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Time course of disuse-induced corticomotor plasticity in individual human brains: a precision TMS study

Proessl, Felix (2022) Time course of disuse-induced corticomotor plasticity in individual human brains: a precision TMS study. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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The organization of the human brain can be modified by behavior. Disuse reduces skeletomotor and corticomotor function, but the exclusive use of endpoint measures in the disused limb without consideration of spinal or peripheral influences has left the time course, origin and extent of disuse-induced corticomotor adaptations unclear.
PURPOSE: 1) to determine the time course, origin and extent of corticomotor plasticity in response to skeletal muscle disuse, 2) to assess the relationship between disuse-induced changes in corticomotor and skeletomotor function and 3) to examine whether mental imagery (MI) can counteract the disuse-induced skeletomotor and corticomotor loss of function.
METHODS: Six (3W, age: 22.7yrs, BMI: 24.4kg/m2) healthy young adults performed daily assessments of upper- (casted and un-casted first dorsal interosseus) and lower-extremity (non-dominant tibialis anterior) skeletomotor function, corticospinal, spinal and peripheral excitability over the course of twenty-one days. To induce disuse, three participants completed a 7-day immobilization intervention (Cast) after seven days of baseline testing (Pre), which was followed by another seven days of recovery testing (Post). The remaining participants performed a 5-day MI counter-intervention that started 48h after the onset of immobilization. Changes in corticomotor white matter microstructure were assessed with differential tractography between diffusion scans obtained before the first day of testing, three times throughout the intervention and at the end of the study. Changes in skeletomotor and corticomotor function were determined within-subject using ANOVAs (Pre, Cast, Post) with Benjamini-Hochberg corrections for multiple comparisons.
RESULTS: Immobilization markedly reduced casted hand use, strength and fine motor skill. Skeletomotor deficits coincided with reduced white matter microstructure in smaller corticomotor regions and rapid homotopic reductions in corticospinal excitability (CSE) that occurred independent of changes at the spinal or peripheral level and reversed with the recovery of function after cast removal. MI preserved skeletomotor function when CSE was maintained, but had no beneficial effects when CSE decreased.
DISCUSSION: Our results indicate that disuse-induced corticomotor plasticity is homotopic, that the skeletomotor consequences of such adaptations depend on the interplay between supraspinal and peripheral excitability, and that MI may attenuate the loss of skeletomotor function by preserving CSE.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairFlanagan, Shawn
Committee MemberConnaboy,
Committee MemberFerrarelli,
Committee MemberVerstynen,
Date: 7 July 2022
Date Type: Publication
Defense Date: 24 May 2022
Approval Date: 7 July 2022
Submission Date: 27 May 2022
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 150
Institution: University of Pittsburgh
Schools and Programs: School of Health and Rehabilitation Sciences > Rehabilitation Science
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Use-dependent plasticity, TMS, disuse, immobilization
Date Deposited: 07 Jul 2022 18:40
Last Modified: 07 Jul 2022 18:40


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