What does a koala's brain look like? First detailed MRI map reveals its unique marsupial structure.

Imagine trying to understand a patient's brain without ever having seen a normal one. That's the challenge for scientists and veterinarians studying koalas, whose unique marsupial brains have never been fully mapped. Now, for the first time, researchers have created a detailed 3D picture of a koala's brain using high-resolution MRI scans from a single, naturally deceased female koala. They found the koala's brain is smooth-surfaced and has a total volume of about 15,720 cubic millimeters. The breakdown shows the cerebral hemispheres make up about 59% of the brain, the cerebellum about 15%, and the brainstem about 12%. The olfactory bulbs, important for smell, are about 2.7% of the total. The team also identified and measured a specific bundle of nerve fibers found only in marsupials. This detailed map is more than just an anatomical curiosity. Because koalas are endangered and brain specimens are scarce, this single scan provides a vital reference point. It can serve as a baseline for future studies on marsupial brain development and, importantly, as a guide for veterinarians interpreting clinical brain scans of sick or injured koalas in the wild.