Improving the efficacy and reliability of rTMS language mapping by increasing the stimulation frequency

Area of Science:

• Neuroscience
• Cognitive Science

Background:

• Repetitive transcranial magnetic stimulation (rTMS) at 5-10 Hz is standard for language mapping.
• Current methods face limitations in error generation, reliability, and subject comfort.

Purpose of the Study:

• To investigate the impact of varying rTMS frequencies (10, 30, 50 Hz) on language mapping.
• To enhance the number, reliability, and cortical distribution of evoked language errors.
• To assess tolerability and discomfort associated with different rTMS frequencies.

Main Methods:

• 15 healthy subjects underwent rTMS at 10, 30, and 50 Hz during a picture naming task.
• Stimulation was applied to the left hemisphere across two sessions.
• Error rates, reliability (ICC), and subjective pain ratings were analyzed.

Main Results:

• 30 Hz rTMS yielded significantly more errors than 50 Hz; error rates were similar between 30/50 Hz and 10 Hz.
• Error rates were higher in the first session compared to the second.
• 50 Hz rTMS demonstrated moderate reliability (ICC=.597), outperforming 10 Hz (ICC=.315) and 30 Hz (ICC=.427).
• Higher frequencies (30, 50 Hz) were perceived as less painful than 10 Hz.

Conclusions:

• Higher rTMS frequencies (30-50 Hz) enhance language mapping by increasing error reliability and reducing discomfort.
• These findings support the use of higher frequencies for more effective and tolerable language mapping.
• Frequency selection should consider the specific region of interest for optimal outcomes.