How Insights From Epilepsy Patients Could Lead to New Treatments for PTSD

Take a quick look at the word below. What color is the text?

If it took you a moment to separate the meaning of the word (green) from the color of the text itself (red), don’t feel bad. The conflict is intentional, designed to test your brain’s cognitive flexibility when faced with two competing pieces of information.

Processing and resolving conflicting information is something that most of us do on a daily or even hourly basis, typically without much conscious thought.

However, for individuals suffering from post-traumatic stress disorder (PTSD), the brain circuit responsible for this conflict resolution can go haywire.

There is a growing body of research suggesting that the symptoms of PTSD—sudden bouts of extreme fear or anxiety that are not tied to specific threats—may be caused in part by the brain’s inability to process and resolve two conflicting signals:

  • I am in danger
  • I am safe

The difficulty in resolving these two conflicting messages may help to explain the high rate of PTSD in combat veterans. A high level of alertness and threat awareness can be beneficial when deployed in a war zone, but can be counterproductive when trying to resume everyday life after returning home.

A team of researchers at Massachusetts General Hospital is investigating whether deep brain stimulation could help to restore the proper functioning of this conflict resolution system in individuals with treatment-resistant PTSD.

The work, which is led by investigators from the Division of Neurotherapeutics in the Department of Psychiatry, is supported by a federal grant from the Defense Advanced Research Projects Agency (DARPA).

About Deep Brain Stimulation

Deep brain stimulation (DBS) is a treatment strategy that uses electrodes that are surgically implanted in relevant regions of the brain to deliver an electrical current designed to resolve faulty signaling.

DBS has been successfully used to treat several complex neurological and psychological disorders, including Parkinson’s disease, dystonia, treatment-resistant depression and obsessive compulsive disorder. Due to the invasive nature of the treatment (implantation typically involves two separate surgeries), it is typically used only in cases where other treatment strategies have failed.

The Epilepsy Connection

Ishita Basu, PhD
Ishita Basu, PhD

Ishita Basu, PhD, a postdoctoral research fellow in the Division of Neurotherapeutics, has been working with a unique study population—epilepsy patients who have been implanted with electrodes for seizure monitoring—to identify the areas of the brain responsible for conflict resolution.

The patients who take part in the research study agree to perform a series of computer tasks that are designed to test their capability to resolve conflicts. This is meant to test how cognitively flexible they are in changing their strategies to solve conflicting situations. Researchers can use the implanted electrodes to monitor the patients’ brain activity as they complete different tasks, and to see if the patients’ performance can be improved by applying electrical stimulation.

“We are looking at how fast they react to or resolve the conflict, and we have seen that stimulating certain regions of the brain in a precise manner makes them faster,” Basu explains. “We think this will translate to a patient whose anxiety is preventing him or her from resolving a conflicting situation. Maybe if we stimulate the brain at the right place and the right time, he or she can get out of that situation.”

For example, if an individual with PTSD starts to experience stress while riding in a crowded but otherwise safe train car, stimulating the area of the brain that helps to resolve these two conflicting messages (I am in danger versus I am safe) could give the brain the boost it needs to correctly assess and resolve the situation: The train car is crowded, which makes me uncomfortable, but I am otherwise safe.

A Welcome Challenge

Basu finds the challenges of brain signal processing more interesting than traditional electrical engineering projects, and likes working as part of a multidisciplinary team.

“This is a field where people from all disciplines can contribute a lot. We need people from medicine, engineering, math and psychology to bring in their ideas,” she says.

“It also has a feel-good factor. I may not be helping people directly right now, but someday the work could help.”

DARPA Approved for Public Release, Distribution Unlimited

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