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Summary: <\/strong>Researchers discovered the first definitive neural evidence of how the brain creates and reuses abstract symbols to think creatively. The research tracks the neural substrates of \u201ccompositional generalization\u201d, the foundational cognitive ability to take familiar components and recombine them into entirely fresh ideas.<\/p>\n By observing brain cell activity in primate models during complex touchscreen tasks, investigators located this symbolic engine within the ventral premotor cortex. This discovery upends traditional views of the motor system, offering a mechanistic look at abstract thought while providing templates to optimize brain-computer interfaces (BCIs) and assess cognitive disorders.<\/p>\n Key Facts<\/strong><\/p>\n Source: <\/strong>Rockefeller University<\/p>\n If you ask a child to draw an animal that doesn\u2019t exist, they\u2019ll often cobble together components from real ones\u2014say, the body of a seal with an elephant\u2019s trunk, four octopus arms, and one lizard eye.<\/strong><\/p>\n This imaginative ability is theorized to stem from our larger capacity to learn symbolic units\u2014an arm or a leg in the aforementioned example, or perhaps a word\u2014and then envision how those symbols could be reused in a new context. Neuroscientists call this facility for recombining familiar elements into fresh ideas compositional generalization, and it is hypothesized to be key to problem solving, making sense of new situations, and creative thinking.<\/p>\n In\u00a0new research\u00a0published in\u00a0Nature<\/em>, Rockefeller University\u2019s\u00a0Laboratory of Neural Systems\u00a0has found the first evidence of the neural substrates that underlie this process. The team located it in the ventral premotor cortex, a section of the frontal lobe.<\/p>\n The region appears to act as a sort of mediator between the prefrontal cortex, where higher-level thinking such as planning occurs, and the motor cortex, which enables movement.<\/p>\n In their findings, the researchers not only illuminate fundamental properties of neural function but also see implications for improving computer-brain interfaces (BCIs) and studying brain disorders.<\/p>\n \u201cThe discovery solves a long-standing problem in cognitive neuroscience: Where do symbols\u2014the basic units of thought\u2014come from?\u201d says\u00a0Winrich Freiwald, head of the lab. \u201cIt also points to a future\u2014a near future\u2014in which we can understand thinking mechanistically.\u201d<\/p>\n Action symbols<\/strong><\/p>\n Compositional generalization is an influential hypothesis in neuroscience for explaining the wide variety of human abilities that use abstract thought to generate new ideas, including math, written and spoken language, drawing, dancing, handwriting, and musicianship. It may also characterize cognitive abilities we share with other animals, such as reasoning, object manipulation, and tool use.<\/p>\n However, there hasn\u2019t been definitive neuroscientific evidence of symbols. \u201cThe idea behind our research was, if these reusable components exist, what would their neural activity look like?\u201d says first author Lucas Tian, a postdoctoral fellow in the lab. \u201cIf there are units that are being reused in different situations, then you should be able to see that in the neural data.\u201d<\/p>\n Designing an experiment to locate such neural mechanisms, however, was no mean feat. Only humans do math, use language, or draw, and the methods currently used for measuring brain activity in humans do not have the necessary resolution to monitor the activity of nerve cells in the brain.<\/p>\n To bypass that technical limitation, Tian worked with macaque monkeys. \u201cWe wanted to develop an animal model in which we can actually observe compositionality in action in the animals\u2019 behavior while simultaneously doing neural recordings to understand how the brain might be doing this,\u201d Tian describes.<\/p>\n But he still had to confront the problem of finding a behavioral paradigm for the animals that could uncover their compositional abilities. Tian\u2019s idea was to teach them to trace simple geometric figures on touchscreens\u2014lines, squares, arcs, circles, triangles\u2014and then task them with re-creating new shapes, all while observing their brain activity through sensors. Each simple shape was considered its own discrete knowledge unit, or action symbol\u2014action<\/em>\u00a0because they had to physically execute the drawing of each one.<\/p>\n Then he built novelty into the experiment by testing how the monkeys drew new, more complex shapes. \u201cI gave them a lot of symbol variation rather than having them repeat one simple task over and over. They had to learn how to grapple with new and changing factors, which is the sort of environment you\u2019d find compositional generalization useful for,\u201d Tian describes.<\/p>\n He found that even though they could have drawn these new images by using a simple tracing strategy\u2014moving their fingers along the edges of the shapes\u2014they instead chose to recombine the symbols they had learned to create new complex combinations. This revealed that they had understood these actions as symbols\u2014building blocks for creating novel drawings.<\/p>\n Surprising activity<\/strong><\/p>\n Tian used an array of electrodes to observe hundreds of neurons across eight brain regions simultaneously throughout these activities.<\/p>\n \u201cIt was important for us to cast a wide net,\u201d he notes, \u201cbecause no one knew whether\u2014or where \u2014compositional generalization might be occurring in the brain.\u201d<\/p>\n The study found that one particular region activated as the monkeys drew: the ventral premotor cortex, an area of the frontal lobe traditionally associated with the planning and execution of movement\u2014especially hand movements. Tian and his colleagues found that the activity was not simply involved in motor execution but represented a high-level cognitive representation of the action itself.<\/p>\n \u201cWhat Lucas found forces us to re-think the role of this part of the brain,\u201d Freiwald says. \u201cIt is not simply a part of the motor system one step removed from the control of the finger, but an area that generates a sort of mental typewriter. It specifies in an abstract format the \u2018key\u2019 to press when you want to express yourself in writing, and then instructs another area to turn that key into a stroke.\u201d<\/p>\n Insights into disorders of the human brain<\/strong><\/p>\n The researchers believe their novel approach could develop into a foundational experimental paradigm that could be used in humans as well. Drawing is a widely used tool for diagnosing cognitive disorders; specific disorders result in specific drawing impairments.<\/p>\n \u201cOne possibility is that the things we learn could lead to new insights into psychiatric disorders such as schizophrenia or action-planning disorders like constructional apraxia, where people have trouble creating complex action sequences even though they understand the task at hand and retain basic motor abilities,\u201d says Tian.<\/p>\n To that end, they plan to collaborate with neurosurgeons and their patients to gather brain activity data from people who have had a procedure involving brain implants, such as for epilepsy.<\/p>\n They also see possibilities for the improvement of BCIs. \u201cKnowing how thinking works mechanistically will improve our ability to read the activity of the human brain and express it into speech or action through brain-machine interfaces, where such expression is not otherwise possible,\u201d Freiwald says.<\/p>\n Moreover, there are essential questions about cognition at play, he adds. \u201cThis is basic research on a fundamental quality of human nature\u2014thinking, which is altered in many psychiatric disorders. We conduct this work with the goal of improving the human condition.\u201d<\/p>\n A<\/strong>: When a child draws a creature that doesn\u2019t exist, they instinctively grab a seal\u2019s body, an elephant\u2019s trunk, and an octopus\u2019s arms. This ability to take familiar, separate components and recombine them to handle a brand-new situation is called compositional generalization. It is the biological framework behind language, math, art, and everything we define as human creative thinking.<\/p>\n<\/div>\n A<\/strong>: For decades, scientists thought this region was just a basic cog in the motor system meant to move your fingers. This study forces a complete rewrite of that theory. The area is actually a high-level cognitive powerhouse that holds abstract symbols. It picks out the conceptual \u201ckey\u201d you want to type to express yourself, and then passes that abstract blueprint down to the muscles to create a stroke.<\/p>\n<\/div>\n A<\/strong>: Modern Brain-Computer Interfaces (BCIs) try to read a patient\u2019s brain activity and turn it into speech or machine movement. Up until now, we didn\u2019t know the exact mechanism of how the brain structures abstract units of thought. By revealing how the brain builds and combines these symbolic building blocks in real time, engineers can design BCIs that read intent mechanistically, allowing paralyzed individuals to express themselves with unprecedented speed and fluid accuracy.<\/p>\n<\/div>\n<\/div>\n Author:\u00a0<\/strong>Katherine Fenz<\/a>\n
Key Questions Answered:<\/h3>\n
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About this neuroscience and abstract thought research news<\/h2>\n
Source:\u00a0<\/strong>Rockefeller University<\/a>
Contact:\u00a0<\/strong>Katherine Fenz \u2013 Rockefeller University
Image:\u00a0<\/strong>The image is credited to Neuroscience News<\/p>\n