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Measuring and Manipulating Functionally Specific Neural Pathways in the Human Motor System with Transcranial Magnetic Stimulation
Published on: February 23, 2020
Inducing homeostatic-like plasticity in human motor cortex through converging corticocortical inputs
Monika Pötter-Nerger1, Sarah Fischer, Claudia Mastroeni
1Department of Neurology, Christian-Albrechts-University, Kiel, Germany.
Journal of Neurophysiology
|September 4, 2009
Summary
The human primary motor cortex (M1(HAND)) integrates plasticity from different input pathways homeostatically. Prior stimulation affecting corticospinal excitability reversed subsequent plasticity induced by a different method.
Area of Science:
- Neuroscience
- Motor Control
- Neuroplasticity
Background:
- Homeostatic metaplasticity in the human primary motor cortex (M1(HAND)) regulates stimulation-induced changes in corticospinal excitability.
- Previous research utilized transcranial stimulation techniques to investigate these homeostatic mechanisms.
Purpose of the Study:
- To investigate if M1(HAND) integrates long-term depression (LTD)-like and long-term potentiation (LTP)-like plasticity induced by different afferents in a homeostatic manner.
- To examine the interaction between premotor-to-motor and sensory-to-motor plasticity in M1(HAND).
Main Methods:
- Ten healthy volunteers underwent two transcranial stimulation protocols.
- Repetitive transcranial magnetic stimulation (rTMS) of the left dorsal premotor cortex (PMD) induced either LTP-like (5 Hz) or LTD-like (1 Hz) plasticity in left M1(HAND).
- Paired-associative stimulation (PAS) targeting sensory-to-motor inputs to left M1(HAND) was applied subsequently, with interstimulus intervals adjusted to induce LTP-like (PAS(N20+2ms)) or LTD-like (PAS(N20-5ms)) plasticity.
Main Results:
- Premotor-to-motor stimulation induced a homeostatic response to subsequent sensory-to-motor PAS.
- Facilitatory 5 Hz rTMS was followed by suppressed corticospinal excitability with PAS(N20+2ms), and inhibitory 1 Hz rTMS was followed by facilitated excitability with PAS(N20-5ms).
- A negative linear relationship was observed between excitability changes from PMD rTMS and subsequent PAS; no changes in finger-tapping task performance were noted.
Conclusions:
- The human M1(HAND) exhibits a homeostatic response pattern that integrates acute plastic changes from distinct input channels.
- These findings provide evidence for the integration of different plasticity mechanisms within the primary motor cortex.
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