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Summary: Researchers are discovering that changes in the brain’s extraordinarily large network occur when a person experiences trauma.
Source: University of Rochester
Exposure to trauma can be life-changing — and researchers are learning more about how traumatic events can physically alter our brains. But these changes don’t happen because of physical injury; Rather, the brain seems to rewire itself after these experiences.
Understanding the mechanisms involved in these changes and how the brain learns about an environment and predicts threats and security is a focus of the ZVR Lab at the Del Monte Institute for Neuroscience at the University of Rochester, led by Assistant Professor Benjamin Suarez-Jimenez , Ph.D.
“We’re learning more about how people exposed to trauma learn to discern what’s safe and what’s not. Your brain gives us insight into what might go wrong in certain mechanisms that are affected by trauma, particularly when emotions are involved,” said Suarez-Jimenez, who began this work as a postdoctoral researcher in Yuval Neria’s lab, Ph.D. , Professor at Columbia University Irving Medical Center.
Her research, recently published in communication biologyidentified changes in the salience network – a mechanism in the brain used for learning and survival – in people exposed to trauma (with and without psychopathologies, including PTSD, depression and anxiety).
Using fMRI, the researchers recorded activity in the participants’ brains as they viewed circles of different sizes – only one size was associated with a small shock (or threat). Along with the changes in the salience network, the researchers found another difference – within the trauma-exposed resilient group.
They found that the brains of people exposed to trauma without psychopathologies compensated for changes in their brain processes by activating the executive control network — one of the brain’s dominant networks.
“Knowing what to look for in the brain when someone is experiencing trauma could significantly advance treatment,” said Suarez-Jimenez, co-first author of Xi Zhu, Ph.D., assistant professor of clinical neurobiology at Columbia, plus paper. “In this case, we know where a change occurs in the brain and how some people bypass that change. It is a sign of resilience.”
Adding the emotional element
The possibility of a threat can change a person’s response when faced with trauma. Researchers found this to be the case in people with post-traumatic stress disorder (PTSD), as described in a recent study in Depression & Anxiety. Suarez-Jimenez, his fellow co-authors, and senior author Neria found that patients with PTSD can perform the same task as someone not experiencing trauma when emotions are not involved.
However, when a threat-evoked emotion was added to a similar task, those with PTSD had greater difficulty distinguishing between the differences.
The team used the same methods as the other experiment – different circle sizes, with one size being associated with a shock threat. Using fMRI, the researchers observed that people with PTSD had less signaling between the hippocampus (an area of the brain responsible for emotions and memory) and the salience network (a mechanism used for learning and survival).
They also discovered fewer signals between the amygdala (another area associated with emotions) and the default mode network (an area of the brain that gets activated when someone isn’t concentrating on the outside world). These results reflect the inability of a person with PTSD to effectively distinguish between-circle differences.
“This tells us that patients with PTSD only have trouble discriminating when there is an emotional component. In this case, aversive; We have yet to confirm if this applies to other emotions like sadness, disgust, happiness, etc.,” Suarez-Jimenez said. “So it could be that real-world emotions overload their cognitive ability to distinguish between safety, danger, and reward. It generalizes toward danger.”
“Taken together, the findings from both papers, which come from a … study aimed at uncovering neural and behavioral mechanisms of trauma, PTSD, and resilience, help advance our knowledge of how trauma affects the brain,” Neria said , Lead PI on this study.
“PTSD is driven by remarkable dysfunction in brain areas critical to fear processing and response. My lab in Columbia and the Dr. Suarez-Jimenez labs in Rochester are committed to advancing neurobiology research aimed at developing new and better treatments that can effectively target aberrant anxiety circuits.”
Suarez-Jimenez will continue to explore brain mechanisms and the various emotions associated with them by using more real-life situations in his lab using virtual reality. He wants to understand whether these mechanisms and changes are specific to a threat and whether they extend to contextual processes.
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About this news from trauma and neuroscience research
Author: press office
Source: University of Rochester
Contact: Press Office – University of Rochester
Picture: The image is in the public domain
Original research: Open access.
“Sequential fear generalization and network connectivity in traumatized people with and without psychopathology” by Xi Zhu et al. communication biology
abstract
Sequential fear generalization and network connectivity in trauma-exposed people with and without psychopathology
While defective generalization of fear is known to underlie a wide range of psychopathologies, the extent to which exposure to trauma itself leads to defective generalization of fear and its neural abnormalities remains to be explored. Similarly, the neural function of intact fear generation in people who have suffered trauma and have not developed significant psychopathology has yet to be characterized.
Here we use a generalization fMRI task and a network connectivity approach to clarify putative behavioral and neural markers of trauma and resilience. The generalization task allows for longitudinal assessments of threat discrimination learning.
Trauma-exposed participants (TE; N= 62), compared to healthy controls (HC; N= 26), show a smaller reduction in activity in the salience network (SN) and in the right executive control network (RECN) across the two sequential generalization stages and poorer discrimination learning in the SN, as measured by the linear deviation values (LDS).
Comparison of resilient, trauma-exposed healthy control participants (TEHC; N= 31), trauma-exposed persons with psychopathology (TEPG; N= 31) and HC, shows a resilience signature of network connectivity differences in the RECN during generalization learning measured by LDS.
These results may indicate a trauma exposure phenotype that has the potential to drive the development of innovative treatments by targeting and addressing specific neuronal dysfunctions in trauma-exposed individuals across diverse psychopathologies.
