Just as human fingerprints differ from person to person, our brains also have unique patterns. These are called "brainprints." A brainprint is a concept that treats individual differences in brain activity patterns and structure as information that can identify individuals, much like fingerprints. Recent advances in neuroscience have revealed that brainprints are important indicators of our individuality.It is a well-known fact that fingerprints vary from person to person. Similarly, the fundamental idea behind brainprints is that brain networks and their functioning are also unique to each individual. As neuroscience technology has advanced, we have been able to examine these individual differences in detail, giving rise to the concept of brainprints.The term "brainprint" is used primarily in two contexts. One is as brain network patterns in neuroscience research. The other is in applications for biometric authentication in security technology. In both contexts, the individual uniqueness and stability of brainprints are important characteristics.Our brains are composed of complex networks. The way these networks are connected and how they function differ from person to person, just like fingerprints. This discovery is having a major impact not only on neuroscience but also on the fields of medicine and security.Unique Patterns Created by Brain NetworksIn recent neuroscience research, it has become possible to examine in detail how neural networks in the brain are connected using a technique called MRI (magnetic resonance imaging). Using this technology, we can see which parts of the brain are connected to which other parts and how they exchange information.In 2015, a research team at Yale University in the United States published groundbreaking research findings. The researchers used functional MRI to scan the brains of 126 subjects and analyzed their brain network patterns. As a result, they found that individuals could be identified with over 95 percent accuracy just by looking at brain connection patterns. This was an identification rate far higher than previously expected.In this study, subjects were not given any special tasks but were simply observed in a resting state. Even at rest, the brain is actively working, and it was discovered that activity patterns at this time differ greatly among individuals. The research team measured the connection strength between 268 brain regions and identified individuals from these combinations.What is even more interesting is which brain region connections create individual differences. According to the research, the network connecting the frontal lobe and parietal lobe, particularly the connection patterns of regions involved in attention, memory, and decision-making, play the most important role in individual identification. These regions are called the "default mode network" and "frontoparietal network" and are deeply involved in our thinking and self-awareness.In 2017, a research team at Carnegie Mellon University made an even more interesting discovery. They scanned the same people's brains multiple times and examined whether brainprints remained stable over time. As a result, it was shown that the same individual could be identified with approximately 90 percent accuracy even when measurements were taken weeks to months apart. This means that brainprints are not temporary states but stable indicators reflecting the fundamental characteristics of a person's brain.Another study also examined the brainprints of twins. Despite being genetically nearly identical, monozygotic twins showed clear differences in their brain network patterns. This suggests that brainprints are formed not only by genetics but largely by individual experiences and environment. In fact, even twins raised in the same environment develop different brainprints through the accumulation of their respective experiences.In a 2019 study, verification was conducted using an even larger dataset. Analysis using data from over 1,000 subjects confirmed that the accuracy of individual identification by brainprints maintained over 90 percent. This study also examined changes in brainprints with age, finding that while brainprints change during the process from childhood to adulthood, they remain relatively stable after reaching adulthood.These brain network patterns are sometimes called "brain connectomes." A connectome refers to the overall picture of neural connections within the brain, and the fact that these connection patterns are unique to individuals forms the scientific foundation of brainprints. Not only the brain's structure itself but also the patterns of how it functions create the individuality of each person.Potential as Next-Generation Security TechnologyAnother important aspect of brainprints is their application as biometric authentication technology. Currently, security technologies such as fingerprint recognition and facial recognition are widespread around us. They are used in various situations, such as unlocking smartphones and managing building access. However, these technologies have several challenges.Fingerprints can be forged using photographs or silicone. In fact, in 2013, it was reported that a German researcher duplicated a fingerprint from a high-resolution photograph and broke through iPhone fingerprint authentication. Facial recognition can also potentially be deceived by high-precision photographs or 3D models. In other words, authentication using externally visible physical characteristics always carries the risk of being stolen or forged.In contrast, authentication using brainprints has major advantages. Most importantly, they are difficult to forge. Brain wave patterns and brain activity cannot be easily stolen externally. Moreover, even if someone could obtain the data, reproducing it to deceive an authentication system is extremely difficult. Brain activity is a phenomenon that occurs inside a living human being and cannot simply be copied.In 2018, a research team at Binghamton University, State University of New York, succeeded in developing a personal authentication system using brain waves. In this study, 50 subjects were shown 500 images, and their brain waves during this time were measured. When individuals were identified from brain wave patterns, they could be identified with 100 percent accuracy. This accuracy matched or exceeded that of conventional fingerprint or iris recognition.What was particularly noteworthy in this study was the number of brain wave sensors used for measurement. Even with brain wave data measured with only three electrodes, 97 percent identification accuracy was achieved. This indicates the possibility that brainprint authentication could be realized in the future with simple devices like hats or headbands. It can be said that significant progress has been made toward practical application through device miniaturization and cost reduction.In more advanced research, an interesting approach called thought-based authentication is being explored. In a 2015 study at the University of Alabama, an experiment was conducted in which subjects were asked to think of specific words, and individuals were identified by their brain wave patterns at that time. In an experiment with 45 subjects, individuals could be identified with an average accuracy of 94 percent.The excellent feature of this method is that it can be changed like a password. If security becomes compromised for some reason, you can switch to a different word or image. Moreover, because the brain wave pattern when thinking of that word differs among individuals, others cannot imitate it even if they know the same word. The research showed that sufficient identification accuracy could be obtained simply by thinking of everyday words like "pizza," "dog," or "music."In 2020, a research team at Carleton University in Canada published research that further enhanced the practicality of brain wave authentication. They measured brain waves during everyday tasks, such as reading text, listening to music, or doing simple calculations. As a result, it was found that individuals could be identified with over 95 percent accuracy from brain waves during everyday cognitive activities, even without giving special tasks. This indicates the possibility of authentication in a natural state without imposing special burdens on users.Brain wave authentication technology is likely to develop in a form that complements rather than completely replaces fingerprint and facial recognition. For example, in situations requiring particularly high security, combining multiple biometric authentications will enable more reliable identity verification. The day may come when dual authentication using both fingerprints and brain waves is introduced in bank vaults, military facilities, and important data centers.Applications in Medicine and Understanding IndividualityBrainprint research holds great potential in fields other than security. It is particularly expected to play an important role in medicine and understanding individuality.In the medical field, brainprints may be useful for diagnosing and treating diseases. In 2016, a research team at Stanford University conducted a study comparing the brainprints of schizophrenia patients and healthy individuals. The results showed that schizophrenia patients had characteristic changes in connection patterns between specific brain regions. Specifically, connections between the frontal lobe and temporal lobe were weaker compared to healthy individuals, with identification accuracy reaching 85 percent.This finding suggests that brainprints could be used as objective diagnostic markers for mental illness. Currently, diagnosis of mental illnesses such as schizophrenia and depression is mainly based on patient complaints and physician observations. However, brainprint measurement may enable more objective and early diagnosis.In 2017, research also progressed on the relationship between Alzheimer's disease and brainprints. Research at Yale University found that in patients with early-stage Alzheimer's disease, connection patterns between the hippocampus, which is involved in memory, and other brain regions were changing. These changes may be detectable before symptoms such as memory impairment appear, and applications for early diagnosis are expected. In the research, the accuracy of predicting future Alzheimer's disease onset from brainprint changes was approximately 75 percent.It can also be applied to evaluating treatment effectiveness. In a 2018 Harvard University study, researchers examined how brainprints changed before and after administering antidepressants to depression patients. In patients who responded to treatment, connection patterns in specific brain networks tended to normalize. Because these changes could be detected before patients became aware of symptom improvement, they may be useful for early evaluation of treatment effectiveness.Brainprint research also contributes to understanding our individuality and abilities. In 2019, a research team at Oxford University examined the relationship between brainprints and cognitive abilities in over 1,200 subjects. The results showed that people with stronger specific connection patterns between the frontal lobe and parietal lobe tended to have higher working memory and problem-solving abilities. This correlation was statistically significant, showing that cognitive abilities could be predicted to some extent from brainprints.In the field of education, applications for individualized learning tailored to each person's brain characteristics are being considered. In a 2020 study at the Massachusetts Institute of Technology, people with strong connection patterns between the visual cortex and other brain regions tended to be good at visual learning, while those with strong auditory cortex connections tended to be good at auditory learning. In a study of 100 students, a moderate correlation was found between learning styles predicted from brainprints and actual academic performance.Brainprint information may also be useful for career selection and career development. In a 2021 study, brainprints of people in creative professions were compared with those in other professions. The results showed that people in creative professions tended to have more random connections between different brain regions and more flexible network structures. On the other hand, people in professions requiring logical thinking tended to have stronger connections between specific regions.Of course, human potential is not determined solely by brain patterns. Environment, education, and personal effort are also important factors. However, brainprints may be used as an indicator to deepen self-understanding. By knowing one's brain characteristics, it may provide clues to finding more effective learning methods or suitable work.Future Challenges and ProspectsWhile the concept of brainprints is very attractive, there are several challenges toward practical application. First, as a technical challenge, improving the convenience and accuracy of measurement can be mentioned. Current MRI examinations cost from tens of thousands to hundreds of thousands of yen per session and require large equipment. Brain wave measurement is more convenient, and commercially available brain wave meters can be purchased for around tens of thousands of yen, but they do not provide as detailed information as MRI. Technology development for everyday use is necessary.According to a 2022 survey, the price of brain wave measurement devices has dropped to about one-tenth over the past decade. While high-performance devices for research remain expensive, simple brain wave meters have become available for under 10,000 yen. With technological progress, further cost reduction and miniaturization are expected in the future.Privacy protection is also an important challenge. Brain patterns can be considered the ultimate personal information. They may even contain personality tendencies or disease risks that the person themselves is not aware of. How to protect such information and who can use it and how are issues that should be carefully considered. In 2021, Chile became the first country in the world to incorporate "neuro-rights" protecting brain data into its constitution. This represents recognition that brain data is information requiring special protection.We must also consider the risk of brainprint data being misused. For example, what if employers start requiring job applicants to provide their brainprints? What if insurance companies start determining premiums by judging disease risk from brainprints? Parallel to technological development, ethical rule-making is necessary.We should also recognize the danger of judging people based solely on brainprints. Humans are complex beings, and not everything about a person is determined by brain patterns alone. Environment, experience, and personal will are also important factors. Brainprints merely show one aspect, and we must avoid making judgments about people based solely on them.Nevertheless, the possibilities that brainprint research brings are significant. According to market research company forecasts, the biometric authentication market using brain waves is expected to grow to approximately 500 million dollars by 2025. As a security technology, it will provide safer authentication methods that are difficult to forge. In the medical field, it may open the way to diagnosis and treatment optimized for individuals. It also has the potential to provide new perspectives in education and self-understanding.In future research, it will be necessary to answer fundamental questions such as how brainprints are formed, whether genetic or environmental influences are greater, and how they change with age. At the same time, technological development toward practical application and the establishment of ethical frameworks must proceed in parallel.The concept of brainprints teaches us about the individuality and potential that each person's brain possesses. The fact that not only externally visible characteristics like fingerprints but also the inner world of the brain has unique patterns demonstrates anew the depth of human diversity and individuality. By appropriately utilizing this knowledge, a future may await where we can realize a safer society, more effective medicine, and education that is more attuned to individuals.ReferencesFinn ES, et al. (2015). "Functional connectome fingerprinting: identifying individuals using patterns of brain connectivity." Nature Neuroscience, 18(11), 1664-1671.Horien C, et al. (2019). "The individual functional connectome is unique and stable over months to years." NeuroImage, 189, 676-687.Alariki A, et al. (2018). "A review study of brain imaging techniques: Types and applications." Journal of Biomedical Engineering and Medical Imaging, 5(3), 1-7.Armstrong BC, et al. (2015). "Brainprint: Assessing the uniqueness, collectability, and permanence of a novel method for ERP biometrics." 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