Associative plasticity in the human motor cortex is enhanced by concurrently targeting separate muscle representations with excitatory and inhibitory protocols

Kamke, Marc R., Nydam, Abbey S., Sale, Martin V. and Mattingley, Jason B. (2016) Associative plasticity in the human motor cortex is enhanced by concurrently targeting separate muscle representations with excitatory and inhibitory protocols. Journal of Neurophysiology, 115 4: 2191-2198. doi:10.1152/jn.00794.2015


Author Kamke, Marc R.
Nydam, Abbey S.
Sale, Martin V.
Mattingley, Jason B.
Title Associative plasticity in the human motor cortex is enhanced by concurrently targeting separate muscle representations with excitatory and inhibitory protocols
Journal name Journal of Neurophysiology   Check publisher's open access policy
ISSN 0022-3077
1522-1598
Publication date 2016-04-01
Year available 2016
Sub-type Article (original research)
DOI 10.1152/jn.00794.2015
Open Access Status Not Open Access
Volume 115
Issue 4
Start page 2191
End page 2198
Total pages 8
Place of publication Bethesda, MD, United States
Publisher American Physiological Society
Language eng
Subject 2800 Neuroscience
1314 Physiology
Abstract Paired associative stimulation (PAS) induces changes in the excitability of human sensorimotor cortex that outlast the procedure. PAS typically involves repeatedly pairing stimulation of a peripheral nerve that innervates an intrinsic hand muscle with transcranial magnetic stimulation over the representation of that muscle in the primary motor cortex. Depending on the timing of the stimuli (interstimulus interval of 25 or 10 ms), PAS leads to either an increase (PAS 25) or a decrease (PAS 10) in excitability. Both protocols, however, have been associated with an increase in excitability of nearby muscle representations not specifically targeted by PAS. Based on these spillover effects, we hypothesized that an additive, excitability-enhancing effect of PAS 25 applied to one muscle representation may be produced by simultaneously applying PAS 25 or PAS 10 to a nearby representation. In different experiments prototypical PAS 25 targeting the left thumb representation [abductor pollicis brevis (APB)] was combined with either PAS 25 or PAS 10 applied to the left little finger representation [abductor digiti minimi (ADM)] or, in a control experiment, with PAS 10 also targeting the APB. In an additional control experiment PAS 10 targeted both representations. The plasticity effects were quantified by measuring the amplitude of motor evoked potentials (MEPs) recorded before and after PAS. As expected, prototypical PAS 25 was associated with an increase in MEP amplitude in the APB muscle. This effect was enhanced when PAS also targeted the ADM representation but only when a different interstimulus timing (PAS 10) was used. These results suggest that PAS-induced plasticity is modified by concurrently targeting separate motor cortical representations with excitatory and inhibitory protocols.
Formatted abstract
Paired associative stimulation (PAS) induces changes in the excitability of human sensorimotor cortex that outlast the procedure. PAS typically involves repeatedly pairing stimulation of a peripheral nerve that innervates an intrinsic hand muscle with transcranial magnetic stimulation over the representation of that muscle in the primary motor cortex. Depending on the timing of the stimuli (interstimulus interval of 25 or 10 ms), PAS leads to either an increase (PAS25) or a decrease (PAS10) in excitability. Both protocols, however, have been associated with an increase in excitability of nearby muscle representations not specifically targeted by PAS. Based on these spillover effects, we hypothesized that an additive, excitability-enhancing effect of PAS25 applied to one muscle representation may be produced by simultaneously applying PAS25 or PAS10 to a nearby representation. In different experiments prototypical PAS25 targeting the left thumb representation [abductor pollicis brevis (APB)] was combined with either PAS25 or PAS10 applied to the left little finger representation [abductor digiti minimi (ADM)] or, in a control experiment, with PAS10 also targeting the APB. In an additional control experiment PAS10 targeted both representations. The plasticity effects were quantified by measuring the amplitude of motor evoked potentials (MEPs) recorded before and after PAS. As expected, prototypical PAS25 was associated with an increase in MEP amplitude in the APB muscle. This effect was enhanced when PAS also targeted the ADM representation but only when a different interstimulus timing (PAS10) was used. These results suggest that PAS-induced plasticity is modified by concurrently targeting separate motor cortical representations with excitatory and inhibitory protocols.
Keyword Paired associative stimulation
Transcranial magnetic stimulation
Plasticity
Motor cortex
Motor evoked potential
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID APP1028210
CE140100007
FL110100103
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
Queensland Brain Institute Publications
School of Psychology Publications
 
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