The human brain can switch between tasks with a speed and ease that artificial intelligence still struggles to match. A new neuroscience study suggests this flexibility comes from how the brain reuses the same basic components across different situations. Instead of starting from scratch each time, the brain appears to rebuild new tasks from familiar parts.Cognitive Building Blocks in the Brain. Image by FreepikNote: This article is intended for general information and educational purposes. It summarizes scientific research in accessible language for a broad audience and is not an official scientific press release.A study published in Nature in November 2025 examines why the brain is able to switch so efficiently between different tasks. The research was conducted by Sina Tafazoli, Flora M. Bouchacourt, Adel Ardalan, Nikola T. Markov, Motoaki Uchimura, Nathaniel D. Daw, and Timothy J. Buschman at the Princeton Neuroscience Institute and the Department of Psychology, Princeton University, in collaboration with Marcelo G. Mattar from the Department of Psychology, New York University.Using neural recordings from non-human primates, the researchers investigated how the brain moves between related tasks that share common components. According to the authors, the study focuses on whether cognitive flexibility depends on reusable neural representations – described as shared “cognitive building blocks” – rather than on creating entirely new patterns of brain activity each time task demands change.What the Researchers InvestigatedThe researchers asked a simple but fundamental question: how does the brain adapt so quickly when the rules of a task change?Previous work in artificial intelligence has shown that systems trained on multiple tasks can experience interference, where learning new information affects previously learned tasks. In this study, the authors examined whether the brain relies on a different organizational principle by reusing shared internal components across tasks.In this context, these components are patterns of neural activity that represent stimulus features or actions. The key question was whether such patterns are shared across tasks and flexibly combined depending on current task demands.How the Study Was ConductedTwo monkeys were trained to perform three related categorization tasks. In each task, the animals viewed visual stimuli that varied in both color and shape. Depending on the task, they were required to judge either the color or the shape of the stimulus and indicate their decision by making an eye movement in a specific direction.The tasks were designed to share common components. Some tasks required the same type of categorization, while others shared the same response directions. Importantly, the monkeys were not informed which task was active at the start of each block and had to infer the current task based on feedback.While the animals performed the tasks, researchers recorded neural activity from multiple brain regions, including the lateral prefrontal cortex. The analysis focused on how populations of neurons represented task-relevant information and how these representations changed when the task switched.What Makes This Study NewThe authors highlight that this study provides empirical evidence that the brain can perform different tasks using shared neural components, rather than relying on entirely separate representations for each task. The findings show that patterns of neural activity are reused and flexibly combined depending on task demands.In public explanations of the study, this idea has been described using a simple analogy. As summarized by Neuroscience News, shared neural components are compared to LEGO blocks: basic cognitive elements that can be assembled and reassembled in different combinations to support different tasks. In this framing, individual “blocks” correspond to functions such as representing stimulus features or selecting actions, while task flexibility emerges from how these blocks are combined.Compared to earlier work, the study emphasizes that these shared components can be observed directly in neural activity patterns, particularly in the prefrontal cortex, during task performance. This provides experimental support for the idea that cognitive flexibility relies on the recombination of existing neural elements rather than the creation of entirely new ones.Key Findings and Authors’ Conclusions1. Shared neural activity across tasks According to the authors, the study shows that the brain can rely on shared patterns of neural activity across different tasks. Their analyses indicate that neural representations used to process specific information – such as stimulus color or action direction – can be reused when similar components are required in another task, even if other task features differ.2. Role of the lateral prefrontal cortexThe researchers report that these shared activity patterns were most clearly observed in the lateral prefrontal cortex. When a task required a particular type of information, the corresponding neural component became more prominent, while representations of task-irrelevant information were reduced. This selective engagement and suppression of neural components depended on current task demands.3. Sequential structure of task performanceThe authors describe task performance as a sequential process. First, relevant sensory information was represented in neural activity. This information was then transformed into a motor response. The structure of this sequence depended on the task the animal inferred it was performing.4. Task representations as a control mechanismBased on these findings, the authors conclude that cognitive flexibility may rely on composing behavior from shared neural subspaces rather than creating entirely new representations for each task. In their interpretation, representations of task context act as a control signal that determines which neural components are engaged at a given moment.5. LEGO analogy in public explanationsIn public explanations of the study, this mechanism has been described using a LEGO analogy, where basic cognitive components are compared to building blocks that can be assembled and reassembled in different ways to support different tasks, as summarized by Neuroscience News. This analogy is used as a simplified way to communicate the study’s findings and does not represent terminology used in the original research article.6. Limitations and future directionsThe researchers also emphasize important limitations. The study focused on a small set of related tasks and was conducted in non-human primates. They state that further research is needed to determine how broadly these compositional principles apply across other task types, brain regions, and learning contexts.Key Questions Answered (As summarized by NeuroscienceNews, based on the authors’ findings): Q: What makes the human brain more flexible than AI?A: The brain reuses core cognitive building blocks across many tasks, allowing rapid adaptation.Q: Where are these reusable cognitive blocks located?A: In the prefrontal cortex, which assembles and quiets blocks depending on the task.Q: Why does this matter for learning and behavior?A: Because combining and recombining cognitive components enables quick learning without overwriting older skills.The information in this article is provided for informational purposes only and is not medical advice. For medical advice, please consult your doctor.ReferencesTafazoli, S., Bouchacourt, F.M., Ardalan, A. et al. Building compositional tasks with shared neural subspaces. Nature (2025). https://doi.org/10.1038/s41586-025-09805-2NeuroscienceNews. (2025). Brain Rebuilds New Skills Using “Cognitive LEGO Blocks”.https://neurosciencenews.com/brain-cognitive-blocks-29986/The post Study Shows the Brain Reuses Cognitive Building Blocks to Switch Between Tasks appeared first on CogniFit Blog: Brain Health News.