Takehara Lab
Research Projects
How the Brain Builds and Uses Knowledge
Memory is not just about storing past experiences—it helps us make better decisions in the future. Instead of keeping memories as isolated snapshots, the brain looks for patterns and relationships across events. This allows us to make predictions and solve new problems, even in unfamiliar situations. Our research explores how this ability is built in the brain, focusing on the medial prefrontal cortex, a region involved in reasoning and decision making. By recording activity from many neurons, we found that groups of brain cells gradually shift to represent what different experiences have in common. These shared patterns become stable “neural codes” that represent general knowledge. Importantly, these codes are actively used: when animals face new situations, the brain reactivates these patterns in real time to guide decisions. More recently, we have developed tools to study how the brain supports more complex reasoning. Using an automated system, we are identifying which brain regions are involved and how their activity predicts performance.
How the Brain Chooses What to Remember
Not everything we experience becomes a lasting memory. The brain is constantly deciding what is important enough to keep, while filtering out less useful details. This selectivity is essential for learning, decision making, and mental well being. Our research explores how the brain makes these choices. While some events stand out naturally—because they are new or emotionally intense—we found that the brain also relies on past experience to guide what gets remembered. In other words, what you already know and expect plays a powerful role in shaping new memories. Our work shows that the medial prefrontal cortex acts like a “gatekeeper” for memory: depending on its activity level, the same experience may either be stored for the long term or quickly forgotten. When something unexpected happens in a familiar situation, this brain region becomes temporarily more responsive, increasing the likelihood that the new information will be remembered. We also study how chemical signals in the brain help control this process. One such signal, called acetylcholine, appears to act as a marker of surprise, helping the brain decide how much to update its internal model of the world when something unexpected occurs.
How the Brain Decides When to Remember
At any moment, the brain has to decide whether to create a new memory or rely on one it already has. This choice depends heavily on context—such as where you are, what just happened, and what you are doing. We study how this decision is controlled by a brain region called the lateral entorhinal cortex. This region acts as a communication hub between different memory systems, and disruptions here are among the earliest signs of Alzheimer’s disease. Our research shows that this region helps the brain represent “situations” by combining information about space, time, and behavior. In doing so, it signals whether something is new enough to learn or familiar enough to recall. When this system breaks down—either in experiments or in conditions that model Alzheimer’s disease—the brain can lose this balance. As a result, familiar experiences may be treated as if they were new, leading to unnecessary or repetitive memory formation. At the same time, communication between brain regions that support memory recall becomes less effective.
Brain Rhythms as a Window into Memory Disorders
Our lab studies how patterns of brain activity help turn new experiences into lasting memories. One key focus is a type of fast brain activity called sharp wave ripples, which occur in the hippocampus, especially during sleep. These brief bursts act like short “windows” when brain cells communicate intensely, strengthening connections and sharing information with other brain regions to help store memories for the long term. We discovered that these events must be precisely coordinated with slower brain rhythms (sleep spindles) for memory to be stored effectively, and identified key brain cells that support this coordination. We also study how this process breaks down in Alzheimer’s disease. We found that amyloid beta disrupts these ripple events, making it harder for the brain to form and update memories.
Resources
AutoTI
Cost-effective, open-source, automated apparatus for testing transitive inference in mice
Original publication in Scientific Reports
Code and design files in GitHub
New Discoveries
Take a look at our recent research, where we investigate how the brain turns experience into knowledge and applies it to solve new problems.
