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Corticospinal Excitability Modulation During Action Observation
Published on: December 31, 2013
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Inter-Individual Variability in Motor Output Is Driven by Recruitment Gain in the Corticospinal Tract Rather Than
Arkaprovo Sarkar1,2, Alish Dipani2, Giorgio Leodori3,4
1Human Motor Neurophysiology and Neuromodulation Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India.
Brain Sciences
|October 27, 2022
Summary
Individual responses to brain stimulation vary, hindering clinical use. This study identifies key input-output curve parameters, like peak slope and maximum amplitude, that predict motor-evoked potential amplitude and its variability, paving the way for more consistent outcomes.
Area of Science:
- Neuroscience
- Neurophysiology
- Biomedical Engineering
Background:
- Individual variability in response to non-invasive brain stimulation (NIBS) limits clinical applications.
- Motor-evoked potential (MEP) amplitude predicts response to transcranial magnetic stimulation (TMS), but its predictors and variability are unclear.
Purpose of the Study:
- To identify input-output curve (IOC) parameters that best predict MEP amplitude.
- To determine which IOC parameters predict MEP amplitude variability.
Main Methods:
- Analysis of IOC data from 75 subjects.
- General linear modeling (GLM) using IOC parameters to predict MEP amplitude at 120% resting motor threshold (RMT).
- Bootstrapping IOC parameter variability and incorporating it into GLM to identify predictors of MEP amplitude variability.
Main Results:
- Peak slope, motor threshold, and maximum MEP amplitude were significant predictors of MEP amplitude at 120% RMT.
- Variability in MEP amplitude was primarily driven by the variability of peak slope and maximum MEP amplitude.
- Recruitment gain and maximum corticospinal excitability are key predictors of MEP amplitude and its variability.
Conclusions:
- Peak slope and maximum MEP amplitude are crucial determinants of MEP amplitude and its inter-individual variability.
- Achieving a uniform IOC slope could potentially reduce variability in motor output.
- Understanding these predictors may help optimize NIBS protocols for more predictable clinical outcomes.
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