How spinalized rats can walk: biomechanics, cortex and hindlimb muscle scaling – implications for rehabilitation

Ann N Y Acad Sci, 2010 · DOI: 10.1111/j.1749-6632.2010.05534.x · Published: June 1, 2010

Simple Explanation

Neonatal spinalized rats can achieve autonomous weight supported locomotion never seen after adult injury. This suggests that the younger animals' nervous systems are more adaptable. One factor that helps these rats walk is that the muscles in their legs develop in proportion to normal rats, regardless of how well the rats can walk. This allows the spinal cord to effectively control the limbs. The trunk, which connects the front and back of the rat, also plays a key role. The part of the brain that controls the trunk becomes more important in rats that can walk after spinal injury.

Study Duration

Not specified

Participants

9 normal rats, 11 NWSNST rats and 10 WSNST rats

Evidence Level

Not specified

Key Findings

1
Neonatal spinalized rats can develop autonomous weight-supported stepping, unlike adult spinalized rats.
2
Trunk motor representations in the cortex are essential for hindlimb weight-supported locomotion in adult rats spinalized as neonates.
3
The whole leg musculature scales proportionally to normal rat musculature in NST rats, regardless of function.

Research Summary

Neonatal spinalized rats can achieve autonomous weight-supported locomotion, unlike adult spinalized rats, suggesting greater plasticity in the developing nervous system. Trunk control, influenced by cortical trunk motor representations, plays a crucial role in the locomotion of these rats, helping to coordinate forelimb-hindlimb mechanics. Preserved muscle scaling, where leg musculature develops proportionally to normal rats regardless of function, is essential for effective use of pattern generation mechanisms in the spinal cord.

Practical Implications

Rehabilitation Strategies

Rehabilitation efforts should focus on maximizing trunk integration and enabling injured rats to explore novel control strategies.

Therapeutic Interventions

Therapies aimed at training trunk control are likely to be beneficial in assisting locomotion recovery.

Understanding Plasticity

Further research is needed to determine if the same reorganization of control and movement strategies seen in NST rats are possible in adult spinalized rats.

Study Limitations

1
It is not yet clear if the same reorganization of control and movement strategies as are seen in NST rats are possible in adult spinalized rats.
2
NST rats likely learn their motor strategies in critical periods in development. Whether injured adults can re-learn these is an open question.
3
The muscle soleus and plantaris were not examined which were difficult to dissect accurately in the perfused NST rats.

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