Summary: A new study combines rodent circuitry mapping with ultra-high-field 7T human fMRI to investigate periaqueductal gray (PAG) regulation. By identifying the upstream brain regions that govern this core midbrain defensive command center, the project aims to develop real-time fMRI neurofeedback therapies that enable patients with PTSD and anxiety disorders to consciously regulate their chronic hyper-arousal states.
Key Facts
- The Periaqueductal Gray (PAG) Epicenter: Tucked deep inside the midbrain surrounding the cerebral aqueduct, the PAG acts as the primary command station for mammalian defensive maneuvers (fight, flight, or freeze). In PTSD and anxiety disorders, the PAG functions like an unmonitored engine, running continuously without its normal regulatory brakes.
- The Indirect Targeting Strategy: Because the PAG is exceptionally tiny and buried deep within the brain stem, directly modulating it is difficult. Instead, the alliance is mapping the higher-order cortical and subcortical brain regions that regulate and send inhibitory signals to the PAG. These upstream regulatory areas serve as optimal targets for therapeutic intervention.
- The Rodent-to-Human Translation Loop:
- Amsterdam (NIN): Researchers use high-precision tools (like optogenetics and calcium imaging) in mice to identify the precise cellular connections and circuits that drive fear extinction and stress control.
- Maastricht (UMC): Human imaging teams use 7T fMRI to immediately verify whether these exact same neural pathways are structurally active and functioning in humans.
- Real-Time Neurofeedback: The ultimate goal is to build custom fMRI neurofeedback protocols. Under this paradigm, patients inside a 7T scanner receive real-time visual displays of their own upstream threat-network activity, gradually training their minds to consciously dampen overactive threat responses.
- Structural Educational Mission: Beyond engineering new therapies, the alliance is actively integrating this dual-focus circuit data directly into the training curricula for early-career psychiatrists, psychologists, and clinical researchers, ensuring future clinicians understand the biological wiring behind fear.
Source: KNAW
Why does the brain’s stress system remain stuck in overdrive for some people?
Researchers at the Netherlands Institute for Neuroscience (NIN) and Maastricht UMC are joining forces to find the answer. By combining fundamental neuroscience with clinical research, they aim to better understand how the brain regulates stress and lay the groundwork for new treatments for conditions such as post-traumatic stress disorder (PTSD) and anxiety disorders.
The brain’s alarm system
Everyone is familiar with the body’s automatic response to danger: your heart rate increases, your muscles tense, and your body prepares to fight, flee, or freeze. In people with stress-related or anxiety disorders, however, this alarm system often remains activated even when there is no immediate threat.
At the heart of the project is a tiny structure deep within the brainstem called the periaqueductal gray (PAG).”The PAG is essentially the control center for our defensive responses,” says neurobiologist Alexander Heimel.”But because it is so small and located deep within the brain, we are looking for the brain regions that regulate the PAG instead. These regions may be much better suited as targets for teaching people to better control their stress responses.”
From the laboratory to the clinic
To achieve this, the researchers are combining two complementary approaches. In Amsterdam, they use advanced techniques in mice to identify the brain circuits involved in fear and stress. Colleagues in Maastricht then investigate whether the same networks are involved in humans using ultra-high-field 7 Tesla MRI scanners. Ultimately, they aim to test whether people can learn to consciously influence these brain regions through neurofeedback.
During neurofeedback training, participants receive real-time feedback about their own brain activity while undergoing a functional MRI scan. They then gradually learn how to influence activity in those specific brain regions.”
A unique collaboration
The close integration of fundamental neuroscience and clinical psychiatry is what makes this project unique. “There are relatively few projects in which fundamental animal research and psychiatry work this closely together,” says Heimel. “This allows us to translate fundamental discoveries into potential clinical applications much more quickly.”
Psychiatrist David Linden believes this close collaboration is one of the project’s greatest strengths. “To develop new treatments, you first need a thorough understanding of the brain networks you want to influence. By combining fundamental neuroscience and human research from the very beginning, we are building a much stronger foundation for future therapies.”
The project also has an educational mission. The researchers intend to integrate the knowledge gained into the training of psychiatrists, psychologists, and early-career researchers. “It is important that future mental health professionals not only know how to treat patients, but also understand the brain circuits that underlie fear and stress,” says Linden. “This fundamental knowledge helps us better understand our patients and supports the development of new therapies.”
Key Questions Answered:
A: The periaqueductal gray (PAG) is an ancient, highly conserved structure located deep within the midbrain of the brainstem. It serves as the master switchboard for survival, coordinating immediate physical defensive responses like freezing in place or fleeing from danger. In a healthy brain, the PAG is carefully regulated by higher-level reasoning centers. In people with PTSD, these regulatory brakes fail, leaving the PAG continuously active and keeping the individual locked in a state of hyper-vigilance and distress even when there is no threat present.
A: Most standard diagnostic scanners in hospitals operate at 1.5 or 3 Tesla magnetic field strengths. While excellent for mapping general brain anatomy, their resolution is too coarse to clearly visualize tiny, deeply buried structures like the periaqueductal gray and its regulatory loops. By employing ultra-high-field 7 Tesla (7T) scanners, the Maastricht team can achieve unparalleled spatial resolution, allowing them to observe fine-grained activity patterns inside the deep brain stem of awake, active human participants.
A: Think of neurofeedback like a digital mirror for your brain’s internal activity. While lying inside an fMRI scanner, patients are shown a visual representation (such as a thermometer or a sliding bar) of the current activity level in their brain’s upstream stress-regulation networks. By trial and error, guided by cognitive strategies, patients learn how to adjust that bar. Over repeated sessions, this real-time feedback allows them to strengthen the inhibitory connections that calm the brain’s survival alarm, training the brain to regulate stress more effectively.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this PTSD and neuroscience research news
Author: Eline Feenstra
Source: KNAW
Contact: Eline Feenstra – KNAW
Image: The image is credited to Neuroscience News
