How TMS works

What is TMS?

TMS Therapy involves the use of very short repetitive pulses of magnetic energy to stimulate nerve cells in the brain. First used in 1985, TMS Therapy has been used by researchers around the world to help understand the function of different parts of the brain. Special sequences of repetitive TMS Therapy have been tested by Neuronetics to determine its safety and efficacy for the treatment of major depression. Neuronetics' pivotal trial is not the first to investigate the potential antidepressant effects of TMS Therapy. Early results from other trials have encouraged researchers to further investigate TMS Therapy as a treatment for major depression.

Figure 1 - Limbic Structures          

How TMS Therapy Works

The short pulses of magnetic energy produced by NeuroStar® TMS Therapy System are aimed by the treating clinician at the structures in the brain thought to control mood. (See Figure 1, Limbic System Structures, many of which are thought to be involved in mood regulation). The left prefrontal cortex (Figure 2) is used to access these structures non-invasively from outside the brain with TMS Therapy. The unique nature of magnetic fields allows them to pass through the skull and into the cortex without being distorted in any way. This facilitates a very focal type of stimulation, minimizing stimulation of brain tissue not involved in mood. 
 
 

Figure 2 - Treatment Site               

   
Once inside the brain, the dynamic (rapidly changing) nature of the magnetic pulses induces electrical charges to flow. The amount of electricity created in the brain is very small, and can not be felt by the patient. When in the correct orientation relative to brain cells (neurons), these very small electric charges can cause the neurons to fire or become active. (Figure 3) The objective of TMS Therapy is to stimulate (or activate) brain cells. Patients remain awake and alert during a TMS Therapy procedure.
 

Figure 3 - Neuron Diagram              

Brain Scans of depressed vs. non-depressed patients

Notice the hypoactivity of the brain regions in the depressed patient on the left