Summary: Getting dressed in the morning seems like a simple sequence, but for those with obsessive-compulsive disorder (OCD), the brain may be working overtime just to keep from “getting stuck.” A new study reveals that while people with OCD can perform sequential tasks as well as anyone else, their brains recruit significantly more regions to do so.
Researchers discovered high activity in areas previously unlinked to OCD—such as the middle temporal gyrus and the temporo-occipital junction—suggesting a “compensation” effect. These findings offer exciting new targets for brain stimulation therapies like TMS, which could make treatment more effective for millions.
Key Facts
- The Performance Paradox: People with OCD performed sequential cognitive tasks (like naming colors/shapes in a specific order) just as accurately as the control group, but their brain scans showed a much higher “neural cost.”
- New Brain Targets: Regions involved in working memory, language processing, and visual object recognition—previously unlinked to OCD—were found to be hyperactive during sequencing.
- Abstract Sequencing: The study focused on how we organize complex, multi-step behaviors, which is a core area where OCD symptoms, like repetitive actions, often manifest.
- TMS Potential: Repositioning magnetic stimulation (TMS) coils to target these newly identified regions could improve the current 30-40% success rate of the therapy.
- Task as Assessment: Researchers hope to use the specific sequencing task as a tool to measure if treatments are working, by seeing if the patient’s brain activity starts to look more like the “control” group.
Source: Brown University
A new study revealed that certain brain regions are more active in people with obsessive-compulsive disorder (OCD) during cognitively demanding tasks. The findings could help inform new ways in which the condition is treated and assessed.
The study, published in Imaging Neuroscience, was conducted by researchers in the laboratory of Theresa Desrochers, an associate professor of brain science and of psychiatry and human behavior at Brown University’s Carney Institute for Brain Science.
Desrochers studies abstract sequential behavior, which is behavior — such as getting dressed in the morning — that follows a general sequence even though individual steps may vary.
For the study, the team examined potential links between abstract sequencing and OCD, a prevalent psychiatric disorder characterized by repetitive thoughts and associated compulsive actions that cause distress for the diagnosed person.
“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.
For the study, researchers asked participants to perform a sequential cognitive task while in a magnetic resonance imaging (MRI) scanner, naming the color or shape of an object in a specific order.
Doyle found that while individuals 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 said.
She noted that some of the regions hadn’t previously been linked to OCD. Those regions include the middle temporal gyrus — involved in working memory, semantic memory retrieval and language processing — and 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 behavior at Brown and a neuropsychologist at Butler Hospital, said the findings may lead to new treatment targets for OCD, especially when involving transcranial magnetic stimulation (TMS).
TMS is a therapy that uses magnetic pulses to stimulate brain regions implicated in a psychiatric disorder. The procedure was approved as a treatment for OCD by the U.S. Food and Drug Administration in 2018; research has shown TMS leads to improvement in about 30-40% of OCD patients.
According to McLaughlin, the treatment might be even more effective if the newly implicated regions are targeted: “If we reposition coils during TMS treatments to be near these brain regions, we might end up seeing a greater improvement in symptoms,” she said.
The real-life relevance of the cognitive task used in the study was key to the team’s insights.
“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 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 said.
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 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.”
Funding: The research was funded by the National Institute of Mental Health (R01MH131615) and the National Institute of General Medical Sciences (P20GM130452).
Key Questions Answered:
A: It shows that the brain is essentially “redlining” to stay on track. This extra effort may be what leads to the mental fatigue and distress associated with OCD. It’s like a car needing twice the fuel to travel the same distance as another.
A: Currently, FDA-approved brain stimulation (TMS) only targets specific, well-known areas. This study gives doctors a new map. By targeting the middle temporal gyrus or visual processing centers, they may be able to help the 60% of patients who don’t see results with current methods.
A: It’s the “recipe” for daily life—like the sequence of making coffee or getting ready for work. For someone with OCD, the brain might lose its place in that sequence, leading to the urge to repeat a step over and over.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this OCD and neuroscience research news
Author: Corrie Pikul
Source: Brown University
Contact: Corrie Pikul – Brown University
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Cognitive sequences in obsessive-compulsive disorder are supported by frontal cortex ramping activity” by Hannah Doyle, Nicole C.R. McLaughlin, Sarah L. Garnaat, and Theresa M. Desrochers. Imaging Neuroscience
DOI:10.1162/IMAG.a.1084
Abstract
Cognitive sequences in obsessive-compulsive disorder are supported by frontal cortex ramping activity
Completing sequences is a routine part of daily life. Many are abstract, defined by a rule governing the order rather than the identity of individual steps (e.g., getting dressed). In obsessive-compulsive disorder (OCD), excessive ritualistic behaviors suggest a disruption in abstract sequence completion.
Executing abstract sequences requires at least two levels in a hierarchy of cognitive control: abstract sequential control (tracking steps) and task switching (shifting between tasks). While task switching has been studied in OCD, little is known in a sequential context.
Understanding both hierarchical control types is key to uncovering how abstract sequences with nested task switches are processed in OCD. Previous studies showed that the rostrolateral prefrontal cortex (RLPFC) supports abstract sequence monitoring in healthy individuals with an increase in activity across each sequence, a dynamic known as “ramping”.
Ramping outside the RLPFC is potentially indicative of other sequence-related processes such as progress toward a goal and increasing working memory load. Therefore, we hypothesized that abstract sequential control deficits would correspond to altered ramping dynamics in RLPFC and other cortical regions.
Second, we predicted task switching deficits in OCD, coupled with altered activity in cortical regions canonically implicated in task level control. We found partial support for both hypotheses.
Abstract sequential control did not show behavioral differences in OCD but did show increased overall ramping in the anterior cingulate cortex (ACC) and superior frontal sulcus (SFS) and ramping differences in additional, novel cortical regions according to abstract sequence complexity.
In contrast, behavioral differences were observed for task switching in OCD without neural differences between the groups. Together, these results suggest a group of areas support sequential control differentially in OCD than in healthy controls, despite behavioral similarity, and that this observation is likely not the result of neural deficits in task switching.
These findings, thus, provide insight into OCD during complex behaviors more similar to daily life where sequence and task level control are intertwined and may inform future potential treatment.
