What Is The Optimal Frequency Range And Amplitude Of Transcranial Magnetic Stimulation (TMS) To Induce A Therapeutic Effect On Gamma-band Oscillations In The Prefrontal Cortex Of Individuals With Treatment-resistant Depression, While Minimizing The Risk Of Inducing Seizures In Susceptible Populations?

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To address the use of transcranial magnetic stimulation (TMS) for treatment-resistant depression while minimizing seizure risk, the optimal approach involves the following considerations:

  1. Frequency Range:

    • Target the gamma-band oscillations (30-100 Hz) to potentially enhance neural synchronization and cognitive processing.
    • Consider using theta burst stimulation (TBS), which applies bursts of three pulses at 50 Hz, mimicking natural plasticity patterns and possibly aligning with gamma frequencies.

  2. Amplitude:

    • Use the minimum effective intensity, typically just above the individual's motor threshold, to balance efficacy and safety.
    • Lower amplitudes reduce the risk of seizures, especially in susceptible populations.

  3. Stimulation Pattern:

    • Employ patterned protocols like TBS (either intermittent or continuous) for efficacy, as these may be more effective than continuous rTMS in modulating oscillations.

  4. Targeting:

    • Utilize navigated TMS with MRI guidance for precise targeting of the prefrontal cortex, potentially allowing lower intensities due to accuracy.

  5. Session Parameters:

    • Optimize the number of sessions and pulses to achieve a therapeutic effect without overstimulation, balancing efficacy and safety.

By integrating these elements, the approach aims to enhance gamma-band oscillations therapeutically while minimizing seizure risk, particularly through precise targeting, lower amplitudes, and effective stimulation patterns.