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Tracking small sensory nerve action potentials in human axonal excitability studies.
James Howells1, Hugh Bostock2, Susanna B Park1
1Brain and Mind Centre, The University of Sydney, Sydney, Australia.
Journal of Neuroscience Methods
|February 15, 2018
Summary
This study introduces a new preamplifier for tracking low-amplitude nerve signals, enabling detailed excitability studies in diseased human sensory axons. The technique allows measurements previously impossible due to small nerve volleys and noise.
Area of Science:
- Neuroscience
- Biomedical Engineering
Background:
- Non-invasive threshold-tracking techniques have advanced in vivo human axon excitability studies.
- Most studies focus on motor axons due to challenges in resolving small sensory nerve volleys amidst noise and stimulus artifacts.
Purpose of the Study:
- To describe novel techniques and a simple, battery-powered preamplifier for tracking low-amplitude compound action potentials.
- To overcome technical limitations in studying diseased sensory axons with pathologically small nerve volleys.
Main Methods:
- Utilized a simple, battery-powered, isolated preamplifier with high common mode rejection (>125 dB) and low noise (<0.4 μV).
- Employed fast non-invasive threshold-tracking with surface stimulation and recording.
- Demonstrated tracking of compound action potentials as small as 2 μV.
Main Results:
- Successfully tracked compound action potentials down to 2 μV without distortion from stimulus artifacts, clamping, filtering, or averaging.
- Enabled measurements from nerves with maximal responses below 15 μV, significantly improving upon previous limitations.
- Presented three recordings from patients with pathologically small nerve action potentials (≤7 μV).
Conclusions:
- The described techniques and preamplifier facilitate the study of diseased axons, particularly sensory nerves with high thresholds and low amplitude potentials.
- This advancement allows for more comprehensive in vivo excitability assessments in neurological disorders affecting sensory pathways.
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