The story of how mapmakers accidentally built bigger hippocampuses is a fascinating blend of neuroscience, cartography, and a bit of serendipity. It all begins with the hippocampus, a small but crucial part of the brain deeply involved in memory formation and spatial navigation. For decades, scientists have studied this seahorse-shaped structure to understand how we remember places and events. Meanwhile, mapmakers—those who create visual representations of space—have been working on ways to chart not just the physical world but also the inner landscapes of the brain.
The accidental enlargement of hippocampuses in maps happened because of the way spatial information is represented and interpreted. Early neuroscientists and cartographers collaborated to create detailed maps of the brain’s regions, including the hippocampus. These maps were intended to help researchers visualize the brain’s complex architecture. However, the methods used to translate three-dimensional brain structures into two-dimensional maps introduced distortions. Just like projecting the round Earth onto a flat map can make Greenland look enormous, mapping the hippocampus onto flat surfaces sometimes made it appear larger than it really is.
This distortion was not merely a technical glitch but also a consequence of the brain’s own spatial coding systems. The hippocampus contains specialized cells—place cells and grid cells—that help animals and humans navigate their environment by creating internal maps. When scientists tried to represent these neural maps visually, they had to simplify and exaggerate certain features to make the patterns clear. This simplification inadvertently “inflated” the hippocampus in the maps, making it look bigger and more prominent.
Another factor contributing to the accidental enlargement was the center-surround inhibition principle in neural processing. This principle means that neurons responding to a particular stimulus suppress the activity of neighboring neurons, sharpening the brain’s focus on important information. When applied to mapping neural activity, this effect created a kind of “halo” around active regions like the hippocampus, visually expanding its boundaries on the map. This phenomenon helped highlight the hippocampus’s role in spatial memory but also made it seem larger than its actual physical size.
The story also ties into the broader history of cartography and diagrammatic thinking. Just as mapmakers have long struggled with representing the Earth’s surface accurately, neuroscientists face similar challenges when charting the brain’s intricate networks. The discovery of grid cells and place cells by researchers like John O’Keefe and the Mosers revolutionized our understanding of spatial navigation, but translating these discoveries into visual maps required creative compromises. These compromises, while necessary for clarity, sometimes led to exaggerated depictions.
Interestingly, this accidental enlargement has had some positive effects. By making the hippocampus appear bigger and more distinct, these maps have drawn attention to its critical functions, inspiring further research and public interest. The visual emphasis helped communicate complex ideas about memory and navigation to a wider audience, bridging gaps between disciplines like neuroscience, psychology, and cartography.
In recent years, advances in imaging technology and computational modeling have allowed scientists to create more accurate, high-resolution maps of the hippocampus and other brain regions. These new maps correct many of the earlier distortions but still honor the legacy of those initial, larger-than-life depictions. They serve as a reminder that all maps—whether of the Earth or the mind—are interpretations shaped by the tools and perspectives of their creators.
So, the tale of how mapmakers accidentally built bigger hippocampuses is a story about the interplay between scientific discovery, visual representation, and the inherent challenges of mapping complex spaces. It shows how mistakes and exaggerations can sometimes lead to deeper understanding and new avenues of exploration, reminding us that maps are not just about accuracy but also about communication and insight.
