summary: Researchers studied mice to understand how the brain processes unexpected stimuli during development.
They found that the brain’s response to surprise changes as we grow older, becoming more efficient at categorizing stimuli as “important” or “uninteresting.” This developmental change reduces overreaction to familiar surprises and helps conserve energy.
The study also found that brain regions responsible for processing surprise matured at different rates, with the cerebral cortex maturing more slowly, similar to humans in their early 20s. Sound experience plays an important role in this development.
Important facts:
- The brain’s response to startling stimuli becomes more efficient and saves energy as we grow older.
- Different brain regions mature at different rates when processing surprise.
- Experience with sound is essential for the development of the startle response in the cerebral cortex.
sauce: University of Basel
For children, the world is full of surprises. Adults, on the other hand, are much more difficult to surprise. And behind this seemingly simple situation lies a complex process. Researchers at the University of Basel are using mice to decipher how the developing brain reacts to unexpected events.
Babies love playing peek-a-boo and keep responding even when their partner suddenly appears for the tenth time during the game. Recognizing the unexpected is an important cognitive ability. After all, new can also mean danger.
However, the exact way surprise is processed in the brain changes as we grow up. Unusual stimuli are categorized as “important” or “uninteresting” much more quickly, and the second or third time they appear, they are surprisingly less surprising.
This efficiency increase makes perfect sense. New stimuli may capture our attention, but they do not provoke unnecessarily strong reactions that consume energy. This may seem trivial at first glance, but so far there has been little research on this fact from the perspective of brain development.
Experiments in young mice by Professor Tania Barkat’s research team have begun to decipher how the developing brain processes surprising sounds, and what changes as they grow. .
The researchers reported their findings in the journal scientific progress.
strange sounds
In their experiments, the researchers used a series of tones in which different tones were heard at irregular intervals between the same tones. At the same time, the animals’ brain waves were also recorded. This process is known as the “bizarre paradigm” and is used by medical professionals for purposes such as diagnosing schizophrenia.
Using these measurements, the researchers were able to understand how the responses of different areas of the brain to tonal changes develop over time in young mice. This response was initially very strong, but decreased as the involved brain regions matured, reaching levels comparable to those measured in adult animals. However, this development does not occur simultaneously in different areas of the brain that process sound.
The area known as the inferior colliculus, located at the beginning of the pathway from the auditory nerve to the auditory cortex, was already fully mature at 20 days of age, the earliest time point studied by the researchers. The second region, the auditory thalamus, showed only “adult” responses to different tones at 30 days of age.
The cerebral cortex itself, the “primary auditory cortex,” took even longer to develop, taking until day 50.
“The development of this startle response therefore begins in the periphery and ends in the cerebral cortex,” says study leader Tania Barkat.
Therefore, the cerebral cortex matures much later than expected. In terms of human age, this is roughly equivalent to his early 20s.
No development without experience
The researchers also observed that experience plays an important role in the development of the startle response in the cerebral cortex. When mice were kept in a noise-free environment, processing of unexpected sounds in the auditory cortex was significantly delayed.
One possible explanation for this is that the brain, specifically the cerebral cortex, forms an internal image of the world during development and compares it to external stimuli. Anything that doesn’t fit into this “worldview” would be surprising, but it could also result in an update.
“But without sound experience, the cerebral cortex of these mice is unable to build such a model of the world,” says neuroscientist Burkat. As a result, animals are unable to properly classify sounds into “familiar” and “unexpected” sounds.
About this neurodevelopmental research news
author: Leto Kaluori
sauce: University of Basel
contact: Leto Kaluori – University of Basel
image: Image credited to Neuroscience News
Original research: Open access.
“Sequential maturation of stimulus-specific adaptation in the mouse lemniscal auditory system” written by Tania Barkat et al. scientific progress
abstract
Sequential maturation of stimulus-specific adaptation in the mouse lemniscal auditory system
Stimulus-specific adaptation (SSA), the suppression of neural activity to common stimuli that does not generalize to other rare stimuli, is an important property of our brains. Although well characterized in adults, it is still unclear how it develops in adolescence and what neural circuits are involved.
Using in vivo electrophysiology and optogenetics in the lemniscal pathway of the mouse auditory system, we show that SSA is stable in the inferior colliculus from postnatal day 20 (P20), in the auditory thalamus until P30, and thereafter in the primary auditory cortex. observed to develop. (A1).
We found that this maturational process is experience-dependent in A1 but not in the thalamus, and that it is associated with changes in deep but not input layers of A1. We also identified that corticothalamic projections are involved in the development of thalamic SSA.
Taken together, our results reveal different circuits underlying sequential SSA maturation and provide a unique perspective for understanding predictive coding and surprise across sensory systems.