Our brains are the product of millions of years of evolution. Scientists would very much like to know how some of the most ancient brains functioned and evolved over time, but that’s obviously not possible, owing to the complete lack of primordial brains to work with. As a good consolation prize, however, scientists can work with crocodiles—an animal that originated more than 200 million years ago, barely changing over the eons. Accordingly, scientists can study crocodiles to understand at which point certain brain structures and behaviors first emerged.
The point of the new study was to determine how the crocodilian brain might respond to complex sounds, and to see how the resulting brain patterns might compare to those observed in mammals and birds. The scientists were hoping to identify precursor brain structures and functions that allow for the processing of complex sights and sounds.
To observe how complex visual and auditory stimulation triggers activity in the reptilian brain, a team led by Felix Ströckens from the Department of Biopsychology at Ruhr University Bochum set about the task of scanning Nile crocodile (Crocodylus niloticus) brains using a functional MRI (fMRI) scanner. These devices are typically used in diagnostic and research settings, and even for studying mammals such as dogs, but this is the first time a cold-blooded animal has been analyzed in such a machine. The results of the new study now appear in the science journal Proceedings of the Royal Society B. (Full Story)
I believe the best summary of the results is “Crocs like Bach.”
For the experiment, the researchers exposed five juvenile crocodiles to various visual and auditory stimuli. The visual cues consisted of flashing red and green lights, which flickered on and off at changing strengths and intervals. Simple auditory cues involved random chord noises between 1,000 Hz and 3,000 Hz. For the complex sounds, the researchers played a part of Johann Sebastian Bach’s Brandenburg Concerto No. 4 (which was used previously in other animal studies, thus providing a good baseline).
Results showed that different areas of the crocodilian brain activated in the presence of complex sounds compared to basic noises. And in fact, the patterns observed resembled those seen in mammals and birds exposed to music. These observations suggest that the structural and functional aspects of sensory processing are present in the reptilian brain, and that these abilities were preserved and passed down the evolutionary family tree (assuming that modern crocodiles share similar brain structures as their ancestors). It’s a fascinating result, said Ströckens, since crocs are a relatively ancient group of species. “Thus it could be that these processing principals evolved much earlier than we thought before,” he said.
What Scientists Saw When They Put a Crocodile in an MRI Scanner and Played Classical Music
Organized Chaos 