Characterizing changes in the excitability of corticospinal projections to proximal muscles of the upper limb

Carson, Richard G., Nelson, Barry D., Buick, Alison R., Carroll, Timothy J., Kennedy, Niamh C. and Mac Cann, Rachel (2013) Characterizing changes in the excitability of corticospinal projections to proximal muscles of the upper limb. Brain Stimulation, 6 5: 760-768. doi:10.1016/j.brs.2013.01.016


Author Carson, Richard G.
Nelson, Barry D.
Buick, Alison R.
Carroll, Timothy J.
Kennedy, Niamh C.
Mac Cann, Rachel
Title Characterizing changes in the excitability of corticospinal projections to proximal muscles of the upper limb
Journal name Brain Stimulation   Check publisher's open access policy
ISSN 1935-861X
1876-4754
Publication date 2013-09-01
Year available 2013
Sub-type Article (original research)
DOI 10.1016/j.brs.2013.01.016
Open Access Status Not yet assessed
Volume 6
Issue 5
Start page 760
End page 768
Total pages 9
Place of publication Philadelphia, PA, United States
Publisher Elsevier
Language eng
Abstract Background: There has been an explosion of interest in methods of exogenous brain stimulation that induce changes in the excitability of human cerebral cortex. The expectation is that these methods may promote recovery of function following brain injury. To assess their effects on motor output, it is typical to assess the state of corticospinal projections from primary motor cortex to muscles of the hand, via electromyographic responses to transcranial magnetic stimulation. If a range of stimulation intensities is employed, the recruitment curves (RCs) obtained can, at least for intrinsic hand muscles, be fitted by a sigmoid function.
Formatted abstract
Background: There has been an explosion of interest in methods of exogenous brain stimulation that induce changes in the excitability of human cerebral cortex. The expectation is that these methods may promote recovery of function following brain injury. To assess their effects on motor output, it is typical to assess the state of corticospinal projections from primary motor cortex to muscles of the hand, via electromyographic responses to transcranial magnetic stimulation. If a range of stimulation intensities is employed, the recruitment curves (RCs) obtained can, at least for intrinsic hand muscles, be fitted by a sigmoid function.

Objective/hypothesis: To establish whether sigmoid fits provide a reliable basis upon which to characterize the input-output properties of the corticospinal pathway for muscles proximal to the hand, and to assess as an alternative the area under the (recruitment) curve (AURC).

Methods: A comparison of the reliability of these measures, using RCs obtained for muscles that are frequently the targets of rehabilitation. Results: The AURC is an extremely reliable measure of the state of corticospinal projections to hand and forearm muscles, which has both face and concurrent validity. Construct validity is demonstrated by detection of widely distributed (across muscles) changes in corticospinal excitability induced by paired associative stimulation (PAS).

Conclusion(s): The parameters derived from sigmoid fits are unlikely to provide an adequate means to assess the effectiveness of therapeutic regimes. The AURC can be employed to characterize corticospinal projections to a range of muscles, and gauge the efficacy of longitudinal interventions in clinical rehabilitation.
Keyword Motor evoked potentials
Goodness of fit
Plasticity
Arm
Afferent stimulation
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Human Movement and Nutrition Sciences Publications
 
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