The Unique Layout of Avian Brains:
In the opinion paper titled Why birds are smart, Onur Güntürkün, Roland Pusch, and Jonas Rose argue that the traditional view held by many cognitive neuroscientists that in order for an organism to have complex cognition it must have a large brain and an isocortex is not accurate. The researchers support this claim by analyzing the brains and cognitive abilities of birds such as corvids and parrots. Though these birds have much smaller brains than those of animals like chimpanzees and humans, they still show a level of cognitive abilities similar to that of chimpanzees. The researchers propose that this complex cognition in smaller brains is possible due to multiple factors: a large number of neurons per unit brain volume, a prefrontal cortex-like area, dense dopaminergic innervation of association areas, and dynamic neurophysiological properties for working memory. In addition, birds also have a kind of isocortex that has similar structures to a mammal isocortex, which allows for their large number of neurons. However, birds seem to have a different mechanism for memory storage and retrieval because they lack key elements found in the mammalian sleep cycle for mammalian memory storage. Overall, the writers believe that a mammalian-type isocortex is not necessarily required for complex cognition, and there are different mechanisms which have developed in other organisms that still result in a high level of cognitive abilities.
The Efficiency of Bird Neurons:
In the article titled Bird neurons use three times less glucose than mammalian neurons, Kaya von Eugen and colleagues propose possible theories which may explain why birds use so much less glucose than mammals for neuronal function. The first clear theory is the size difference between avian and mammalian neurons. However, that size difference alone cannot account for the difference in glucose usage. On average, the pigeon brain consumes about 27.29 ± 1.57 μmol glucose per 100 g per min when the animal is awake. Even in proportion to the much larger size of the average mammalian brain, avian brains consume three times less than the amount of glucose mammal brains consume per min. In addition, avian brains contain many more neurons than a mammalian brain of similar size, and they have a relatively high level of intelligence. The researchers believe that the efficiency of birds' neurons may be related to their higher body temperature and/or the unique layout of avian brains, but this hypothesis has not yet been proven.
Making a Connection:
Both of the research pieces investigate the surprising cognitive abilities of birds and how they exhibit some cognitive abilities that are similar to that of mammals with much larger brains. The articles supplement each other by providing explanations behind avian intelligence. In the first paper, Güntürkün and colleagues highlight the unique neural features of bird brains that add to their intelligence: a high density of neurons, a prefrontal cortex-like region (NCL), dense dopaminergic innervation, and dynamic neural activity patterns supporting working memory. The article about Kaya von Eugen's work focuses on the energy efficiency of bird brains, specifically their lower glucose consumption compared to mammals. This finding helps explain how birds can maintain a large number of neurons and complex cognitive functions even with a much smaller brain size. The lower glucose consumption, possibly due to higher body temperature or brain layout, could be another factor contributing to the cognitive abilities observed in birds, as was discussed in the first paper.
Looking to the Future:
As far as future applications for these findings, they both challenge traditional assumptions about the relationship between brain size, structure, and cognitive ability. They offer valuable information about the evolution of intelligence across different species and highlight the importance of considering other factors besides just the size of the brain. This research could further understandings of the many different ways brains can be organized and how they support complex cognitive functions in unique ways.
Cell Press. “Bird Neurons Use Three Times Less Glucose than Mammalian Neurons.” ScienceDaily, 8 Sept. 2022, www.sciencedaily.com/releases/2022/09/220908112439.htm. Accessed 9 Dec. 2024.
Güntürkün, Onur, et al. “Why Birds Are Smart.” Trends in Cognitive Sciences, vol. 28, no. 3, Mar. 2024, pp. 197–209, https://doi.org/10.1016/j.tics.2023.11.002. Accessed 9 Dec. 2024.
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