Non-invasive Mapping of Face Processing by Navigated Transcranial Magnetic Stimulation

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neurosurgery

Background:

• Frontal and parietal lobe tumor resections can lead to neuropsychological deficits, including prosopagnosia.
• Non-navigated transcranial magnetic stimulation (TMS) is established for mapping cortical functions.
• The need exists for precise mapping of face processing areas for potential preoperative planning.

Purpose of the Study:

• To assess the feasibility and spatial resolution of repetitive navigated TMS (rTMS) for mapping face processing.
• To detect face processing impairment in healthy volunteers using rTMS.
• To establish rTMS mapping for preoperative assessment in brain tumor patients.

Main Methods:

• Twenty healthy, right-handed volunteers underwent bilateral rTMS mapping of cortical face processing.
• A 5 Hz/10 pulse stimulation protocol was used across 52 predetermined cortical sites.
• Participants named portraits during rTMS application, with errors recorded.

Main Results:

• rTMS induced naming errors in the right middle frontal gyrus (mMFG) in 80% of subjects.
• Anomia errors were most frequent (35%) in the bilateral triangular inferior frontal gyrus (trIFG).
• Bilateral frontal lobe errors occurred in 10% of subjects for similar or incorrect name recognition.

Conclusions:

• rTMS is a feasible method for mapping cortical face processing functions.
• rTMS can induce detectable face processing impairments, with localizations aligning with existing literature.
• The mapping technique did not interfere with language functions, suggesting potential clinical utility for preoperative planning.