Researchers found differences in how brain regions work together during certain cognitive tasks, which may help clinicians more effectively treat and assess obsessive-compulsive disorder.

A team in the lab of Theresa Desrochers, PhD, the Rosenberg Family Associate Professor of Brain Science and an associate professor of psychiatry and human behavior at Brown, examined potential links between abstract sequencing and OCD for the study, which was published in Imaging Neuroscience.

“We started looking into OCD because symptoms of the condition suggest that patients lose track or get stuck where they are while performing sequences,” says lead study author Hannah Doyle PhD’25, a postdoctoral research associate in Desrochers’ lab.

For the study, participants performed a sequential cognitive task while in an MRI, naming the color or shape of an object in a specific order. Doyle found that while people with OCD were able to perform the sequence as well as the control group (people who were not diagnosed with OCD), the MRI scans revealed differences in brain regions connected to motor and cognitive task control, working memory, and object recognition.

“Their behavior looked similar, but the brains of the participants with OCD recruited more brain regions than the people in the control group,” Doyle says. Some of the regions hadn’t previously been linked to OCD, she adds.

Co-author Nicole McLaughlin, PhD, an associate professor of psychiatry and human behavior, says the findings may lead to new treatment targets for OCD, especially when involving transcranial magnetic stimulation. TMS, which uses magnetic pulses to stimulate brain regions implicated in a psychiatric disorder, leads to improvement in about 30 to 40 percent of OCD patients; McLaughlin says it might be even more effective if the newly implicated regions are targeted.

The real-life relevance of the cognitive task used in the study was key to the team’s insights, Desrochers says.

“A lot of tasks that are used in a clinical setting are static,” she says. “But as humans, we interact with the world through sequences, where we organize information and make decisions. So we’re asking people to do a task where these different control systems have to interact.”

The sequencing task calls for participants to name the colors or shapes of a series of images in a particular order—such as color, color, shape, shape—requiring the ability to keep track of a sequence while making a categorization decision.

“This task gets us closer to understanding what actually looks different in the brain for folks with OCD when all of these different cognitive control systems are trying to work together,” Desrochers says.

The researchers are testing the possibility of using the sequence task itself as an assessment tool.

“We are planning to use the task between treatments,” McLaughlin says. “If we start to see OCD patients’ brains looking more like control participants when they perform the task, that could help indicate that TMS treatment may be effective for symptom reduction.”