Characterization of recovered walking patterns and motor control after contusive spinal cord injury in rats

Brain and Behavior, 2012 · DOI: 10.1002/brb3.71 · Published: September 1, 2012

Spinal Cord Injury Neurology Rehabilitation

Simple Explanation

This study investigates how rats recover their ability to walk after a spinal cord injury that mimics the kind humans experience. Researchers looked at the movements of their hind legs and the activity of specific muscles during walking on a treadmill. The study found that even though the rats improved their walking, they still had problems with certain parts of the step, especially the 'yield' phase where the leg absorbs the impact of landing. A specific muscle, the semitendinosus, didn't work quite right during this phase. By changing the treadmill to a slight downhill slope, the researchers were able to improve the activity of the semitendinosus muscle. This suggests that focusing on specific types of exercises could help people with spinal cord injuries improve their walking ability.

Study Duration

3 weeks

Participants

14 female Sprague-Dawley rats

Evidence Level

Not specified

Key Findings

1
Deficits in the yield (E2) phase of locomotion and a caudal shift of locomotor subphases persisted throughout the 3-week recovery period after contusive SCI in rats.
2
EMG records showed notable deficits in the semitendinosus (ST) during yield, with changes in recruitment patterns during recovery; the dual-burst pattern was lost at 7 days and returned by 21 days, but latencies remained impaired.
3
ST2 burst duration is highly predictive of open field Basso, Beattie, Bresnahan (BBB) scores, indicating a correlation between specific muscle activity and overall locomotor recovery.

Research Summary

This study characterized locomotor recovery in rats after contusive SCI, focusing on hindlimb kinematics and EMG recordings during treadmill walking. The researchers found persistent deficits in the yield phase (E2) and a caudal shift in locomotor subphases throughout the 3-week recovery period. EMG analysis revealed notable deficits in the semitendinosus (ST) muscle during the yield phase, with altered recruitment patterns during recovery. The typical dual-burst pattern of ST was initially lost but returned by 21 days, although latencies remained impaired. The study demonstrated that ST2 burst duration is highly predictive of open field BBB scores and that simple changes in locomotor specificity, such as downhill treadmill walking, can enhance eccentric actions and result in new motor patterns after SCI.

Practical Implications

Targeted Rehabilitation Strategies

The findings suggest that targeted rehabilitation strategies focusing on enhancing eccentric motor control and addressing specific muscle impairments, such as those in the semitendinosus, may improve locomotor recovery after SCI.

Task-Specific Training

The restoration of ST2 activity during downslope treadmill walking highlights the potential of task-specific training to restore specific motor patterns and improve locomotor function.

Biomarker for Recovery

The correlation between ST2 burst duration and BBB scores suggests that ST2 activity may serve as a biomarker for assessing locomotor recovery and evaluating the effectiveness of rehabilitation interventions.

Study Limitations

1
The study could not measure relative amplitude of EMG patterns due to chronic electrode implantation.
2
The study focused on a specific type of SCI (contusive) and a specific animal model (rats), limiting the generalizability of the findings.
3
The study only examined a limited number of muscles (TA, LG, ST), potentially overlooking other important factors contributing to locomotor recovery.

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