Activity dependent stimulation increases synaptic efﬁcacy in spared pathways in an anesthetized rat model of spinal cord contusion injury

Restorative Neurology and Neuroscience, 2022 · DOI: 10.3233/RNN-211214 · Published: January 1, 2022

Simple Explanation

This study investigates a potential therapy called activity-dependent stimulation (ADS) for spinal cord injury (SCI). ADS involves using electrical stimulation of the spinal cord triggered by signals from the brain. The goal is to strengthen the remaining connections between the brain and spinal cord after an injury, potentially improving motor control. Researchers tested different timings and patterns of stimulation to see how they affected the strength of these connections in rats with SCI. The study found that ADS could increase the activity of spinal cord neurons, suggesting that it can help to strengthen the connections between the brain and spinal cord after SCI. This provides support for ADS as a potential therapy to enhance motor control after SCI.

Study Duration

4 Weeks

Participants

24 adult male Sprague Dawley rats

Evidence Level

Level II; Animal study

Key Findings

1
ADS increased cortically-evoked spikes in spinal cord neurons at specific combinations of spike-ISMS delays and numbers of pulses.
2
Efficacy in descending motor pathways was increased throughout all dorsoventral depths of the hindlimb spinal cord.
3
Different populations of spinal cord neurons are differentially strengthened by different time delays.

Research Summary

This study investigated the effects of activity-dependent stimulation (ADS) on synaptic efficacy in spared motor pathways after spinal cord injury (SCI) in rats. The researchers found that ADS, using intraspinal microstimulation (ISMS) triggered by cortical spikes, could increase cortically-evoked spikes in spinal cord neurons, indicating enhanced synaptic efficacy. The study also showed that the effectiveness of ADS varied depending on the spike-ISMS delay and the number of ISMS pulses, with different combinations affecting different areas of the spinal cord.

Practical Implications

Potential Therapeutic Approach

ADS may serve as a therapeutic approach for enhancing motor control following SCI by strengthening spared pathways.

Optimizing Stimulation Parameters

The study highlights the importance of optimizing stimulation parameters, such as spike-ISMS delays and pulse numbers, to maximize the effectiveness of ADS.

Future Research Directions

Future research should focus on chronic administration of ADS and direct measurement of behavioral outcomes to validate the clinical relevance of these findings.

Study Limitations

1
The necessity to remove and reinsert the microelectrodes between ADS sessions and test bouts.
2
Potential for neuronal damage with each reinsertion of the electrode.
3
The extracellular spike recordings were derived from a heterogeneous group of spinal cord neurons that were not speciﬁcally characterized.

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