In an illuminating study, MIT researchers have revealed that our brains employ cognitive maps for mental navigation just as they do for physical movement through space. This research, conducted by Mehrdad Jazayeri, Sujaya Neupane, and Ila Fiete, sheds light on how the brain’s entorhinal cortex, known for its role in spatial navigation, also supports the mental simulation of experiences, even in the absence of sensory input.
Traditionally, cognitive maps have been associated with physical navigation, where the brain encodes and uses information about environments to guide movement. The hippocampus and entorhinal cortex are well-documented for their roles in this process, creating detailed mental representations of spatial layouts based on sensory input. However, Jazayeri’s team has now demonstrated that these cognitive maps are not limited to spatial contexts but are also active during mental simulations of nonspatial sequences.
In their study, the researchers used a joystick-based navigation task with animals to investigate this phenomenon. Animals were trained to traverse a sequence of images, and researchers monitored neural activity in the entorhinal cortex as the animals performed the task. They discovered that neurons in this region displayed distinctive patterns of activity, which corresponded with the expected timing and order of the images, even when the images were not physically present.
This finding suggests that the entorhinal cortex creates and maintains a mental map of sequences, which can be activated during mental simulations. The results indicated that these cognitive maps are crucial for navigating and recalling sequences of experiences without direct sensory input. This capability of the brain to generate and utilize cognitive maps for mental tasks highlights the complexity and versatility of our cognitive systems.
The study’s breakthrough also involved developing a computational model that mimics the observed brain activity patterns. This model, a continuous attractor model, was adapted to simulate how the brain might reconstruct sensory experiences through learned activity patterns, further elucidating the mechanisms behind mental navigation. The model demonstrated that cognitive maps are not static but dynamically learned and adjusted based on sensory inputs and experiences.
Future research will explore how these cognitive maps function in different scenarios, such as with unevenly spaced landmarks or complex arrangements. Additionally, the researchers aim to investigate how the hippocampus and entorhinal cortex interact during the learning and execution of navigation tasks, providing deeper insights into the brain’s mapping and memory systems.
The implications of this research extend beyond understanding cognitive maps in animals. By revealing the cellular basis of mental simulation, this study offers new perspectives on how we process and remember information, potentially influencing approaches in education, memory enhancement, and the treatment of cognitive disorders.
This research was supported by various institutions, including the Natural Sciences and Engineering Research Council of Canada, the Québec Research Funds, the National Institutes of Health, and the Paul and Lilah Newton Brain Science Award. As MIT continues to push the boundaries of neuroscience, this work represents a significant step toward unraveling the complexities of the human brain’s navigational and memory systems.
