Alberta neuroscientists identify what makes parrots not so bird-brained
Brains of the tropical birds wired differently than avian relatives, study finds
Being called a bird-brain may not be so insulting after all, suggests a new University of Alberta study.
Neuroscientists have discovered that parrots, remarkably intelligent birds, share neural circuitry similar to primates.
They found in parrots, a certain part of the brain called the medial spiriform nucleus (SpM) is overdeveloped.
Compared with other major avian groups like songbirds, waterfowl and owls — only parrots have the universally large neural circuit.
"The SpM is very large in parrots. It's actually two to five times larger in parrots than in other birds, like chickens," said Cristián Gutiérrez-Ibáñez, one of the authors of an article titled Parrots have evolved a primate-like telencephalic-midbrain-cerebellar circuit, published this week on the Nature magazine website.
The structure gives these colourful tropical birds the ability solve complex problems and exhibit more sophisticated behaviour than most of their fellow bird brains, said Gutiérrez-Ibáñez, a postdoctoral fellow in the department of psychology.
"Some parrots can use tools, they're also good at solving problems, and this area of the brain is involved in this kind of thing," he said.
Using samples from 98 specimens of bird brains at the University of Lethbridge, in Alberta, one of the largest collection of avian brains in the world, researchers set out to map the differences between bird and primate brains by dissecting everything from chickens to hummingbirds.
What they found provides insight into the basis of human intelligence and the evolution of the primate brain, Gutiérrez-Ibáñez said.
In humans and primates, an area of the brain that plays a major role in intelligence is called the pontine nuclei.
The structure transfers information between the two largest areas of the brain, the cortex and cerebellum, which allows for higher-order processing and more sophisticated behaviour.
In humans and primates, the structure is large compared to other mammals.
"They connect the two main areas of the brain," Gutiérrez-Ibáñez said in an interview with CBC Edmonton's Radio Active.
"This is like a huge highway that is travelled, sending information between these two main areas. We wanted to know if birds and intelligent birds also had a large pontine."
The more we look at the brains, the more similarities we see.- Cristián Gutiérrez-Ibáñez
Instead, researchers discovered that even the most intelligent birds have very small pontine nuclei and instead rely on the medial spiriform nucleus.
Although located in a different part of the brain, the medial spiriform nucleus performs the same functions as the pontine nuclei, circulating information between the cortex and the cerebellum.
"Independently, parrots have evolved an enlarged area that connects the cortex and the cerebellum, similar to primates," Gutiérrez-Ibáñez said.
"This is another fascinating example of convergence between parrots and primates," he said. "It starts with sophisticated behaviours, like tool use and self-awareness, and can also be seen in the brain.
"The more we look at the brains, the more similarities we see."