A team of researchers recently decided to put an adult Nile crocodile into an MRI scanner. They wanted to see how the brain of the reptile reacts to complex sounds like classical music. The crocodiles are among the most important reptiles in the world. In Africa, Asia, Australia, and America, they are the largest found reptiles. There are nearly 13 species of the crocodiles and the smallest of them grows to 5.6 feet, while the largest can be nearly 20 feet in length.
These are some of the oldest animals found on earth. The order Crocodilia started existing over 100 million years ago in the Mesozoic era and thrived to reach the top of the food chain. According to the researchers, the crocs lived so long because they changed very little in 200 million years. Felix Strockens, researchers team lead from the department of Biophysiology at Ruhu-Universitat Bochum (RUB) said, “Analyses of crocodile brains thus provide deep insights into the evolution of the nervous system in mammals and may help us understand at which point certain brain structures and behaviors associated therewith were formed.”
The researchers on the team were from Iran, South Africa, France, and Germany. All of the team members worked hard to get accurate readings from a huge crocodile subject. The researchers also opted for a functional MRI which is often used in clinical research and diagnostics. fMRIs note even the slightest changes that occur during the brain activity. The data obtained from a fMRI is then analyzed to see what happens in a particular area of the brain in certain periods. This was the first time a large predator and a cold-blooded animal was the subject of a fMRI.
Mehdi Behroozi, the research team member, said, “In the first step, we had to overcome a number of technical obstacles. For example, we had to adjust the scanner to the crocodile’s physiology, which differs massively from that of mammals in several aspects.” The crocodile was able to easily ruin the study, however, it didn’t fight the fMRI and the research went smoothly. Strockens said in an interview, “Fortunately they seemed to like the scanner tube and did not move at all, which would have ruined our study. We had to be very careful since an angry crocodile could have easily damaged the scanner or injured us—even when they are only one year old, they have pretty strong jaw and tail muscles. But everything went fine and neither we nor the animals got injured.”
When the croc went safely inside the machine, the researchers exposed it to classical music of composer Johann Sebastian Bach. When the animal was listening to Bach, the researchers measured how the brain activity of the reptile was changing while listening to more complex stimuli like classical music instead of simple sounds of nature. The research found that crocodiles have a similar pattern to mammals and birds in their responses to complex noises. Team also found that the fundamental processing mechanism for such sounds come from a very early evolutionary stage since mostly vertebrates have the almost same reaction. These findings will help scientists further understand why Crocs behave the way they do!