Brain mapping is an important part of transcranial magnetic stimulation (TMS) treatment. In this article, Mindpath Health’s National TMS Medical Director Christina Ni, MD discusses the process of determining a patient’s correct treatment area and dosage.

TMS Patient being consulted by TMS technician

What is brain mapping?

The first transcranial magnetic stimulation (TMS) appointment is typically the longest during the treatment series. Before the first treatment session, a TMS psychiatrist will conduct a brain mapping procedure to determine the optimal treatment location and the power or “dose” appropriate for each patient.

Brain mapping, also known as cortical mapping, is the process of pinpointing the left dorsolateral prefrontal cortex (DLPFC), a spot in the brain above the left temple, which is known to be critical in the expression of depression symptoms. This is where the TMS treatment is applied.

Understanding the dorsolateral prefrontal cortex (DLPFC)

The DLPFC processes a variety of cognitive functions. In addition to working on short-term memory, this area governs a person’s emotional response to people, places, and events. This part of the brain is also active when making risky and difficult decisions.

For people with depression, the DLPFC tends to be underactive, the level of which directly correlates to the severity of their symptoms. This area is intricately linked to many areas of the brain, including the limbic system, which is deep in the brain and tasked with behavioral and emotional responses. Depression can affect the whole brain, and the DLPFC works with other areas of the brain to improve depression symptoms.

How the brain mapping process works

To identify the DLPFC treatment area, a TMS psychiatrist must first locate the primary motor cortex. Also known as the motor pathway, this area of the brain lies across the top of your head from ear to ear. Different areas along this strip control movement in various parts of the body.

Clinicians will use the TMS device to deliver short magnetic pulses to the area of the motor pathway that controls movement of the right hand. When the TMS psychiatrist has located the correct spot, known as the motor hot spot, the right hand’s thumb or other fingers will show consistent movement.

The TMS psychiatrist will use the motor hot spot as a landmark to map the optimal treatment location to target the DLPFC. Then, the TMS psychiatrist will position the magnetic coil, part of the TMS device, over the motor hot spot to begin the TMS treatment.

During the TMS treatment series, a TMS psychiatrist will perform a second or third brain mapping to reassess the ideal location and power and to maintain the accuracy of the treatment location.

Learn more about TMS and other mental health topics

Want to learn more about your mental health? Visit our Patient Resources for articles, tips, and education from Mindpath Health’s clinicians. Visit our TMS page to learn more about how TMS can help with treatment-resistant depression

Christina Ni, MD

Calabasas, CA

Dr. Christina Ni is a board-certified psychiatrist. She promotes a multifaceted approach toward achieving optimal health through improving mental and physical health, including diet, exercise, and self-care. Dr. Ni is a strong advocate for transcranial magnetic stimulation (TMS) as a modality for treatment-resistant psychiatric illnesses and has seen the beneficial transformation of TMS treatment in people’s lives. Dr. Ni graduated from the University ... Read Full Bio »

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