Boosting and Mapping Non-invasive Brain Stimulation Techniques

Overview

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.

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.