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Modulation of dorsal premotor cortex disrupts neuroplasticity of primary motor cortex in young and older adults
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  • Wei-Yeh Liao,
  • George Opie,
  • Ulf Ziemann,
  • John Semmler
Wei-Yeh Liao
The University of Adelaide

Corresponding Author:wei-yeh.liao@adelaide.edu.au

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George Opie
The University of Adelaide
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Ulf Ziemann
Eberhard Karls University Tübingen Faculty of Medicine
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John Semmler
The University of Adelaide
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Abstract

Previous transcranial magnetic stimulation (TMS) research suggests that dorsal premotor cortex (PMd) influences neuroplasticity within primary motor cortex (M1) through indirect (I) wave interneuronal circuits. However, it is unclear how the influence of PMd on the plasticity of M1 I-waves changes with advancing age. This study therefore investigated the neuroplastic effects of intermittent theta burst stimulation (iTBS) to M1 early and late I-wave circuits when preceded by iTBS (PMd iTBS-M1 iTBS) or sham stimulation (PMd sham-M1 iTBS) to PMd in 15 young and 16 older adults. M1 excitability was assessed with motor evoked potentials (MEP) recorded from right first dorsal interosseous using posterior-anterior (PA) and anterior-posterior (AP) current TMS at standard stimulation intensities (PA1mV, AP1mV) and reduced stimulation intensities (PA0.5mV, early I-waves; AP0.5mV, late I-waves). PMd iTBS-M1 iTBS disrupted the expected facilitation of PA0.5mV (to M1 iTBS) in young and older adults (P = 0.009), whereas the intervention had no effect on AP0.5mV facilitation in either group (P = 0.305). This suggests that the influence of PMd on M1 plasticity is preserved in older adults and may involve projections to early I-wave circuits within M1.
19 Feb 2024Submitted to European Journal of Neuroscience
19 Feb 2024Review(s) Completed, Editorial Evaluation Pending
19 Feb 2024Reviewer(s) Assigned
15 Apr 20241st Revision Received
16 Apr 2024Submission Checks Completed
16 Apr 2024Assigned to Editor
29 Apr 2024Review(s) Completed, Editorial Evaluation Pending