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Assessing the agreement and consistency of absolute and relative corticospinal stimulus response curves in healthy young adults

Hougland, Juliana R (2023) Assessing the agreement and consistency of absolute and relative corticospinal stimulus response curves in healthy young adults. Master's Thesis, University of Pittsburgh. (Unpublished)

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Stimulus response curves (SRC) use the relationship between transcranial magnetic stimulation (TMS) intensity and motor evoked potential (MEP) amplitude to determine the input-output properties of the corticospinal system. SRCs can be constructed with stimulation intensities based on the absolute stimulator capacity or relative to motor threshold (MT), but the two methods have not been directly compared.
PURPOSE: To determine whether SRC parameters (MEPmax, V50, and slope) produced by absolute and relative SRCs are similar and consistent.
METHODS: Thirty (15W, age: 27.06.3y, height: 171.98.9cm, weight: 80.219.3kg) young, healthy individuals completed absolute (5-100% of stimulator output in 5% increments) and relative (65-160% of active MT (AMT) in 5% increments) SRCs of the rectus abdominis (RA), vastus lateralis (VL), and first dorsal interosseous (FDI) during submaximal voluntary isometric contractions of each target muscle. Two single TMS pulses were delivered at each intensity in a randomized order with the mean MEP fit to a Boltzmann sigmoidal equation to derive MEPmax, V50, and slope. Absolute agreement and consistency of the SRC parameters were determined with intraclass correlation coefficients, Cronbach’s alphas, and Bland-Altman plots. A secondary analysis examined differences in AMT, physical activity, maximal voluntary isometric contraction force, and baseline EMG activity among participants who had one successful SRC (absolute or relative only) using independent samples t-tests.
RESULTS: Absolute and relative SRCs displayed good absolute agreement and consistency for MEPmax and V50 in all muscles, but poor agreement and consistency for slope. Bland-Altman plots showed greater variance for slope with larger mean differences for each muscle compared with MEP¬max and V50. Individuals who successfully fit an absolute SRC in the RA had lower AMTs and higher physical activity levels. No such between-group differences were found for the other measures or muscles.
DISCUSSION: Absolute and relative SRCs produce similar values for the MEPmax and V50 but not slope. Additionally, AMT and physical activity level may influence the success of RA SRCs depending on the SRC technique. Researchers should consider these factors when selecting an SRC method.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Hougland, Juliana Rjrh195@pitt.edujrh195
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairFlanagan, Shawn Dsdf29@pitt.edusdf29
Committee MemberProessl, Felixfsp5@pitt.edufsp5
Committee MemberSterczala, Adam JAJS355@pitt.eduajs355
Committee MemberAllison, Katelyn Fkatelyn.allison@pitt.edukatelyn.allison
Committee MemberLovalekar, Mita Tmital@pitt.edumital
Date: 6 June 2023
Date Type: Publication
Defense Date: 16 March 2023
Approval Date: 6 June 2023
Submission Date: 24 March 2023
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 78
Institution: University of Pittsburgh
Schools and Programs: School of Health and Rehabilitation Sciences > Sports Medicine and Nutrition
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: transcranial magnetic stimulation, corticospinal excitability, stimulus response curve, motor cortex
Date Deposited: 06 Jun 2023 13:53
Last Modified: 06 Jun 2023 13:53

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  • Assessing the agreement and consistency of absolute and relative corticospinal stimulus response curves in healthy young adults. (deposited 06 Jun 2023 13:53) [Currently Displayed]


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