Swiss study looks at how the brain learns to deal with surprises

In order to find out what exactly happens in the brain, the researchers played sequences of sounds to growing mice Keystone / Robert F. Bukaty

Different brain regions learn to deal with surprising stimuli at different times. This was shown by researchers from the University of Basel in a study on mice, which was published on Wednesday in the journal Science Advances.

How the brain’s reaction to unexpected stimuli changes as we grow has been largely unexplored until now, the University of Basel wrote in a press release.

Distinguishing unexpected stimuli from ordinary ones is an important task of our brain, the researchers explained in the study. For example, it enables us to recognise threats and keep ourselves safe.

Small children are much easier to surprise than adults. For example, they still react to the sudden appearance of their counterpart in the peek-a-boo game even after the tenth time, the university said. An adult brain, on the other hand, categorises unusual stimuli much more quickly as “uninteresting” or “important”.

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In order to find out what exactly happens in the brain, the researchers played sequences of sounds to growing mice, in which a different sound was heard at irregular intervals between identical sounds. At the same time, they carried out measurements that showed how the reactions of different brain regions to the different tones changed over time.

Experience is crucial

The study showed that the reaction of the various brain regions to the oblique tones decreased as the mice grew up. However, not in all brain regions at the same time: the brain region called colliculi inferiores no longer responded more strongly in mice at the age of 20 days than in adult mice, and in the so-called primary auditory cortex in the cerebral cortex it lasted until the 50th day of life.

In human years, this would correspond approximately to an age of early 20s, the University of Basel wrote in the press release.

The researchers also showed that experience plays a decisive role in this final stage, i.e. development in the cerebral cortex. In mice that were raised in a noise-neutral environment, the processing of unexpected sounds was delayed.

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