In a strange study that was recently published in The Journal of Neuroscience, 40 alligators were given ketamine and set up with headphones in order to gather information about what a dinosaur’s hearing could have been like. Alligators were chosen because they are an ancestor of the dinosaurs and have very similar DNA.
The experiment was conducted by Lutz Kettler of the Technische Universität München and Catherine Carr of the University of Maryland. The researchers said that the intent of the study was to learn more about the neural maps of alligators.
“Birds are dinosaurs and alligators are their closest living relatives. Features shared by both groups might reasonably be inferred to have been found in extinct dinosaurs so we assume dinosaurs could localize sound,” Carr told Motherboard.
Researchers measured interaural time difference (IDT), which is essentially the difference in time that it takes a single sound to get to each ear. In the experiment, the alligators were sedated with ketamine and set up with a pair of earbuds along with electrodes that measured their auditory neural responses.
“We used both tones that the alligator could hear well (about 200 to 2000 Hz) and noise. We selected the tones and noise to provide naturalistic stimuli,” Carr explained.
The study found that alligators have an auditory response that is very similar to birds, and they are able to locate sounds with similar neural mapping. Researchers also discovered that the size of the creature did not affect the brain’s ability to process sound, which means that large dinosaurs probably had similar functioning systems.
“One important thing we learn from alligators is that head size does not matter in how their brain encodes sound direction,” Kettler said.
According to the study:
“We show that alligators form maps of ITD very similar to birds, suggesting that their common archosaur ancestor reached a stable coding solution different from mammals. Mammals and diapsids evolved tympanic hearing independently, and local optima can be reached in evolution that are not considered by global optimal coding models. Thus, the presence of ITD maps in the brain stem may reflect a local optimum in evolutionary development. Our results underline the importance of comparative animal studies and show that optimal models must be viewed in the light of evolutionary processes.”
Ketamine is a strong sedative and dissociative that has been used in the veterinary and medical fields since the 1960s, but it has also been known as a club drug for nearly just as long. Numerous studies in recent years have shown that ketamine can be a good treatment option for major depression.
As The Mind Unleashed reported earlier this month, the US Food and Drug Administration (FDA) recently announced the approval of a ketamine-based nasal spray for treating depression.
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