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.
What does a koala's brain look like? First detailed MRI map reveals its unique marsupial structure.
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The first high-resolution MRI map of a koala's brain provides a crucial baseline for future research and veterinary care of this endangered marsupial. What this means for you:
The first high-resolution MRI map of a koala's brain provides a crucial baseline for future research and veterinary care of this endangered marsupial. View Original Abstract ↓
IntroductionAustralia’s native fauna is unique through millions of years of isolated evolution resulting in a significant divergence of marsupial brain anatomy, and thus neural pathways, from eutherian mammals. This study provides a morphometric description of a mature female koala (Phascolarctos cinereus) through segmentation of high-resolution magnetic resonance images. As the availability of brain specimens of the endangered koala is scarce, brain segmentation has been performed on a single specimen.MethodsThe brain of a naturally deceased koala was removed and fixed in 10% neutral buffered formaldehyde (pH 7.0). The MRI was acquired on a 9.4 T Bruker Biospec MR system with Paravision 7.0 software, using a 3D multigradient echo sequence, with TR/TE = 70 msec/ (8 echoes 4–32 msec), a field of view = 7.0 × 6.4 × 4.0 cm3. AMIRA post image processing software was used to create three-dimensional volume reconstruction of different brain structures, allowing for the calculation of their volumes.ResultsThe koala brain is lissencephalic and has a volume of 15720.98 mm3. It was found that the olfactory bulbs of the koala were 418 mm3 or 2.66% of the total brain volume (tbv). The cerebral hemispheres were 9336.92 mm3 (59.39% of the tbv). The interhemispheric connections were 148 mm3 (0.94% of tbv). The combined volume of the anterior commissure and fasciculus aberrans, which is specific to marsupials, has also been labeled and segmented. The ventricular system was 172 mm3 (1.09% of tbv). The brainstem was 1874 mm3 (11.92% of tbv). The cerebellum was 2304.69 mm3 (14.66% of tbv).ConclusionThis study can be used as a basis for clinical imaging of koalas and as baseline data for future research into brain development of koalas and other marsupials.