A guide for concurrent TMS-fMRI to investigate functional brain networks

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Brain Stimulation

Background:

• Transcranial Magnetic Stimulation (TMS) is crucial for causal inference in cognitive neuroscience by directly activating neurons.
• Concurrent TMS-fMRI enables quantification of TMS effects on distant brain activity, but artifacts pose interpretation challenges.

Purpose of the Study:

• To address methodological challenges in concurrent TMS-fMRI and provide a guide for artifact reduction.
• To investigate the impact of TMS intensity on BOLD signal in frontal-striatal circuits.

Main Methods:

• Administered concurrent TMS-fMRI in healthy participants targeting primary motor cortex (M1) and lateral prefrontal cortex (PFC) projections.
• Varied TMS output intensity to assess its effect on brain activity.
• Implemented strategies to minimize artifacts during experimental design and post-processing.

Main Results:

• TMS parametrically increased the Blood-Oxygen-Level-Dependent (BOLD) signal in stimulated regions and their subcortical projections.
• The BOLD signal increase correlated with stimulation intensity.
• Demonstrated successful application of TMS-fMRI for network investigation.

Conclusions:

• Concurrent TMS-fMRI is a viable method for investigating functional brain networks when artifacts are managed.
• This technique allows for precise examination of causal relationships between stimulated areas and connected brain regions.
• The study provides practical guidance for researchers utilizing TMS-fMRI.