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In a groundbreaking discovery, a collaborative effort between neuroscientists Professor Yung Wing-ho from City University of Hong Kong (CityUHK) and Professor Ke Ya from The Chinese University of Hong Kong (CUHK) Faculty of Medicine (CU Medicine) has confirmed the existence of discrete number sense in rats. This revelation offers a crucial animal model for investigating the neural basis of numerical ability and disability in humans. The findings have been published in the renowned multidisciplinary scientific journal Science Advances.
Number sense, a fundamental ability in animals’ perception of the world, has long been linked to survival and intelligence. It plays a pivotal role in mathematical aptitude, a hallmark of human intelligence, and affects approximately 3% to 7% of people who suffer from dyscalculia, a learning disability impacting arithmetic and mathematical skills. Dissecting the mechanisms underlying numerical ability has been a longstanding pursuit in neuroscience.
The research team employed an innovative approach, integrating a novel numerical learning task, brain manipulation techniques, and artificial intelligence modeling to resolve an ongoing argument about whether rats possess a sense of numbers. Their study sheds light on the mechanisms underlying numerical ability and provides insights into the neural circuits involved in number processing in animals.
Number sense, distinguished from associated magnitudes, involves the capability to compare, estimate, and manipulate nonsymbolic numerical quantities. Overcoming challenges in isolating number sense from continuous magnitudes, the researchers developed an algorithm to generate stimuli focusing solely on numbers, facilitating a deeper understanding of how animals perceive and quantify numbers.
Remarkably, the study found that rats, previously unexposed to numerical concepts, could develop a sense of numbers when trained with sounds representing different numerical quantities. Despite the presence of continuous magnitudes, the rats consistently prioritized the number of sounds when making choices for food rewards.
Professor Yung Wing-ho, Associate Dean of the Jockey Club College of Veterinary Medicine and Life Sciences at CityUHK, remarked, “Our study elucidates the intricate relationship between magnitude and numerosity processing. By blocking a specific part of the rats’ brain, the posterior parietal cortex, we observed a selective impairment in their ability to understand numbers while their sense of magnitude remained unaffected. This suggests the existence of a dedicated brain area for numerical processing.”
Professor Ke Ya from CU Medicine expressed excitement about the implications of the findings. “This study not only demystifies how brains handle numbers but also provides new insights into the specific neural circuits involved in number processing in animals and the genetic underpinnings of mathematical ability,” she noted. “Furthermore, the neural network modeling employed in our research holds promise for applications in artificial intelligence. Understanding the brain mechanisms governing number processing may pave the way for interventions for individuals with numerical difficulties.”
Professor Yung and Professor Ke serve as corresponding authors, with Dr. Liang Tuo, Dr. Peng Rongchao, Mr. Rong Kanglin, and Ms. Li Jiaxin from CUHK contributing to the research. Their collaborative effort marks a significant milestone in understanding the foundations of numerical cognition, with implications spanning neuroscience, psychology, and artificial intelligence.
