Researchers play Bach for young crocodiles during an MRI to see how the reptiles' brains react to complex stimuli. By conducting an MRI on crocodiles, researchers made a first-of-its-kind study that sheds light into the brain process of crocodiles and how it might have evolved.
Nile Crocodile MRI
Researchers of a new study conducted a rather unusual test to understand how the brain of young Nile crocodiles might react to various visual and auditory stimuli. Apart from giving them the chance to compare these processes to birds' and mammals', the test also allowed researchers to get a glimpse of the bridge between dinosaurs and birds, as crocodiles are unique creatures that barely changed over millions of years.
In the past, other researchers have used MRI to study mammals and birds but not reptiles as they are cold-blooded creatures, making it difficult to accurately record their blood oxygenation level as it is dependent on body temperature. Further, conducting such a test on crocodiles is also pretty tricky as the creatures could be dangerous to work with.
To push through with their test, researchers of the current study opted to conduct the MRI on young Nile crocodiles that's just about a meter long, and they also ensured that the temperature in the scanner remained constant so as not to alter the results. To be on the safe side, they also bound the young crocodile while scanning.
Interestingly, while the crocodiles were awake during the test because they did not respond to the given anesthetic, researchers observed that they were quite calm inside the machine. In fact, they would just open their eyes once in a while and look around the machine, but remained quiet and calm.
Bach For Crocodiles
Researchers exposed five young crocodiles to simple visual and auditory stimuli by flashing red and green visual cues at varying strengths and intervals, and by playing random chord noises between 1,000 and 3,000 Hz. They also exposed the creatures to complex sounds by playing Bach's Brandenburg Concerto No. 4, which is the same music that was used in scans of other animals.
The scans showed greater brain response in the crocodiles' brain in the presence of music compared to the simple sounds, with different parts of the brain activating in response to the complex stimuli. Interestingly, the observed pattern even runs similar to the previously observed patterns in birds and mammals.
These results suggest that the functional aspects of sensory processing were possibly conserved during the evolution of the sauropsids, the group of land vertebrates which include all existing reptiles and birds, as well as their fossil ancestors. Researchers also consider the possibility that such brain processes may have developed much earlier than previously thought.
Apart from the interesting results of the MRI scan, researchers also believe that their study shows the future possibilities of using MRI technology on creatures that have never been investigated on such a scanner before.
The study is published in the journal Proceedings of the Royal Society B.