Considering how important it is, the dorsolateral prefrontal is surprisingly small. And because everybody's brain is a little different, its precise location can vary slightly from one person to the next. But in TMS, precise location of the stimulus is essential along with intensity, frequency, and duration. By altering these parameters in different ways, TMS can be used for different purposes. For example, fast, excitatory TMS applied to the left dorsolateral prefrontal cortex has been approved by the FDA as a
TMS was developed at the same time functional brain imaging was being perfected. Functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) have allowed us to map cortical function with unprecedented detail and accuracy. For example, in the right cerebral cortex, we have separate circuits that allow us to tell the difference between pitch, rhythm, and harmony whenever we hear music. And in the left cortex, we have separate circuits which allow us to recognize a word if we
For over 40 years now, there's been a lot of talk about neurotransmitters, which has given rise to the popular notion that depression is caused by some sort of chemical imbalance in the brain. According to this popular "neuro-mythology", depression is caused by a deficiency of one or more neurotransmitters and treating depression is simply a matter of restoring these neurotransmitter levels to normal. There is some truth to this, but it's a lot more complicated. Neurotransmitters play just one role
The fact that TMS is a very effective acute treatment for depression has long been established, but one lingering question has remained: how long do the effects last? In a study to determine the durability of the effects of TMS, a consortium of psychiatric researchers has found it to be an effective, long-term treatment for depression. Results of the study, led by Philip G Janicak, MD, a professor at Chicago's Rush University Medical Center, were published in the October
In order to understand how TMS works, it's important to know a little bit about the biophysics underlying the technology. The earth is surrounded by a magnetic field which shields us from harmful cosmic rays. The magnetic field strength of TMS is 30,000 times greater than the earth's magnetic field and is about the same strength as a standard MRI machine. But you could lie in one these all day and you wouldn't be very happy. Magnetic resonance imaging uses a
