The neuronal densities in the telencephalon exceed those observed in the cerebral cortex of primates by a factor of 2-8.
This is curious. I wonder if bird brains are also more energy efficient as a result of the greater neuronal densities (since that implies shorter wires). According to Ratio of central nervous system to body metabolism in vertebrates: its constancy and functional basis the metabolism of the brain of Corvus sp (unknown species of genus Corvus, which includes the ravens) is 0.52 cm^3 O2/min whereas the metabolism of the brain of a macaque monkey is 3.4 cm^3 O2/min. Presumably the macaque monkey has more non-cortical neurons which account for some the difference, but this still seems impressive if the Corvus sp and macaque monkey have a similar number of telencephalic/cortical neurons (1.4B for the macaque according to this paper). Unfortunately I can’t find the full paper of the abstract you linked to to check the details.
I wonder if bird brains are also more energy efficient as a result of the greater neuronal densities (since that implies shorter wires).
Yes—that seems to be the point of that poster I found earlier.
From an evolutionary point of view it makes sense—birds are under tremendous optimization pressure for mass efficiency. Hummingbirds are a great example of how far evolution can push flight and weight efficiency.
Primate/human brains also appear to have more density optimization than say elephants or cetaceans, but it is interesting that birds are even so much more density efficient. Presumably there are some other tradeoffs—perhaps the bird brain design is too hot to scale up to large sizes, and uses too much resources, etc.
Unfortunately I can’t find the full paper of the abstract you linked to to check the details.
It was a recent poster—so perhaps it is still a paper in progress? They claim to have ran the defractionator experiments on bird brains, so they should have estimates of the actual neuron counts to back up their general claims, but they didn’t provide those in the abstract. Perhaps the data exists somewhere as an image from the actual presentation. Oh well.
This is curious. I wonder if bird brains are also more energy efficient as a result of the greater neuronal densities (since that implies shorter wires). According to Ratio of central nervous system to body metabolism in vertebrates: its constancy and functional basis the metabolism of the brain of Corvus sp (unknown species of genus Corvus, which includes the ravens) is 0.52 cm^3 O2/min whereas the metabolism of the brain of a macaque monkey is 3.4 cm^3 O2/min. Presumably the macaque monkey has more non-cortical neurons which account for some the difference, but this still seems impressive if the Corvus sp and macaque monkey have a similar number of telencephalic/cortical neurons (1.4B for the macaque according to this paper). Unfortunately I can’t find the full paper of the abstract you linked to to check the details.
Yes—that seems to be the point of that poster I found earlier.
From an evolutionary point of view it makes sense—birds are under tremendous optimization pressure for mass efficiency. Hummingbirds are a great example of how far evolution can push flight and weight efficiency.
Primate/human brains also appear to have more density optimization than say elephants or cetaceans, but it is interesting that birds are even so much more density efficient. Presumably there are some other tradeoffs—perhaps the bird brain design is too hot to scale up to large sizes, and uses too much resources, etc.
It was a recent poster—so perhaps it is still a paper in progress? They claim to have ran the defractionator experiments on bird brains, so they should have estimates of the actual neuron counts to back up their general claims, but they didn’t provide those in the abstract. Perhaps the data exists somewhere as an image from the actual presentation. Oh well.