How trauma changes the brain
Abstract: Researchers are finding that changes in the brain’s saliency 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 change our brains. But these changes do not occur because of physical injury; instead, the brain seems to rewire itself after those experiences.
Understanding the mechanisms involved in these changes and how the brain learns about the environment and predicts threats and safety is the focus of the ZVR laboratory at the University of Rochester’s Del Monte Neuroscience Institute, led by Assistant Professor Benjamin Suarez-Jimenez, Ph.D.
“We are learning more about how people exposed to trauma learn to distinguish what is safe from what is not. Their brains give us insight into what might go wrong in the specific mechanisms affected by trauma exposure, especially when emotions are involved,” said Suarez-Jimenez, who began this work as a postdoctoral fellow in Yuval Neria’s lab. , Ph.D., professor at Columbia University Irving Medical Center.
Their 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 psychopathology, including PTSD, depression, and anxiety).
Using fMRI, the researchers recorded activity in the participants’ brains as they looked at 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—this one within the trauma-exposed resilient group.
They found that the brains of trauma-exposed people without psychopathology compensated for changes in their brain processes by turning on the executive control network — one of the dominant networks in the brain.
“Knowing what to look for in the brain when someone is exposed to trauma could significantly improve treatment,” said first author Suarez-Jimenez, Ph.D. Xi Zhuom, an assistant professor of clinical neurobiology at Columbia, wrote the paper. “In this case, we know where the change occurs in the brain and how some people can bypass that change. It is an indication of resilience.”
Adding an element of emotion
The possibility of a threat can change the way someone exposed to trauma responds. Researchers have found this to be the case in people with post-traumatic stress disorder (PTSD), as described in a recent study in Depression and anxiety. Suarez-Jimenez, his fellow co-authors and senior author Neria found that PTSD patients could perform the same task as someone without trauma exposure when no emotions were involved.
However, when threat-induced emotions were added to a similar task, those with PTSD had more difficulty distinguishing the differences.
The team used the same methods as the other experiment – different sizes of circles with one size associated with a threat in the form of a shock. Using fMRI, the researchers noticed that people with PTSD had less signal between the hippocampus (an area of the brain responsible for emotion and memory) and the salience network (a mechanism used for learning and survival).
They also found less signaling between the amygdala (another area associated with emotion) and the default mode network (an area of the brain that is activated when one is not focused on the outside world). These findings reflect the inability of a person with PTSD to effectively distinguish between circuits.
“This tells us that PTSD patients only have trouble distinguishing when there is an emotional component. In this case, aversive; we still need to confirm if this is true for other emotions like sadness, disgust, happiness, etc.,” said Suarez-Jimenez. “So it’s possible that in the real world, emotions overwhelm their cognitive ability to distinguish between safety, danger or reward. It overgeneralizes to the point of danger.”
“Taken together, the findings from both papers, derived from … a study aimed at uncovering the neural and behavioral mechanisms of trauma, PTSD and resilience, help expand our knowledge of the effect of trauma on the brain,” said Neria, lead PI on this the study.
“PTSD is driven by significant dysfunction in areas of the brain vital to fear processing and response. My lab at Columbia and Dr. Suarez-Jimenez’s lab in Rochester are committed to advancing neurobiological research that will inform the development of new and better treatments that can effectively target aberrant fear circuits.”
Suarez-Jimenez will continue to explore brain mechanisms and the different emotions associated with them using more real-life situations with the help of virtual reality in her lab. He wants to understand whether these mechanisms and changes are specific to the threat and whether they extend to context-related processes.
About this trauma and news from neuroscientific research
Original research: Open access.
“Sequential fear generalization and network connectivity in trauma-exposed humans with and without psychopathology” Xi Zhu et al. Communication biology
Sequential fear generalization and network connectivity in trauma-exposed humans with and without psychopathology
Although impaired fear generalization is known to underlie a wide range of psychopathology, the extent to which trauma exposure per se results in deficient fear generalization and its neural abnormalities remains to be studied. Similarly, the neural function of intact fear generalization in humans who have suffered trauma and have not developed significant psychopathology remains to be characterized.
Here, we use an fMRI generalization task and a network connectivity approach to elucidate putative behavioral and neural markers of trauma and resilience. The generalization task allows for longitudinal assessments of threat discrimination learning.
Participants exposed to trauma (TE; N= 62), compared to healthy controls (HC; N= 26), show less activity reduction in the salience network (SN) and right executive control network (RECN) across two sequential stages of generalization, and poorer discrimination learning in the SN as measured by linear deviation (LDS) scores.
Comparison of resilient, trauma-exposed healthy control participants (TEHC; N= 31), individuals exposed to trauma who have psychopathology (TEPG; N= 31) and HC, reveals a robust signature of network connectivity differences in the RECN during generalized learning as measured by the LDS.
These findings may indicate a trauma exposure phenotype that has the potential to advance the development of innovative treatments by targeting and engaging specific neural dysfunction among trauma-exposed individuals, across a variety of psychopathologies.