Article Figures & Data
Figures
- Figure 1.
Staggered hemisections paradigm and extent of lesions. A, Schematic representation of the staggered hemisections with the first and second hemisections at right (T5–T6) and left (T10–T11) thoracic levels, respectively, followed by a complete transection at T12–T13. B, Estimation of first and second lesions extent based on histologic analyses for individual cats. The black area represents the lesioned region.
- Figure 2.
Quadrupedal treadmill locomotion before and after staggered hemisections. Electromyography from selected forelimb and hindlimb muscles along with stance phases (thick horizontal lines) of the left (L) and right (R) limbs in Cat AR at 0.4 m/s in (A) the intact state, (B) after the first hemisection, and (C) after the second hemisection. Gray stance phases indicate cycles with 2:1 fore-hind coordination. Note two cycles of the left (LF) or right (RF) forelimb within one right hindlimb (RH) cycle. BB, Biceps brachii; LH, left hindlimb; TRI, Triceps brachii; ECU, extensor carpi ulnaris; SRT, sartorius; SOL, soleus.
- Figure 3.
Coordination between right homolateral limbs before and after staggered hemisection. Polar plots showing phase interval values for right homolateral coupling (phasing between right forelimb (RFL) and right hindlimb contacts) in degrees around the circumference in (A) the intact state, (B) after the first hemisection, and (C) after the second hemisection. After the first and second hemisection, we separated cycles with 1:1 and 2:1 fore-hind coordination where RFL performs two cycles within one right hindlimb cycle. Thus, two phase interval values are found in 2:1 coordination for the first and second forelimb cycles. Right hindlimb cycle durations increase from the center and are plotted in radii. Data are from cat TO.
- Figure 4.
Temporal adjustments during quadrupedal treadmill locomotion before and after staggered hemisections for the group. A, B, Cycle, stance and swing durations for the forelimbs and hindlimbs, respectively. C, Asymmetry indexes of temporal variables (right limb durations minus left limb durations). We averaged 8–36 cycles per cat. The bars represent the mean ± SD for the group (n = 8 cats) while gray circles represent individual data points (mean for each cat). The p values show the main effect of state (one-factor Friedman test). Asterisks indicate significant differences between time points from the Wilcoxon signed-rank test with Bonferroni’s correction.
- Figure 5.
Support periods during quadrupedal treadmill locomotion before and after staggered hemisections for the group. Individual periods of support (nine in total) normalized to right hindlimb cycle duration. The diagrams show the limbs contacting the treadmill surface (in black) while open/white circles indicate limbs in an aerial phase. We averaged 8–36 cycles per cat. The bars represent the mean ± SD for the group (n = 8 cats) while gray circles represent individual data points (mean for each cat). The p values show the main effect of state (one-factor Friedman test). Asterisks indicate significant differences between time points from the Wilcoxon signed-rank test with Bonferroni’s correction.
- Figure 6.
Spatial adjustments during quadrupedal treadmill locomotion before and after staggered hemisections for the group. A, B, Stride length and distances at contact and liftoff for the forelimbs and hindlimbs, respectively. C, Asymmetry indexes of spatial variables (right limb values minus left limb values). We averaged 8–36 cycles per cat. The bars represent the mean ± SD for the group (n = 8 cats) while gray circles represent individual data points (mean for each cat). The p values show the main effect of state (one-factor Friedman test). Asterisks indicate significant differences between time points from the Wilcoxon signed-rank test with Bonferroni’s correction.
- Figure 7.
Homolateral limb interference during quadrupedal treadmill locomotion before and after staggered hemisections for the group. Each panel shows horizontal distances between homolateral limbs at contact and liftoff of (A) the left (LF) and (B) right (RH) forelimb. We averaged 8–36 (17.94 ± 7.08) cycles per cat. The bars represent the mean ± SD for the group (n = 8 cats), while gray circles represent individual data points (mean for each cat). The p values show the main effect of state (one-factor Friedman test). Asterisks indicate significant differences between time points from the Wilcoxon signed-rank test with Bonferroni’s correction. LH, left hindlimb; RH, right hindlimb.
- Figure 8.
Hindlimb-only and quadrupedal treadmill locomotion before and after complete spinal transection. A, Activity from selected hindlimb muscles and stance phases (thick horizontal lines) of the left (LH) and right (RH) hindlimbs in Cat JA at 0.4 m/s. B, Activity from selected hindlimb muscles and stance phases (thick horizontal lines) of the left and right limbs in Cat HO at 0.4 m/s. Gray and blue stance phases indicate cycles with 2:1 (two forelimb cycles within one right hindlimb cycle) and 1:2 (two hindlimb cycles within one right forelimb cycle) fore-hind coordination, respectively. BB, Biceps brachii; LH, left hindlimb; RH, right hindlimb; SOL, soleus; SRT, sartorius; TRI, triceps brachii.
- Figure 9.
Potential changes in spinal sensorimotor circuits after staggered hemisections. In the intact state, descending supraspinal and propriospinal pathways reach lumbar spinal interneurons that control spinal motoneurons. Pathways transmitting signals from proprioceptive and cutaneous afferents ascend to the brain and project locally to spinal interneurons. After the first hemisection performed on the right side, ipsilesional lumbar neurons have weaker activity and increased weight support of the contralesional left hindlimb increases load feedback from extensors and cutaneous afferents. Thicker lines represent increased influence. The left spinal network increases its influence on the right spinal network. New descending and ascending pathways also form to facilitate communication between the brain and spinal cord. After the second hemisection performed on the left side, neurons of the right spinal network have recovered their activity following the first hemisection. Direct ascending and descending pathways are disrupted but new pathways can form through short propriospinal relays. After spinal transection, both the left and right spinal networks function without descending inputs and hindlimb locomotion is expressed, possibly via strengthened sensorimotor interactions bilaterally.
Tables
Cat ID Time point Balance
assistancePerineal stimulation
requiredLeft digitigrade paw
placementRight digitigrade paw
placementTO Hemi 1, wk 2
Hemi 1, wk 8
Hemi 2, wk 3
Hemi 2, wk 7No
No
Yes
YesNo
No
Yes
NoYes
Yes
Yes
YesYes
Yes
Yes
YesJA Hemi 1, wk 2
Hemi 1, wk 8
Hemi 2, wk 2
Hemi 2, wk 7No
No
Yes
YesNo
No
Yes
NoYes
Yes
Yes
YesYes
Yes
Yes
YesAR Hemi 1, wk 2
Hemi 1, wk 8
Hemi 2, wk 1
Hemi 2, wk 7Yes
No
Yes
YesYes
No
Yes
YesYes
Yes
Yes
YesYes
Yes
Yes
YesHO Hemi 1, wk 2
Hemi 1, wk 8
Hemi 2, wk 3
Hemi 2, wk 7No
No
Yes
YesNo
No
No
NoYes
Yes
Yes
YesYes
Yes
Yes
YesMB Hemi 1, wk 2
Hemi 1, wk 7
Hemi 2, wk 3
Hemi 2, wk 8No
No
Yes
YesNo
No
Yes
YesYes
Yes
No
NoYes
Yes
71%
48%GR Hemi 1, wk 1
Hemi 1, wk 8
Hemi 2, wk 3
Hemi 2, wk 8No¸
No
Yes
YesNo
No
No
NoYes
Yes
57%
Yes70%
Yes
Yes
YesKA Hemi 1, wk 2
Hemi 1, wk 8
Hemi 2, wk 3
Hemi 2, wk 7No
No
Yes
YesNo
No
No
NoYes
Yes
Yes
YesYes
Yes
Yes
YesPO Hemi 1, wk 1
Hemi 1, wk 8
Hemi 2, wk 4
Hemi 2, wk 7No
No
Yes
YesNo
No
Yes
YesYes
Yes
26%
YesNo
Yes
Yes
YesLocomotor performance of eight cats using four criteria (balance assistance, requirement of perineal stimulation to evoke locomotion, and proper digitigrade placement of the left and right hindpaw). % values indicate the percentage of cycles with correct digitigrade placement in some cats. The left column is cat identification (ID). In the time point column, Hemi 1 and Hemi 2 refer to the first and second hemisections, respectively. The week that data were collected after the first and second hemisections is indicated for each time point in individual cats. wk = week.
First hemisection Second hemisection Cat ID Weeks 1–2 Weeks 7–8 Weeks 1–4 Weeks 7–8 TO 100% (14/14) 100% (16/16) 62% (8/13) 100% (12/12) JA 58% (7/12) 58% (11/19) 100% (8/8) 96% (22/23) AR 50% (4/8) 100% (21/21) 75% (18/24) 96% (23/24) HO 25% (6/24) 20% (2/10) 71% (12/17) 71% (15/21) MB 100% (22/22) 82% (28/34) 29% (4/14) 11% (2/19) GR 10% (1/10) 19% (7/36) 52% (11/21) 50% (6/12) KA 15% (4/26) 9% (2/23) 100% (21/21) 71% (12/17) PO 33% (6/18) 13% (1/8) 89% (17/19) 88% (7/8) Percent values indicate the percentage of cycles with 2:1 fore-hind coordination, where the left or right forelimb performed two cycles within a right hindlimb cycle. The number in brackets indicates the number of cycles with 2:1 fore-hind coordination dived by the total number of hindlimb cycles recorded for individual cats after the first and second hemisections. The left column is cat identification (ID).
- Table 3
Circular statistics for forelimb-hindlimb coordination before and after staggered hemisections
1:1 coordination 2:1, 1st forelimb cycle 2:1, 2nd forelimb cycle Cat ID Time points r r r TO Intact 0.79* - - Hemi 1, wk 2 - 0.74* 0.68* Hemi 1, wk 8 - 0.75* 0.44* Hemi 2, wk 3 0.91* 0.42 0.60* Hemi 2, wk 7 - 0.70* 0.64* JA Intact 0.86* - - Hemi 1, wk 2 0.45 0.64 0.27 Hemi 1, wk 8 0.74* 0.30 0.35 Hemi 2, wk 2 - 0.83* 0.86* Hemi 2, wk 6 - 0.58* 0.33 AR Intact 0.88* - - Hemi 1, wk 2 0.94* 0.85 0.49 Hemi 1, wk 8 - 0.84* 0.80* Hemi 2, wk 1 0.80* 0.47* 0.54* Hemi 2, wk 7 - 0.51* 0.57* HO Intact 0.97* - - Hemi 1, wk 2 0.57* 0.23 0.48 Hemi 1, wk 8 0.69* - - Hemi 2, wk 3 0.44 0.46 0.48 Hemi 2, wk 7 0.87* 0.42 0.42 MB Intact 0.96* - - Hemi 1, wk 2 - 0.23 0.54* Hemi 1, wk 7 0.52 0.33 0.50* Hemi 2, wk 3 0.71* 0.39 0.49 Hemi 2, wk 8 0.60* 0.48 0.10 GR Intact 1.00* - - Hemi 1, wk 1 0.92* - - Hemi 1, wk 8 0.75* 0.37 0.17 Hemi 2, wk 3 0.38 0.61* 0.12 Hemi 2, wk 8 0.44 0.41 0.39 KA Intact 0.97* - - Hemi 1, wk 2 0.93* 0.12 0.64 Hemi 1, wk 8 0.85* 0.42 0.12 Hemi 2, wk 3 - 0.46* 0.38 Hemi 2, wk 7 0.97* 0.48 0.57* PO Intact 0.90* - - Hemi 1, wk 1 0.88* 0.55 0.70* Hemi 1, wk 8 0.13 - - Hemi 2, wk 4 0.46 0.46* 0.47* Hemi 2, wk 7 - 0.35 0.43 The table shows r values from Rayleigh’s test at the different time points for individual cats before and after hemisections for cycles with 1:1 and 2:1 (first and second forelimb cycles) coordination for right homolateral coupling (the phasing between right forelimb and right hindlimb contacts). The r value measures the dispersion of phase interval values around the mean, with a value of 1 indicating a perfect concentration in one direction and a value of 0 indicating uniform dispersion. We performed Rayleigh’s z test: z = nr2, where n is the sample size (number of cycles) and compared the z value to a critical z value on Rayleigh’s table to determine whether there was a significant concentration around the mean (p < 0.05). Asterisks indicate a significant r value. The left column is cat identification (ID). wk = week.
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