represents the mean lateral angular amplitude along the dorsal centerline while cruising. The vertical dotted line separates rostral and caudal positions, demonstrating that acutely injured fish swim with markedly elevated curvature in the rostral portion of their body. (E) Cruise curvature profiles (control, 1 wpi, and 8 wpi) for male fish that regenerated more than 20% of the glial tissue at the lesion site. (F) Quantification of rostral compensation in male fish that regenerated less than 20% of the glial tissue at the lesion site. Rostral compensation represents the displacement between cruise profiles. This score is the maximum distance, on the vertical axis, between rostral positions of a cruise profile from the control profile. Angle positions α₁ to α₅ from Panel D were used to define the rostral region. (G) Rostral compensation scores for male fish that regenerated more than 20% of the glial tissue at the lesion site. (H) Tail beat frequency for male fish in still water (0 cm/s), measured at each assayed week. ANOVA was not significant for tail beat frequencies. (I) Strouhal numbers for male fish in still water (0 cm/s), measured at each assayed week. Strouhal number is a unitless value related to vortex shedding mechanics and is defined as tail beat frequency times peak-to-peak amplitude of the tail tip divided by speed of forward motion. ANOVA was not significant for Strouhal numbers. Panels D and F include 11, 5, 4, 5, 6, 7, 9, 9, 8 fish at control, 1, 2, 3, 4, 5, 6, 7, and 8 wpi assays, respectively. Panels E and G include 16, 9, 9, 13, 11, 14, 12, 12, 13 fish at control, 1, 2, 3, 4, 5, 6, 7, and 8 wpi assays, respectively. Panels H and I include 30, 16, 14, 18, 17, 22, 21, 21, 21 fish at control, 1, 2, 3, 4, 5, 6, 7, and 8 wpi assays, respectively. Error bars depict SEM and statistical significance was determined by Brown-Forsythe and Welch’s ANOVA tests with Dunnett’s T3 multiple comparisons tests. p-value markers in black represent comparisons between each time point post-injury relative to control measurements prior to injury. Red horizontal bars and p-values marked in red show significance between 1 wpi and 8 wpi. ***p < 0.001; **p < 0.01; *p < 0.05; ns, p > 0.05.