HSINCHU, Taiwan, Aug. 15, 2025 — A cross-disciplinary team from Taiwan’s National Tsing Hua University (NTHU), led by Ann-Shyn Chiang (江安世), Director of the Brain Research Center; Chung-Chuan Lo (羅中泉), Professor at the Institute for Systems Neuroscience; and Ting-Kuo Lee (李定國), Distinguished Chair Professor in the Department of Physics, has revealed how fruit flies (Drosophila melanogaster) make rapid decisions to either “eat” or “escape.” Their study indicates that fruit fly brains transmit olfactory signals through a hybrid neural network, utilizing “generalist neurons” for common scents like pheromones and floral odors, and “specialist neurons” for essential food-related smells.
While it was once believed that neural connections in the fruit fly’s brain were random, Ann-Shyn Chiang’s findings show that these connections include both random elements and precise, efficient pathways termed “specialist lines,” which process more critical information. This discovery offers new insights into how insect brains compute and could pave the way for future advancements in both brain science and artificial intelligence. The research was recently published in the prominent international journal, Science Advances.
The mushroom body, situated at the core of the fruit fly’s brain, is a vital center for processing sensory information and supporting learning and memory. For the past two decades, there have been differing perspectives among scientists regarding the mushroom body’s neural connectivity. Nobel laureate Richard Axel (2004, Physiology or Medicine), after analyzing approximately 10% of the relevant neurons, concluded that the neural connections were random. Conversely, Ann-Shyn Chiang has maintained that specific patterns of connectivity might exist within the fruit fly’s brain.
Chiang, a distinguished neuroscientist and Academician of Academia Sinica, headed an NTHU research team that employed neural connectome analysis, in vivo imaging technology, and computer simulation to examine the hemibrain dataset. The team determined that the connectivity between olfactory nerves and central neurons is neither entirely random nor completely fixed, but rather a hybrid model combining both random and stereotypic characteristics. Specific neural clusters display clear preferences for connection partners, encoding different odors through both diffused and concentrated patterns, thereby balancing the sensitivity and diversity of olfactory recognition.
The fruit fly’s mushroom body functions much like a miniature central processing unit (CPU), integrating various sensory inputs to help the fruit fly make decisions in complex environments, such as avoiding dangers, locating food, or finding a mate.
The NTHU research team discovered that fruit fly olfactory neurons are categorized into two functional types: “specialists” and “generalists.” Generalist neurons react to a broad spectrum of odors—including those from food, pheromones, flowers, and trees—and broadcast signals to multiple neural circuits simultaneously, akin to a radio transmission. In contrast, specialist neurons only handle crucial odors, such as those associated with fruit. They operate more like a dedicated phone line, sending essential information directly to specific neurons.
Professor Chung-Chuan Lo, from the Institute for Systems Neuroscience, further elaborated that the fruit flies’ hybrid neural connections resemble a strong password that mixes randomness and order. Lo commented, “Just like an ideal password blends familiar words with random characters, such as adding numbers or symbols to a name, the structure may appear illogical at first, but it is both easy to recall and hard to decipher.”
Ann-Shyn Chiang noted that the identification of hybrid neural connections in fruit flies, which combine both random and orderly features, clarifies how the brain distributes and integrates information. This discovery is also anticipated to provide new insights into the treatment of neurodegenerative conditions like dementia and Parkinson’s disease, and to inspire the development and application of AI neural networks.
The primary authors of the paper are Li-Shan Cheng (鄭力珊), a master’s student from the Department of Physics, and Ching-Che Charng (強敬哲), a doctoral student in the Institute for Systems Neuroscience. The corresponding authors include Distinguished Chair Professor Ann-Shyn Chiang, Professor Chung-Chuan Lo, and Distinguished Chair Professor of the Department of Physics Ting-Kuo Lee. The NTHU research team also comprises Kuan-Lin Feng (馮冠霖), a postdoctoral researcher at the Brain Research Center, and Ruei-Huang Chen (陳瑞煌), a doctoral student at the Department of Neuroscience. Feng was responsible for studying the biology and behavior of fruit flies, while Chen utilized functional imaging experiments to observe how olfactory information is transmitted within neural networks.
Ann-Shyn Chiang indicated that Li-Shan Cheng and Ching-Che Charng spearheaded the team’s core theoretical analysis, while Ruei-Huang Chen and Kuan-Lin Feng were the scientists conducting the experimental testing. Chiang stated, “The key to deciphering the neural connectivity of fruit flies lies in combining cross-disciplinary collaboration across physics, neuroscience, and behavioral research.”
The NTHU Laboratory of Brain and Intelligence initiated this research on fruit fly neural connections in partnership with Taiwan’s China Medical University (CMU), the National Health Research Institutes, Academia Sinica, and the Kavli Institute for Brain and Mind Research at the University of California, San Diego. The project received funding from Taiwan’s Ministry of Education, the National Science and Technology Council (NSTC), and the Peng Education and Welfare Foundation.
Contact:
Holly Hsueh
NTHU
(886)3-5162006
hoyu@mx.nthu.edu.tw
Ann-Shyn Chiang (江安世, front-right), Director of the NTHU Brain Research Center, and Professor Chung-Chuan Lo (羅中泉, front-left) of the Institute for Systems Neuroscience, led a cross-disciplinary team in decoding the fruit fly’s brain. The team included Ruei-Huang Chen (陳瑞煌, from back-left), a doctoral student at NTHU’s Institute of Systems Neuroscience; Li-Shan Cheng (鄭力珊), a master’s student in NTHU’s Department of Physics; Ching-Che Charng (強敬哲), a doctoral student from the Institute of Systems Neuroscience; and Guan-Lin Feng (馮冠霖), a postdoctoral researcher at the Brain Research Center. (Photo: National Tsing Hua University)
