Sensory Circuit Remodeling and Movement Recovery After Spinal Cord Injury

Frontiers in Neuroscience, 2021 · DOI: 10.3389/fnins.2021.787690 · Published: December 8, 2021

Simple Explanation

Restoring sensory circuit function after spinal cord injury (SCI) is essential for recovery of movement, yet current interventions predominantly target motor pathways. Integrated cortical sensorimotor networks, disrupted by SCI, are critical for perceiving, shaping, and executing movement. Following SCI, in the motor cortex, corticocortical circuits undergo dynamic remodeling; however, it remains unknown how rehabilitation shapes the plasticity of S1-M1 networks or how these changes may impact recovery of movement.

Study Duration

Not specified

Participants

Non-human primates and rodents

Evidence Level

Review

Key Findings

1
Proprioceptive feedback is indispensable for both driving functional recovery as well as for maintaining that recovered function after SCI.
2
SCI disrupts afferent input to the central nervous system and results in the reorganization of cortical sensory representations, or maps.
3
Rehabilitation may be used to effectively shape S1 remodeling as fMRI imaging in non-human primates trained on a reach-to-grasp task shows reactivation of somatosensory cortex after unilateral dorsal column lesion S1.

Research Summary

This review explores the role of sensory circuit remodeling in movement recovery after spinal cord injury (SCI), emphasizing the importance of sensorimotor integration and cortical plasticity. The review highlights that proprioceptive feedback and reactivation of S1 responses to cutaneous stimulation play a critical role in recovery of locomotor function and tactile sensitivity after SCI. The review concludes by advocating for further studies using modern in vivo imaging tools and sensitive behavioral tasks to understand active circuit changes following SCI, which could aid in designing therapeutic strategies for movement recovery.

Practical Implications

Rehabilitation Strategies

Targeted sensorimotor training can improve recovery of locomotor function and tactile sensitivity after SCI.

Therapeutic Development

Understanding the circuit mechanisms of rehabilitation-dependent S1 cortical plasticity can provide critical data for designing therapeutic strategies for the recovery of movement after SCI.

Future Research

The use of modern in vivo imaging tools and sensitive sensory and motor behavioral tasks will facilitate a deeper understanding of active circuit changes following SCI.

Study Limitations

1
The circuit mechanisms underlying functional reorganization of sensory and motor cortex after SCI are not well-characterized.
2
Studies have lacked the cellular resolution to measure the circuits involved.
3
Most mapping studies have been limited by the use of anesthesia, and are not measures of active sensation in awake, behaving animals.

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