Friend Or Foe? One Bundle Of Brain Fibres Let You Know (Mind and Body / Brain / Neuroscience)

New research identifies three key components to the brain’s rapid processing of emotions. It’s what lets us quickly recognize a potential friend or foe, an ability essential to survival.

The work may offer insights into disorders such as anxiety and psychosis.

Researchers were able to link a bundle of fibers deep within the brain to human social behavior for the first time.

The fiber bundle, called the stria terminalis, was involved in fast emotion processing in threatening social situations, says lead author, Ilvana Dzafic of the University of Queensland’s Queensland Brain Institute.

“People with psychotic and anxiety disorders have an altered stria terminalis pathway,” says Dzafic, who is now based at the University of Melbourne. “Our discovery may explain the link between these disorders and deficits in emotion processing, and also potentially inform treatment targets.

“People with psychosis may perceive threat from others when it is not there, while those with anxiety and post-traumatic stress disorder may have an abnormally high anticipation of threat.”

To create a realistic simulation of dynamic emotion, researchers showed videos of an actor portraying either happy or angry emotions to 46 healthy male volunteers while they underwent MRI scans.

The research identifies two other brain pathways. One of these is a region of the brain within the temporal lobes called the amygdala; the other is an attention network connected to the temporoparietal junction, an area of the brain involved in re-orienting attention.

The team found that the brain networks that helped to recognize emotion changed depending on whether the participant was expecting to see the emotion with which they were presented.

“The amygdala network facilitated fast recognition of anger when people expected a threat, whereas the attention network was important for recognizing unexpected threats,” says Dzafic.

Researchers say the next step is to expand the research to include female volunteers, as the stria terminalis structure is different in males and females.

Dzafic will also examine people with threat-induced anxiety to understand if the stria terminalis is important during learning in stressful situations, work that associate professor Marta Garrido of the University of Melbourne will lead.

The findings of the study appear in the journal Human Brain Mapping. The Australian Research Council funded the study.

References: (1) https://onlinelibrary.wiley.com/doi/full/10.1002/hbm.24779 (2) https://journals.sagepub.com/doi/10.1177/0956797615583804 (3) https://www.nature.com/articles/s41537-019-0077-9 (4) https://www.sciencedirect.com/science/article/abs/pii/S0165032719303593?via%3Dihub

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