TMS Mapping
Explained

If you are considering transcranial magnetic stimulation (TMS) therapy, you have probably heard the term “brain mapping” or “motor threshold mapping.” Don’t let these technical terms intimidate you – the procedure is easily tolerated. Mapping is a straightforward and crucial first step in your TMS journey. Think of it as creating a personalized roadmap for your treatment, much like a GPS, which needs your exact location to guide you to your destination.
In this post, we’ll explain TMS mapping, why it’s essential for treatment success, and what you can expect during the process. Whether researching TMS or preparing for your first session, this guide will help you understand this critical step on your path to wellness.

TMS Mapping
Explained

If you are considering transcranial magnetic stimulation (TMS) therapy, you have probably heard the term “brain mapping” or “motor threshold mapping.” Don’t let these technical terms intimidate you – the procedure is easily tolerated. Mapping is a straightforward and crucial first step in your TMS journey. Think of it as creating a personalized roadmap for your treatment, much like a GPS, which needs your exact location to guide you to your destination.
In this post, we’ll explain TMS mapping, why it’s essential for treatment success, and what you can expect during the process. Whether researching TMS or preparing for your first session, this guide will help you understand this critical step on your path to wellness.

What Is Transcranial Magnetic Stimulation?

TMS is a non-invasive procedure that uses magnetic pulses to stimulate specific brain areas, similar to an MRI but more targeted. It’s FDA-approved for treating conditions like depression, particularly when medications have not provided adequate relief. TMS does not require anesthesia or recovery time. During treatment sessions, a magnetic coil is placed against the head, delivering carefully calibrated pulses that help regulate neural activity involved in mood regulation and other functions.
What Is Transcranial Magnetic Stimulation

Why Do We Need Brain Mapping?

Like no two fingerprints are the same, every person’s brain is uniquely different in structure and organization. This is why TMS mapping is essential – it helps us find the precise spot where the treatment will work best for each individual.
Think of it this way: if you’re trying to deliver a package, you need the exact address, not just the neighborhood. TMS mapping shows the place in the brain where the magnetic pulses will be most effective. Such preparation is essential to deliver treatment to the optimal location and achieve the best results.
During mapping, your TMS provider identifies the “motor threshold” – the minimum amount of magnetic stimulation needed to create a response in the brain. This is crucial because:
By mapping the brain, we prepare for the best possible outcome. This small investment of time makes a big difference in the patient’s TMS journey.

What Happens During a Mapping Session?

Before we begin, you will be seated in a comfortable treatment chair similar to the one used by a dentist. Your TMS provider will explain each step, and you will be fully awake and alert throughout the process. They will also ask you to remove any jewelry or items with magnetic-sensitive metals within 12 inches of the coil.
First, the TMS provider will use a soft m tape to analyze the shape of your head. This will help them make reference points and find the same spot for each future treatment. Think of it as creating a map with coordinates, which will be used throughout your TMS therapy.
This is where the actual mapping begins. The provider will place the TMS coil over a specific area of your brain and deliver single magnetic pulses. The goal is to find the spot that makes your thumb twitch slightly. Don’t worry – this sensation isn’t painful, just unusual. It might feel like a light tapping on your head. The TMS provider will adjust the intensity based on your motor cortex excitability until they find the right level that causes the slight thumb movement.
After finding your motor threshold, the practitioner will use this as a reference point to locate the treatment area. They will move the coil to different positions, making minor adjustments until they find the optimal spot for stimulation. This procedure is painless and easily tolerated. The TMS provider will constantly check in with you to ensure your comfort.
Finally, all measurements and settings will be carefully documented. This will ensure that every TMS procedure will deliver the right intensity to precisely the same spot. The provider might also take photos or use markers to help replicate the exact position in future sessions.

The mapping process with a motor threshold identification usually takes 30-60 minutes. This method is common in clinics with NeuroStar® and BrainsWay® TMS devices. However, some providers use equipment with neuronavigation, which streamlines data acquisition and helps avoid coil positioning errors.

What Is Neuronavigation?

Neuronavigation is the most advanced approach to brain mapping in TMS therapy. It uses imaging technology (usually an MRI scan) to create a detailed 3D model of the patient’s brain, allowing the provider to see exactly where they are targeting the stimulation. With the reliable maps created, acquiring data is no longer necessary because the process is automated.
During the first treatment session, small sensors are placed on the patient’s head, working together with a special camera system that tracks their position in real time. This technology provides precise coordinates, matching the TMS coil’s external position with the brain’s internal structures. The provider can see exactly where the magnetic pulses are being delivered, taking the guesswork out of the targeting process.
The real advantage of neuronavigation is its accuracy and reliability. Once the TMS provider identifies the optimal treatment location, they can return to the same spot every time, even if you move your head during treatment. This consistency is crucial for achieving the best possible outcomes.
While the traditional mapping method is still effective, neuronavigation adds an extra layer of precision that can be particularly effective for certain patients or specific treatment goals. Many TMS providers with MagVenture®, Magstim®, and Nextstim® devices use this valuable tool regularly in their practice. It allows them to acquire TMS maps in digital format and automatically adjust coil placement.
What Is Neuronavigation

What to Expect From Brain Mapping?

Most patients tolerate the mapping procedure well. You will be seated comfortably throughout the session and communicate with your TMS provider anytime. While patients must keep their heads relatively still, the chair is designed for comfort. Wear comfortable clothing, and feel free to bring a bottle of water.
During mapping, you will experience tapping sensations on your scalp – these are the magnetic pulse at work. You might feel:
These sensations are normal and temporary. While they might feel unusual, they are not painful. If you experience discomfort, let your provider know immediately so they can adjust the settings of the TMS device.
Your safety is always the top priority during cortical mapping. Before beginning:
Throughout your mapping session, you will be accompanied by trained professionals who will:

After Mapping, What's Next?

The mapping data collected becomes the foundation for the entire TMS therapy course. The precise measurements, motor threshold, and optimal stimulation location are carefully documented in the patient’s treatment protocol. This information creates a personalized “prescription” that includes the exact position of the coil, stimulation intensity, and other technical parameters needed for effective therapy.
Once preparation is complete, regular TMS sessions can begin – often on the same day as the mapping session. Each treatment follows the documented protocol, ensuring the magnetic pulses are delivered to the correct location with the right intensity.
Throughout the treatment course, the TMS team monitors response and comfort levels. Sometimes, minor adjustments might be needed, including:
If significant changes in response occur, a brief re-mapping session might be recommended to ensure optimal treatment. The goal is to maintain the highest level of effectiveness, reliving depression symptoms and other mental health conditions while providing comfort and safety throughout TMS therapy.

Key Takeaways

Brain mapping is a fundamental first step that sets the foundation for successful TMS treatment. It involves finding the motor threshold and using innovative technology like neuronavigation. While the procedure might seem technical, it is straightforward, well-tolerated, and completed in a single session. The time invested in precise mapping pays off through better treatment outcomes and enhanced comfort.
Key Takeaways