[LAB Exploration] "The Brain Continues to Evolve Into Adulthood"... Discovery of Sensory Circuit Remodeling

Yonsei University and DGIST Joint Research Team

Contrary to the prevailing belief in neuroscience that sensory processing circuits in the brain are completed in childhood, new research has found that the brain continues to spontaneously remodel its circuits into adulthood, leading to even more precise sensory perception.

Professor Eunji Jung of Yonsei University Department of Biotechnology (left), Dr. Dongsu Lee of Yonsei University Department of Biotechnology, and Professor Jaewon Ko of Daegu Gyeongbuk Institute of Science and Technology (DGIST) Brain Science Department Synapse Diversity and Specificity Regulation Research Center are taking a commemorative photo. Yonsei University

On February 27, Yonsei University announced that the research team led by Professor Jeong Eunji of the Department of Biotechnology had, for the first time in the world, demonstrated through joint research with Professor Ko Jaewon’s team at the Center for Synaptic Diversity and Specificity Regulation in Neuroscience, Daegu Gyeongbuk Institute of Science and Technology (DGIST), that the brain’s "sensory checkpoint" is intricately reorganized even in adulthood.

The ability of humans to selectively process only necessary information from a complex environment is thanks to the brain’s sophisticated filtering system. Among these, the "thalamic reticular nucleus (TRN)" located in the thalamus acts as a gatekeeper, regulating external stimuli before they reach the cerebral cortex. To date, academia has generally regarded this circuit structure as immutable after a certain period in childhood.

Through a precise analysis of developmental stages in a mouse model, the joint research team found that the TRN circuit is reconstructed during the transition from adolescence to adulthood. As the mice entered adulthood, their sensitivity to certain excitatory stimuli entering the TRN decreased. As a result, their ability to distinguish fine tactile differences was actually enhanced.

The research team determined that this was not simply a result of accumulated experience. Instead, they interpreted it as a "maturation process" in which the adult brain actively adjusts its circuits to improve the efficiency of sensory information processing. Even in adulthood, the brain refines its circuits to more precisely filter out unnecessary sensory signals and retain only crucial information.

The key molecule in this process was identified as the synaptic adhesion protein "LRRTM3." LRRTM3, which is abundantly and specifically distributed in the TRN, plays a critical role in finely tuning the connections between neurons, enabling the brain to distinguish even very subtle differences. In fact, when the LRRTM3 gene was removed from the TRN in mice, the circuit refinement expected in adulthood did not sufficiently occur, and their ability to discriminate fine tactile sensations was significantly reduced.

An imbalance in sensory information processing is considered a core feature of various neuropsychiatric disorders, including autism spectrum disorder, attention-deficit hyperactivity disorder (ADHD), and schizophrenia. The research team explained that the significance of their study lies in providing a scientific basis for understanding sensory perception disorders from the perspective of "adult maturation and regulation mechanisms of sensory circuits."

By concretely demonstrating the existence of adult brain plasticity, the researchers also expect that their findings will offer important clues for discovering therapeutic targets aimed at restoring sensory perceptual function in the future.

This research was published online in the neuroscience journal "Neuron" on February 17. Lee Dongsu, PhD in Biotechnology at Yonsei University, and Han Kyunga, Professor at Chungnam National University (formerly a research professor at DGIST Department of Neuroscience), participated as co-first authors. The research was supported by the Ministry of Science and ICT, the National Research Foundation of Korea’s Leader Research Program, the Samsung Science & Technology Foundation, the Mid-Career Researcher Program, and the Sejong Fellowship.

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