fNIRS TMS Studies

Advantages and Considerations for fNIRS-TMS studies

Combining fNIRS with TMS has several advantages, including: the absence of electromagnetic interference between the TMS pulse and the optical signal, better temporal resolution than fMRI or PET, and both a small and portable imaging unit. However, several technical considerations are important:       

• The overall height profile of the optodes needs to be minimized to prevent magnetic field loss due to increased distance between the coil and the scalp. NIRx provides optodes specially designed for TMS, with an overall height profile less than 10mm.

• To streamline data analysis, TMS pulses must be synchronized with fNIRS data acquisition. All NIRx devices have either 4- or 8-bit digital trigger inputs which can be connected to the trigger output ports of TMS devices.

• The mechanical contact between the TMS coil and the optodes can perturb the optical contact between the optode tip and the skin, possibly causing artifacts. NIRx provides a complete TMS solution, including optode stabilizers and retaining caps, that make the complete setup much more robust.

• TMS stimulation might produce hemodynamic changes not only through neurovascular coupling but through other vascular mechanisms that need to be accounted for when analyzing fNIRS traces. The NIRx Support Team provides comprehensive scientific support throughout your research projects starting from experiment planning to data analysis.