Healthy Young Participants
Conditions
Keywords
Non-invasive brain stimulation
Brief summary
In this study we applied TMS to the hand area of M1 whilst acquiring fMRI of the brain. This study tested whether a higher-frequency form of brain stimulation, called high-gamma (100Hz) intermittent theta burst stimulation (iTBS), more effectively increases brain excitability than the standard 50Hz iTBS. In a double-blind, randomized study with 22 healthy participants, brain activity and motor responses were measured using TMS-fMRI. The 100Hz iTBS condition produced stronger and more consistent increases in motor excitability and greater activation of sensorimotor brain regions compared to 50Hz and sham stimulation, suggesting it may be a more effective approach for non-invasive neuromodulation.
Detailed description
This study investigates whether a modified form of brain stimulation called high-gamma intermittent theta burst stimulation (iTBS) can more effectively and consistently increase brain excitability compared to the standard iTBS protocol. iTBS is a non-invasive method that uses magnetic pulses to influence brain activity, but responses vary widely between people. In this double-blind, randomized, within-subject study, 22 healthy adults completed three sessions of brain stimulation combined with functional MRI (TMS-fMRI). Each participant received conventional 50Hz iTBS, high-gamma 100Hz iTBS, and a sham (placebo) condition on separate visits. Changes in motor cortex excitability were measured using motor-evoked potentials (MEPs), and brain activity and connectivity were assessed using fMRI. The results showed that 100Hz iTBS produced stronger and more reliable increases in cortical excitability compared to both the 50Hz and sham conditions. High-gamma iTBS also activated broader areas of the sensorimotor network and showed stronger links between stimulation strength and neural response. These findings suggest that high-gamma iTBS may be a more effective and physiologically relevant approach for non-invasive brain stimulation in humans.
Interventions
DEVICEIntermittent theta burst stimulation (iTBS) as a protocol of repetitive transcranial magnetic stimulation (rTMS)
iTBS applies a train of 3 pulses of stimulation, delivered at a gamma frequency, then repeated 10x at a theta repetition rate. Intensity of stimulation is personalized based on the individual's resting motor threshold, determined at the start of the session and delivered at 70% of this.
Sponsors
Ecole Polytechnique Fédérale de Lausanne
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Right handed
Exclusion criteria
* Contraindications to either TMS or MRI: Pregnant Metal implants Use of recreational drugs Neurological conditions History of seizures or epilepsy
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Functional magnetic resonance imaging (fMRI) | Throughout the whole experiment, for a total of 26mins | fMRI of the brain and spinal chord were acquired during stimulation with single pulse TMS to elucidate the changes in BOLD activity occurring from the intervention. |
| Motor evoked potentials (MEPs) | MEPs are measured for 8mins immediately before intervention, then 15mins after intervention for a further 8mins. | When single pulses of TMS are applied to M1 hand region, MEPs are evoked in the corresponding hand muscle which can be measured with electromyography (EMG). The amplitude of the MEPs before and after the iTBS interventions are then measured and compared to determine the response to the iTBS, whether this is facilitation, suppression, or no change. |
Countries
Switzerland
Outcome results
None listed