The researchers' new study found a comparable region in chicken brains that analyzes audio input is constructed similarly to that of mammals, including humans, the university reported in a news release.
For more than 100 years, neuroscientists believed the brains of humans and other mammals differed from the brains of animals such as birds, partially based upon the physical structure of the neocortex, the region of the brain responsible for complex cognitive behaviors, the university said Friday.
"And so ends, perhaps, this claim of mammalian uniqueness," said Harvey J. Karten, a professor at the School of Medicine's Department of Neurosciences and lead author of the study, published in the latest edition of Proceedings of the National Academy of Sciences Online Early Edition.
In their research, the UCSD researchers mapped a region of the chicken brain similar to the mammalian auditory cortex, both of which handle listening duties. The researchers said they found the bird's cortical region has cell formations and microcircuits virtually identical to those in the mammal's cortex.
The findings indicate certain cellular properties of the neocortex aren't unique to mammals and may have evolved from cells and circuits in much more ancient vertebrates, the researchers said.