Brain Anatomy

Does size matter?

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Science  29 Jul 2016:
Vol. 353, Issue 6298, pp. 459-460
DOI: 10.1126/science.353.6298.459-f

Contrary to historical perception, although their brains are small, birds are surprisingly smart. Olkowicz et al. compared neuronal numbers across mammalian and bird species with similar brain mass. They found that parrot and songbird brains have twice as many nerve cells as mammalian brains of equivalent size. Their neurons are more densely packed than those of any mammal, even primates. What is more, corvids (crows, jays, and ravens) and songbirds have an exceptionally high percentage of neurons located in brain structures that are the avian homolog of the neocortex. The extremely high packing density of bird brains leads to short interneuronal distances. This results in high information processing speeds, which might further enhance the cognitive abilities of some species. Intelligence may depend more on the absolute number and connections of neurons than on brain size.

Proc. Nat. Acad. U.S.A. 113, 7255 (2016).

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