Immediate effect of quadri-pulse stimulation on human brain microstructures and functions

Area of Science:

• Neuroscience
• Neuroimaging
• Brain Stimulation

Background:

• The immediate impact of repetitive brain stimulation on brain microstructure remains largely unknown.
• Understanding these effects is crucial for developing targeted neuromodulation therapies.

Purpose of the Study:

• To investigate immediate microstructural and functional changes in the human brain following repetitive stimulation of the primary motor cortex (M1).
• To determine if excitatory or inhibitory stimulation protocols induce alterations in brain microstructure or functional connectivity.

Main Methods:

• Sixteen healthy adults received excitatory (QPS5) and inhibitory (QPS50) quadri-pulse stimulation (QPS) targeting the left M1.
• Diffusion MRI and resting-state functional MRI were performed before and after QPS to assess microstructural and functional connectivity (FC) changes.

Main Results:

• No significant microstructural alterations were detected in the cerebral cortex after either QPS5 or QPS50.
• Excitatory QPS5 led to a significant decrease in FC between bilateral M1, while QPS50 did not significantly alter FC.
• No correlation was found between microstructural changes and FC alterations.

Conclusions:

• Repetitive stimulation of a single brain area may not be sufficient to induce immediate microstructural changes.
• The observed decrease in functional connectivity after excitatory stimulation suggests potential functional, but not structural, immediate effects.