Primate-Like Cerebellum Connectivity Makes Parrots Smarter

Extraordinary cerebro-cerebellar circuitry is linked to parrots’ intelligence.

Posted Jul 06, 2018

For the first time, neuroscientists have identified that primate-like connectivity between the cerebellum (Latin for "little brain") and the cerebrum may be linked to superior avian intelligence and complex cognitive abilities in parrots.

What makes this discovery in the animal kingdom especially significant is that gaining a better understanding of how cerebro-cerebellar connectivity works in birds and primates could help us better understand the neural underpinnings of human intelligence.

Cristián Gutiérrez-Ibáñez, Andrew N. Iwaniuk, Douglas R. Wylie (2018) in Scientific Reports/Creative Commons 4.0
Cortico-cerebellar pathways in birds and mammals. In mammals, inputs from the cortex to the cerebellum are routed through the pontine nuclei. In birds, inputs from the telencephalon to the cerebellum are also routed through two nuclei in the base of the pons (medial and lateral pontine nuclei, PM and PL) but also through an additional nucleus in the pretectum, the medial spiriform nuclei (SpM). 
Source: Cristián Gutiérrez-Ibáñez, Andrew N. Iwaniuk, Douglas R. Wylie (2018) in Scientific Reports/Creative Commons 4.0

This paper,” Parrots Have Evolved a Primate-Like Telencephalic-Midbrain-Cerebellar Circuit," was published July 2 in Scientific ReportsCristián Gutiérrez-Ibáñez, professor of psychology at the University of Alberta, was the first author of this paper. For this study, Gutiérrez collaborated with Douglas Wylie, who heads up the neuroscience-based “Bird Brains Lab” with co-author Andrew Iwaniuk of the University of Lethbridge's Canadian Centre for Behavioural Neuroscience (CCBN).

A key finding of this research is that the telencephalon-SpM-cerebellar pathway in parrots may play a very similar role to the cortico-ponto-cerebellar pathway of primates in terms of controlling finely-tuned motor skills and facilitating certain cognitive processes.

For this study, the Canadian team had access to the largest collection of bird brains in the world. After comparing anatomical differences in the brain structure of 98 different bird types, the researchers found that a small brain region that connects the cerebellum to the cerebral cortex in birds (called the "medial spiriform nucleus" or SpM) was much bigger in parrots.

"An area of the brain that plays a major role in primate intelligence is called the pontine nuclei, this 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,” Gutiérrez said in a statement. “In humans and primates, the pontine nuclei are large compared to other mammals. This makes sense given our cognitive abilities."

The SpM region performs the same function in birds as the pontine nuclei region performs in primates, which is to circulate information between the cerebellum and the cerebral cortex of the cerebrum. "This loop between the cortex and the cerebellum is important for the planning and execution of sophisticated behaviours," Doug Wylie said in a statement.

“Independently, parrots have evolved an enlarged area that connects the cortex and the cerebellum, similar to primates,” Gutiérrez said. “This is another fascinating example of convergence between parrots and primates. 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. This could present an excellent way to study how the similar, pontine-based, process occurs in humans," Gutiérrez concluded. "It might give us a way to better understand how our human brains work."

“Whatever the Cerebellum Is Doing, It’s Doing a Lot of It.”

For most people, learning that parrots’ intelligence may be linked to primate-like connectivity between the cerebrum and the cerebellum probably wasn’t a jaw-dropping, “wow!” moment. But, for me, learning this information almost caused me to fall off my chair.

In 2005, my late father, Richard Bergland (1932-2007) and I created a radical new split-brain model we called “up brain-down brain” which put the structural and functional connectivity between the cerebellum and the cerebrum in the spotlight. (For more see, “The Split-Brain: An Ever-Changing Hypothesis.")

Photo and illustration by Christopher Bergland (Circa 2007)
This diagram illustrates the earliest incarnations of the "Bergland Split-Brain Model" and describes various hypothetical contributions of the cerebrum and cerebellum during cerebro-cerebellar interplay. (From p. 81 of The Athlete's Way)
Source: Photo and illustration by Christopher Bergland (Circa 2007)

My dad was a neurosurgeon, neuroscientist, and author of The Fabric of Mind (Viking). Whenever we discussed the inner workings of the brain, my father would chime in, “We don’t know exactly what the cerebellum is doing. But whatever it’s doing, it’s doing a lot of it.

In the early-21st century, there were only a handful of neuroscientists who speculated that the cerebellum was involved in any type of higher-order cognitive processes. My father was one of them. At the time, most experts thought the cerebellum was only responsible for "non-thinking" motor functions such as fine-tuning muscle coordination and orchestrating the precise timing of physical movements. Because my background is in professional sports, the cerebellum was always of particular interest to me. The 'little brain' facilitates what I call "superfluidity" and is central to peak athletic performance.

Unfortunately, when I published our radical “up brain-down brain” model a decade ago in The Athlete's Way: Sweat and the Biology of Bliss (St. Martin's Press), the concept was flat-out rejected by the medical establishment and failed to pique the curiosity of general readers. The book was a flop. That said, I’d like to think dad and I were ahead of our time... Based on the groundswell of cerebellar research lately, I’m optimistic that sometime this century the cerebellum will finally get the full recognition and appreciation it deserves.

After my father's death in 2007, I made a vow that I'd keep my antennae up for any new cerebellar research in honor of his life's work. And, that I'd do my best as a layperson to help advance our understanding of how the cerebellum works and continue to share this information with everyday readers. 

One day back in 2009, with the cerebellum on my mind, I had a Eureka! moment as I was walking home from the gym and bumped into a friend of mine named Maria who is a poet. As we were discussing the possible link between aerobic exercise and creative thinking she said, “Whenever I start moving my arms and legs back and forth on the elliptical trainer, poetry pours out me.”

The moment Maria uttered these words, an image of all four brain hemispheres interacting like a "super-8 infinity loop" flashed into my mind. So, I rushed home and tried to get an artistic representation of these feedforward and feedback loops down on paper, as quickly as I could. This hasty attempt resulted in the colorful chicken scratch displayed in the brain map below. (For more on this see, "Eureka! Deconstructing the Brain Mechanics of "Aha!" Moments.")

Photo and illustration by Christopher Bergland (Circa 2009)
This sketch illustrates an updated version of the original "up brain-down brain," split-brain model that Christopher Bergland created with his father.
Source: Photo and illustration by Christopher Bergland (Circa 2009)

The yellow and green "super 8" with bi-directional arrows in the "bridging the gaps between all four brain hemispheres" illustration above represents feedback and feedforward interplay between various regions of both cerebral hemispheres and both cerebellar hemispheres. As you can see, I colloquially refer to the midbrain as "the bridge" that connects the cerebrum and cerebellum. After reading the latest paper by Gutiérrez-Ibáñez et al., I know that this area is technically called the "pontine nuclei" in mammals and primates.

When I drew the brain map above in 2009, I was unaware of Jeremy Schmahmann’s groundbreaking ataxia-based research on the cerebellum at Harvard Medical School's MGH. In recent years, I've had the good fortune of communicating with Schmahmann on a regular basis and realize now what a cerebellar trailblazer he's been since the late-20th century. (For more see his landmark papers, “The Cerebrocerebellar System" (1997) and "Dysmetria of Thought: Clinical Consequences of Cerebellar Dysfunction on Cognition and Affect." (1998)) 

Because I'm not a neuroscientist, the layout of the rudimentary cerebro-cerebellar map above was primarily inspired by thinking a lot about a possible link between the cerebellum and cognition based on inspiring conversations with my father.

For the past decade, I’ve been on the lookout for empirical evidence and neuroscience-based research that would help me better understand and communicate the meaning of this map, which I drew on a whim. Suffice to say, when I read about the latest research from the “Bird Brains Lab” and saw their illustrations of cortico-cerebellar connectivity in primates and birds, I was over the moon.

We still have a long way to go before we’ll actually know “what the cerebellum is doing.” Thankfully, pioneering research like the new study on a cerebellar connection to parrots' intelligence by Cristián Gutiérrez-Ibáñez, Andrew Iwaniuk, and Douglas Wylie brings us one step closer to solving this riddle.

References

Cristián Gutiérrez-Ibáñez, Andrew N. Iwaniuk, Douglas R. Wylie. "Parrots Have Evolved a Primate-Like Telencephalic-Midbrain-Cerebellar Circuit." Scientific Reports (First published: July 2, 2018) DOI: 10.1038/s41598-018-28301-4

Jeremy D. Schmahmann and Deepak N.Pandyat. "The Cerebrocerebellar System." (1997) International Review of Neurobiology DOI: 10.1016/S0074-7742(08)60346-3

Jeremy D. Schmahmann. "Dysmetria of Thought: Clinical Consequences of Cerebellar Dysfunction on Cognition and Affect." (1998) Trends in Cognitive Sciences DOI: 10.1016/S1364-6613(98)01218-2

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