Researchers at Brown University have identified distinct patterns of brain activity in individuals with obsessive-compulsive disorder (OCD) while they perform cognitively demanding sequential tasks, despite no differences in behavioural performance compared with people without the condition.
The study, published in Imaging Neuroscience on 6th January 2026, was led by researchers in the laboratory of Theresa Desrochers, an associate professor of brain science and of psychiatry and human behaviour at Brown University’s Carney Institute for Brain Science. Desrochers studies abstract-sequential behaviour, which refers to actions that follow a general order even when specific steps vary, such as getting dressed in the morning.
Obsessive-compulsive disorder (OCD) is a prevalent psychiatric condition marked by repetitive thoughts and compulsive actions that cause significant distress. The researchers examined whether disruptions in abstract sequencing are linked to OCD symptoms.
“We started looking into OCD because symptoms of the condition suggest that patients lose track or get stuck where they are while performing sequences,” said lead study author Hannah Doyle, a postdoctoral research associate in Desrochers’ lab.
Participants with OCD and a control group completed a sequential cognitive task inside a magnetic resonance imaging (MRI) scanner. They were asked to name the colour or shape of objects in a prescribed order, such as “colour, colour, shape, shape,” requiring them to track the sequence while making categorisation decisions.
Although individuals with OCD performed the task as accurately as those in the control group, functional MRI (fMRI) scans revealed that they recruited additional brain regions associated with motor and cognitive task control, working memory, and object recognition.
“Their behaviour looked similar, but the brains of the participants with OCD recruited more brain regions than the people in the control group,” Doyle said.
Some of the regions involved had not previously been associated with OCD, including the middle temporal gyrus, which supports working memory, semantic memory retrieval, and language processing, as well as an area spanning part of the occipital gyrus and the temporo-occipital junction, which is involved in lower-level visual stimulus processing and object recognition.
Study co-author Nicole McLaughlin, an associate professor of psychiatry and human behaviour at Brown and a neuropsychologist at Butler Hospital, said the findings may have implications for treatment.
Transcranial magnetic stimulation (TMS), approved by the US Food and Drug Administration in 2018 for OCD, uses magnetic pulses to stimulate targeted brain regions. Existing research shows it improves symptoms in about 30 to 40 percent of patients.
“If we reposition coils during TMS treatments to be near these brain regions, we might end up seeing a greater improvement in symptoms,” McLaughlin said.
Desrochers noted that many clinical tasks are static, whereas daily life requires organising information and making decisions in sequences that engage multiple control systems.
“A lot of tasks that are used in a clinical setting are static,” said Desrochers. “But as humans, we interact with the world through sequences, where we organise information and make decisions. So we’re asking people to do a task where these different control systems have to interact.”
“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 added.
The researchers are also exploring the sequencing task as a potential assessment tool. “We are planning to use the task between treatments,” McLaughlin said. “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.”
The research was funded by the National Institute of Mental Health and the National Institute of General Medical Sciences.