Twin study sheds light on hereditary brain activity

How our brains process different emotional and cognitive tasks may be underpinned by common factors, scientists from UNSW and Neuroscience Research Australia (NeuRA) are discovering.

In this latest study, published in the journal Mapping the human brainDr Haeme Park and Associate Professor Justine Gatt, who hold joint appointments at UNSW Psychology and NeuRA, examined how emotion and cognition are influenced by environment and genetics, using Functional MRI (fMRI) on twins.

“A lot of research has been done on genetic and environmental influences on brain structure,” says Dr. Park, lead author of the study. “But it’s much more difficult to understand how our brains work.”

The results revealed that the situation is extremely complex. Some emotional and cognitive tasks were partly associated with genetics, and others exclusively with environment.

But they also found that some of the same genetic and environmental factors can play a role in how the brain responds to two different tasks. For example, the analysis showed that some of the same genetic factors influence how we process fear and happiness as well as how we maintain attention.

“This study is interesting because we have a better understanding of the extent to which our life experiences modulate certain brain processes, which we have more control over, to some extent, versus your biology, which you cannot change “, explains the assistant professor. Gatt, director of the Center for Well-being, Resilience and Recovery.

“Knowing which areas of our brain function are strongly linked to our environment can help us develop personalized intervention approaches to promote better mental well-being.”

The importance of twin studies

The so-called “nature versus nurture” debate is not new.

In fact, twin studies have become a unique research tool used by geneticists and psychologists to evaluate the influence of genetics and the effect of the common environment (family) and the unique environment (the individual events that shape a person’s life on a particular trait.

“In twin studies, it is important to recruit identical and non-identical twins,” explains the assistant professor. Gatt. “Identical twins share 100 percent of their genetics and if they grow up together, they share the same environment. Whereas non-identical twins, they only have 50 percent of their genetics shared, but they also have this common environment .”

“In this study, we wanted to fill many gaps in the literature and provide a more robust and in-depth picture of how our genetic and environmental factors impact the expression of brain activity during emotional and cognitive tasks, by analyzing twins,” explains Dr. Parc.

Cognitive and emotional tasks

The newest paper is one of several findings from the TWIN-E study, which recruited 1,600 identical and non-identical twins across the country in 2009 and is led by Prof. Gatt.

A subset of the original cohort participated in this particular study, with a total of 270 adult twins.

“We place the participants on the fMRI scanner bed which is equipped with glasses that allow them to see the tasks ahead of them. Functional tasks require them to view different images, different stimuli, through the glasses,” explains the assistant professor. Gatt.

As participants completed the tasks, the fMRI machine scanned their brains to measure its activity.

The twins completed a total of five tasks. Two were related to emotional responses, such as reactions to various expressions of different faces, and the other three were associated with cognition, such as the ability to maintain attention and short-term memory.

Processing fMRI scans shows you which part of the brain lights up for different processes, and how strongly the brain is activated can be measured on a scale.

“So individuals who show a lot of activation in that region have a higher number, while those with lower activation have a smaller number. We then use these numbers to perform what we call processes of “twin modeling,” says Dr. Park. “This is where we use statistics to determine how much genetics and environment contribute to that number.”

Twin modeling results

The twin modeling methods revealed two key findings in their analysis of the results.

First, the researchers examined genetic versus environmental influence on each individual task. “We know that we use different brain networks for different processes. For example, processing a crying face or a happy face will use different regions of the brain compared to trying to remember someone’s phone number one,” explains the assistant professor. Gatt.

“But we found that for some of these networks, genetics plays a small to moderate, but significant, role. And for other processes, only the environment determines brain function.”

The second part of the analysis revealed that there were similarities in the genetic and environmental factors that underlie different tasks.

“For example, we found that the way the brain processes fear and happiness (measured in emotional tasks) and our ability to maintain attention (measured in cognitive tasks) share some genetic factors,” explains Dr. Park. . “This suggests that some common genetic features may underlie these very different processes.”

In contrast, the team also found that our ability to sustain attention and working memory have some of the same environmental contributions, suggesting that life experiences, which come from your environment, play an important role in how whose brain activity is expressed for these two elements. process.

Mental well-being and resilience

While it is clear that our genetics and life experiences are important in determining how our brains function, the puzzle is far from resolved.

“There is still so much to discover,” says Dr. Park. The current participants were already followed up more recently and performed the same tasks again after 10 years. Pr/A/Prof. Gatt, Dr. Park and their team will re-evaluate the results to see how the influences of genetics and environment on these brain processes change over time.

“All of these findings paint a complex picture of the relationship between genes and the environment that give rise to the brain activity that underlies our cognition and emotions,” explains the assistant professor. Gatt. But knowing finer details can help develop personalized intervention approaches to promote, for example, better mental well-being or reduced psychological distress.

In fact, the ongoing TWIN-E study focuses more broadly on mental well-being and resilience. “So we use this data, beyond looking at genes and environment, to predict trajectories of mental well-being and resilience over time, and to see how differences in markers such that brain function and structure could profile people who are a little more resilient or more at risk of having a mental health problem,” explains Prof. Gatt.

Understanding the extent to which our life experiences influence certain processes versus the influence of genetics is important for knowing which factors we can modify and control, which is particularly important for people with mood and anxiety disorders. anxiety, explains the assistant professor. Gatt.

“If someone tends to be more interested in negative stimuli than positive stimuli, and we know that something in the environment is contributing to that, with intervention or training, that’s potentially something we can focus and improve for the better.”