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Vagus Nerve Stimulation as a Tool to Induce Plasticity in Pathways Relevant for Extinction Learning
Published on: August 21, 2015
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High intensity VNS disrupts VNS-mediated plasticity in motor cortex
Robert A Morrison1, Tanya T Danaphongse2, Stephanie T Abe2
1The University of Texas at Dallas, School of Behavioral Brain Sciences, Richardson, TX, United States; The University of Texas at Dallas, Texas Biomedical Device Center, Richardson, TX, United States.
Brain Research
|February 4, 2021
Summary
Vagus nerve stimulation (VNS) intensity matters for brain plasticity. Moderate VNS enhances motor cortex function, but high intensity VNS disrupts this effect, impacting recovery after neurological injury.
Area of Science:
- Neuroscience
- Neuroplasticity
- Rehabilitation Science
Background:
- Vagus nerve stimulation (VNS) paired with motor rehabilitation aids functional recovery after neurological injury.
- VNS-induced plasticity in motor networks is key, with an inverted-U relationship observed between VNS intensity and cortical plasticity.
Purpose of the Study:
- To investigate the interaction between moderate and high intensity VNS trains to understand mechanisms of VNS-dependent plasticity.
- To determine how VNS parameter changes affect plasticity magnitude and VNS-enhanced recovery efficacy.
Main Methods:
- Rats underwent a behavioral task involving VNS paired with jaw movement during chewing for five days.
- Three VNS conditions were tested: Standard VNS (moderate intensity), Interleaved VNS (alternating moderate and high intensity), and Short VNS (reduced moderate intensity).
- Intracortical microstimulation (ICMS) assessed motor cortex representations post-stimulation.
Main Results:
- 100 pairings of moderate intensity VNS significantly enhanced motor cortex plasticity.
- Replacing moderate with high intensity VNS blocked this plasticity enhancement.
- Reducing VNS pairings to 50 moderate intensity pairings reinstated plasticity.
Conclusions:
- High intensity VNS creates a refractory period of at least 8 seconds, preventing moderate intensity VNS from engaging synaptic reorganization mechanisms.
- Stimulation parameter adjustments are critical determinants of plasticity magnitude and the effectiveness of VNS in promoting recovery.
