Abstract
Objective: To investigate effects of neuroanatomy on changes in corticomotor excitability after intermittent theta burst stimulation (iTBS). Simulated transcranial magnetic stimulation of MRI-derived head models was paired with empirically collected motor evoked potentials (MEPs) in the upper limb due to its relevance to activities of daily living and related rehabilitation efforts.
Methods: Ten individuals participated, completing two separate sham-controlled iTBS sessions (one each targeting the biceps and first dorsal interosseus (FDI) cortical hotspots) and an MRI. MEPs were acquired with a Magstim BiStim2 stimulator while iTBS was delivered via a Super Rapid2 Plus1 stimulator, both with 70 mm figure-of-eight coils. Stimulation targeted the primary motor cortex and electromyography was collected from dominant biceps and FDI. Resting motor threshold (RMT) served as a measure of empirical stimulation responsiveness. Head models were generated from T1 & T2 weighted MRI. Diffusion tensor imaging was used to extract fiber tract geometry for the biceps and FDI corticospinal tracts. Neuroanatomical parameters established were fiber tract surface area (FTSA), tract fiber count (TFC), and brain scalp distance (BSD). Cortical electric field strength (EFS) was determined by simulated magnetic stimulation of head models and finite element analysis. A linear mixed effects model was used to find effects of these parameters on MEPs.
Results: For the FDI, there was no effect of iTBS (p = 0.223) but individual changes in corticomotor excitability due to stimulation type scaled with RMT (p < 0.001), EFS (p = 0.001), BSD (p = 0.004), and FTSA (p = 0.011). iTBS was faciliatory on the biceps (p = 0.013) which was dependent on FTSA (p < 0.001) and TFC (p < 0.001).
Conclusion: MRI-based measures of target-specific neuroanatomy impact how the motor system responds to iTBS. MRI-based modeling of individual neuroanatomy may be useful in selection of motor targets in designing iTBS therapies
Methods: Ten individuals participated, completing two separate sham-controlled iTBS sessions (one each targeting the biceps and first dorsal interosseus (FDI) cortical hotspots) and an MRI. MEPs were acquired with a Magstim BiStim2 stimulator while iTBS was delivered via a Super Rapid2 Plus1 stimulator, both with 70 mm figure-of-eight coils. Stimulation targeted the primary motor cortex and electromyography was collected from dominant biceps and FDI. Resting motor threshold (RMT) served as a measure of empirical stimulation responsiveness. Head models were generated from T1 & T2 weighted MRI. Diffusion tensor imaging was used to extract fiber tract geometry for the biceps and FDI corticospinal tracts. Neuroanatomical parameters established were fiber tract surface area (FTSA), tract fiber count (TFC), and brain scalp distance (BSD). Cortical electric field strength (EFS) was determined by simulated magnetic stimulation of head models and finite element analysis. A linear mixed effects model was used to find effects of these parameters on MEPs.
Results: For the FDI, there was no effect of iTBS (p = 0.223) but individual changes in corticomotor excitability due to stimulation type scaled with RMT (p < 0.001), EFS (p = 0.001), BSD (p = 0.004), and FTSA (p = 0.011). iTBS was faciliatory on the biceps (p = 0.013) which was dependent on FTSA (p < 0.001) and TFC (p < 0.001).
Conclusion: MRI-based measures of target-specific neuroanatomy impact how the motor system responds to iTBS. MRI-based modeling of individual neuroanatomy may be useful in selection of motor targets in designing iTBS therapies
Original language | English |
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Pages | 1601 (P1.042) |
Number of pages | 1 |
DOIs | |
Publication status | Published - 7 Dec 2021 |
Event | 4th International Brain Stimulation Conference - Charleston, United States Duration: 7 Dec 2021 → 10 Dec 2021 Conference number: 4th https://neuromodec.org/events/4th-international-brain-stimulation-conference-2/ |
Conference
Conference | 4th International Brain Stimulation Conference |
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Country/Territory | United States |
City | Charleston |
Period | 7/12/21 → 10/12/21 |
Internet address |
Keywords
- Corticospinal Tract
- Simulation
- Fiber Tracts
- Neuroplasticity