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In Vivo Intracellular Recording of Type-Identified Rat Spinal Motoneurons During Trans-Spinal Direct Current Stimulation
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Does trans-spinal and local DC polarization affect presynaptic inhibition and post-activation depression?
D Kaczmarek1,2,3, J Ristikankare1, E Jankowska1
1Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden.
The Journal of Physiology
|November 29, 2016
Summary
Direct current (DC) polarization affects spinal reflexes differently depending on application. Local DC application shows polarity-dependent effects, while trans-spinal DC stimulation (tsDCS) facilitates spinal modulatory systems.
Area of Science:
- Neuroscience
- Spinal Cord Physiology
- Electrophysiology
Background:
- Direct current (DC) polarization is explored for neurological deficits.
- Trans-spinal DC stimulation (tsDCS) mechanisms are less understood than transcranial DC stimulation.
- Spinal modulatory systems like presynaptic inhibition and post-activation depression are key to reflex control.
Purpose of the Study:
- Investigate DC effects on spinal presynaptic inhibition and post-activation depression.
- Compare local intraspinal DC (locDC) and trans-spinal DC stimulation (tsDCS) effects.
- Determine if DC can modulate exaggerated or weakened spinal reflexes.
Main Methods:
- Used anesthetized rats for spinal cord studies.
- Applied local intraspinal DC (0.3-0.4 μA) and trans-spinal DC stimulation (0.8-1.0 mA).
- Examined polarity-dependent effects of locDC and tsDCS on spinal reflexes.
Main Results:
- Local DC application demonstrated polarity-dependent effects: cathodal enhanced, anodal weakened presynaptic inhibition and post-activation depression.
- Trans-spinal DC stimulation (tsDCS) facilitated both systems regardless of polarity.
- Both DC application methods suggest common DC-sensitive mechanisms for these spinal modulatory systems.
Conclusions:
- Local DC may counteract both overactive and underactive spinal reflexes.
- tsDCS might worsen pathologically weakened spinal activity.
- Findings contribute to understanding basic properties of spinal presynaptic inhibition and post-activation depression.
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