Bernstein member involved: Michael Wibral

“Resilience is the ability to maintain good mental health in the long term despite adverse circumstances. By understanding how it works neurobiologically, we can address it more effectively and develop new strategies to prevent and treat stress-related mental health conditions,” explains Professor Oliver Tüscher, the last author of the study, associate research group leader at LIR, and Department of Psychiatry, Psychotherapy and Psychosomatic Medicine at University Medicine Halle.

Professor Albrecht Stroh, co-last author of the study, associate research group leader at LIR and Director of the Institute of Physiology I at University Hospital Münster emphasizes that “Resilience is often measured by how a person behaves. However, this is ultimately determined by neurobiological processes in the brain. Even though several connections have already been identified at the molecular, cellular and regional level, little is known about the interaction between brain networks.”

Interaction between regions of the brain linked to resilience

To examine the mechanisms of resilience more closely, the research team first assessed the mental well-being of 103 study participants and identified any stressful life events they had experienced in recent months. Using this data, they derived an individual resilience score. The participants then took part in an extensive series of experiments in which they were shown emotional images before undergoing a visual behavioral analysis test. At the same time, electroencephalography (EEG) was used to monitor their brain activity.

The findings: Resilient people completed the tasks more quickly and made fewer mistakes. Their brain regions worked together in a more organized way. The EEGs showed evidence of greater control through the frontal lobe, i.e. the part of the brain that is responsible for control and decision-making. At the same time, the activity in the brain’s visual cortex was less random and disorganized.

Resilient mice also process visual stimuli more accurately

To investigate these relationships in greater detail and at the single-cell level, the researchers conducted a similar test on mice. Here, some animals were subjected to repeated social stress by experiencing brief confrontations with an aggressive mouse. They exhibited resilient social behavior if, after a period of rest, the stressed animals were still willing to interact with a novel mouse. Just like the humans, some of the stressed animals were resilient in this sense, while others were less so.

Other mice underwent the same procedure but did not experience social stress. These non-stressed animals exhibited normal social behavior. Afterward, all mice – both stressed and non-stressed – were exposed to visual stimuli, while the activity of the individual neurons in the visual cortex of their brains was observed.

The findings were consistent with those of the human participants: Resilient mice – stressed animals that exhibited normal social behaviour – were found to have less spontaneous, disorganized activity in their visual cortex. At the same time, they were able to more accurately distinguish between visual stimuli. In contrast, less resilient animals exhibited more spontaneous neuronal activity and were less accurate at the task.

Resilience is an active process in the brain and can be trained in mice

“Interestingly, the non-stressed animals in this experiment exhibited similar patterns of neuronal activity as the stressed, non-resilient animals. In the resilient mice, however, it was the social stress in the experiment that led to active changes in the brain which increased their resilience. They performed better at processing visual information,” explains Professor Stroh. The findings in mice demonstrate that stress can be cognitively beneficial under certain conditions. However, sweeping statements cannot yet be made about what the ideal conditions for this are.

The brain’s adaptability is reflected by its ability to actively remodel its structure, functions and connections in response to experiences, injuries, or stress. Experts refer to this as plasticity. “Our study is the first of its kind to show that plasticity of the brain’s visual circuits is a mechanism of resilience. By studying the mice, we were also able to prove for the first time that these were active, measurable neurobiological changes in visual and prefrontal brain areas,” concludes Professor Tüscher.

The study was funded by the German Research Foundation (DFG), the Japan Science and Technology Agency’s Moonshot Research and Development Program, the Leibniz Association, the Volkswagen Foundation, and the Federal Ministry of Research, Technology, and Space within the framework of the German Center for Mental Health.