Researchers at the Howard Hughes Medical Institute have shown that mice can engage in imaginative thinking. In experiments, mice demonstrated the ability to picture themselves walking to a location or moving objects to a target site, a finding reported in the journal Science.
Similar to humans, when rats encounter new environments and items, neural activity in the hippocampus—a brain region linked to spatial memory—becomes active. This part of the brain creates internal maps of the world and helps store memories of past events while guiding imagined futures. Before this work, it was not clear whether animals could consciously control this hippocampal function to steer imagined outcomes.
Over several years, the researchers built a brain–machine system that allowed real-time monitoring of neural signals in the mice. In the final setup, a mouse ran on a moving ball inside a dome. A virtual space filled with objects appeared on surrounding walls. With the brain–machine interface, scientists translated the brain signals into a “thought dictionary” that decoded how the mouse represented objects and locations in the virtual world. The animal received water rewards when it reached designated spots or interacted with objects in the virtual space, reinforcing the association between thought, action, and reward.
In a pivotal moment, the treadmill was turned off. The mouse could no longer move through physical action alone, so it had to rely on its own thoughts. The hippocampal activity observed during this phase matched patterns seen when the mouse was moving, suggesting that the animal often imagines reaching a goal where a reward awaits. When the mouse was held stationary within the virtual reality scene, it still appeared to imagine guiding an object toward a target, thereby shaping hippocampal activity without any body movement. The animal sustained this hippocampal pattern while holding a mental image in a specific location for several seconds, a timespan that resembles how people briefly relive memories or conjure new scenarios.
Chongxi Lai, the first author of the work, described the core finding: the mouse can activate representations of places in its environment without physically moving. Even with a still body, its spatial thoughts can travel far across the imagined landscape. This insight adds a new dimension to our understanding of animal cognition and the neural basis of imagination, hinting at shared mechanisms across species for planning, memory, and future planning.
The study’s implications extend beyond basic science, offering a window into how memory and foresight are encoded in the brain. By linking neural activity to deliberately imagined spatial goals, the research sheds light on how internal simulations can guide behavior in the absence of direct experience. The work also prompts further questions about how such internal representations develop, how they influence decision making, and what this means for disorders that affect memory and imagination.
Overall, the findings illustrate that the hippocampus serves not only as a repository of past experiences but also as a dynamic generator of imagined futures. These discoveries contribute to a growing field that examines how animals, including humans, navigate complex environments through mental imagery, plans, and expectations rather than through motion alone.