The Effects of Priming Intermittent Theta Burst Stimulation on Movement-Related and Mirror Visual Feedback-Induced Sensorimotor Desynchronization

Abstract

Background: The potential benefits of priming intermittent theta burst stimulation (iTBS) with continuous theta burst stimulation (cTBS) have not been examined in regard to sensorimotor oscillatory activities recorded in electroencephalography (EEG). Objective: The objective of this study was to investigate the modulatory effect of priming iTBS (cTBS followed by iTBS) delivered to the motor cortex on movement-related and mirror visual feedback (MVF)-induced sensorimotor event-related desynchronization (ERD), compared with iTBS alone, on healthy adults.Methods: Twenty participants were randomly allocated into Group 1: priming iTBS - cTBS followed by iTBS, and Group 2: non-priming iTBS - sham cTBS followed by iTBS. The stimulation was delivered to the right motor cortex daily for 4 consecutive days. EEG was measured before and after 4 sessions of stimulation. Movement-related ERD was evaluated during left-index finger tapping and MVF-induced sensorimotor ERD was evaluated by comparing the difference between right-index finger tapping with and without MVF.Results: After stimulation, both protocols increased movement-related ERD and MVF-induced sensorimotor ERD in high mu and low beta bands, indicated by significant time effects. A significant interaction effect favoring Group 1 in enhancing movement-related ERD was observed in the high mu band (F (1, 18) = 4.47, p = 0.049), compared with Group 2.Conclusion: Our experiment suggests that priming iTBS with cTBS delivered to the motor cortex yields similar effects with iTBS alone on enhancing sensorimotor activation induced by movement and MVF-based observation on healthy adults. Further studies are warranted.

Priming Intermittent Theta Burst Stimulation for Hemiparetic Upper Limb After Stroke: A Randomized Controlled Trial

“…This finding differed from a study with healthy adults, in which 4-session priming iTBS increased the movement-related ERD. 24 Our study found that ERD triggered by different tasks might represent different sensorimotor processing, and movement-related ERD might be expressed in different manners in stroke patients, compared with their healthy counterparts. Neuroimaging studies have demonstrated that patients with chronic stroke showed an overactivation of bilateral motor-related areas during paretic hand movements, relative to their healthy counterparts.…”

“…Participant in Group 3 received cTBS at 20% RMT followed by iTBS at 20% RMT (ie, sham stimulation). Sham stimulation was delivered using the same coil with 20% RMT, 24 which significantly eliminated the TMS-induced electrical fields in the cortex (Figure 1C, the simulation of electrical field was performed using SimNIBS 25 ). We measured the RMT of the contralesional M1 to determine the intensity of stimulation.…”

“…Signals were processed using EEGLab. 30 A widely used paradigm for MVF-based movement observation was used 24,31 that included the following 2 conditions: (1) nonparetic index-finger tapping with MVF, with participants being asked to perform finger taps 3 times on a keyboard button with the index-finger of their unaffected side, in response to an auditory cue (ie, a 300-ms beep sound), delivered at random intervals (of from 7 to 10 seconds), and to relax their hand after the completion of the movement. Participants were requested to look at the mirrored reflection of their unaffected index-finger in a physical mirror (406×432 mm) that was placed over their midsagittal plane between both arms.…”

Dose-response relationship between iTBS and prefrontal activation during executive functioning: A fNIRS study

“…First, we did not have a real sham condition in this experiment. Nonetheless, our study included a low intensity (50% RMT) condition, comparable to a number of TMS studies that have adopted the strategy of lowering stimulation intensity as a sham condition (49,71,72). Second, due to the inherent limitation of the fNIRS equipment used, such as the height profile of our fNIRS probes we were unable to measure the hemodynamic response to iTBS during and immediately after the stimulation.…”