Scientists gave alligators ketamine for study on hearing
Scientists gave alligators ketamine and headphones.
The study, published in The Journal of Neuroscience was designed to learn about the neural maps alligators generate to locate noises in their habitats, focusing specifically on interaural time difference (ITD), which is the gap in arrival time of a sound to each ear.
Catherine Carr, a biologist at the University of Maryland and Lutz Kettler, a neuroscientist at the Technische Universität München, study how ITD help animals like birds or reptiles locate noises.
Because alligators, birds and dinosaurs are descendants of archosaurs, a lineage from the Triassic Period, the results of the study give insight on the auditory systems of dinosaurs.
“Birds are dinosaurs and alligators are their closest living relatives,” Carr told Motherboard in an email. “Features shared by both groups might reasonably be inferred to have been found in extinct dinosaurs so we assume dinosaurs could localize sound.”
Size doesn’t matter
The team dosed 40 American alligators with ketamine and dexmedetomidine to sedate them. Once they were sedated, Yuin PK2 earbuds fitted with horns were placed in their earlids and electrodes were placed on their heads to record the auditory neural responses to sounds played through the headphones.
“We used both tones that the alligator could hear well (about 200 to 2000 Hz) and noise,” Carr said. “We selected the tones and noise to provide naturalistic stimuli.”
The study revealed that alligators and birds locate sounds using similar neural mapping despite the vast differences in their brain anatomies.
“One important thing we learn from alligators is that head size does not matter in how their brain encodes sound direction,” Kettler said.
This means that dinosaurs such as Tyrannosaurus rex were likely using similar auditory mechanisms as birds and alligators to locate sounds.
Scientists gave alligators ketamine and headphones to better understand dinosaur hearing.