Its interesting to note that only mammals have neocortex [1] and birds for instance don’t even have cortex [2]. But since birds have sensory perception, cognition and language, and some of them are also very smart [3] [4] [5], it seems that, either sensory perception, cognition, and language are processed also (even mainly) in other parts of the brain, either birds and other animal species have structures equivalent to the cortex and neocortex and we should stop saying that “only mammals have neocortex” [6].
In the meantime, it sounds less wrong, instead of saying “The neocortex is *the* part of the human brain *responsible* for higher-order functions like sensory perception, cognition, and language...”, to say “The neocortex is *a* part of the human brain that *plays a relevant role* in higher-order functions like sensory perception, cognition, and language...”. This is because, if we combine the widely accepted idea that “only mammals have neocortex” with the expression “neocortex is the part of the brain responsible for higher-order functions”, it seems to indicate that individuals without neocortex do not have higher-order functions, which is false, and we would be, perhaps inadvertently, promoting discrimination of non-human animals without neocortex, such as birds or fish.
It’s certainly true that you can’t slice off a neocortex from the rest of the brain and expect it to work properly by itself. The neocortex is especially intimately connected to the thalamus and hippocampus, and so on.
But I don’t think bringing up birds is relevant. Birds don’t have a neocortex, but I think they have other structures that have a similar microcircuitry and are doing similar calculations—see this paper.
You can arrange neurons in different ways without dramatically altering the connectivity diagram (which determines the algorithm). The large-scale arrangement in the mammalian neocortex (six-layered structure) is different than the large-scale arrangement in the bird pallium, even if the two are evolved from the same origin and run essentially the same algorithm using the same types of neurons connected in the same way. (...as far as I know, but I haven’t studied this topic beyond skimming that paper I linked above.)
So why isn’t it called “neocortex” in birds? I assume it’s just because it looks different than the mammalian neocortex. I mean, the people who come up with terminology for naming brain regions, they’re dissecting bird brains and describing how they look to the naked eye and under a microscope. They’re not experts on neuron micro-circuitry. I wouldn’t read too much into it.
I don’t know much about fish brains, but certainly different animals have different brains that do different things. Some absolutely lack “higher-order functions”—e.g. nemotodes. I am comfortable saying that the moral importance of animals is a function F(brain) … but what is that function F? I don’t know. I do agree that F is not going to be a checklist of gross anatomical features (“three points for a neocortex, one point for a basal ganglia...”), but rather it should refer to the information-processing that this brain is engaged in.
I haven’t personally heard anyone suggest that all mammals are all more morally important than all birds because mammals have a neocortex and birds don’t. But if that is a thing people believe, I agree that it’s wrong and we should oppose it.
Its interesting to note that only mammals have neocortex [1] and birds for instance don’t even have cortex [2]. But since birds have sensory perception, cognition and language, and some of them are also very smart [3] [4] [5], it seems that, either sensory perception, cognition, and language are processed also (even mainly) in other parts of the brain, either birds and other animal species have structures equivalent to the cortex and neocortex and we should stop saying that “only mammals have neocortex” [6].
In the meantime, it sounds less wrong, instead of saying “The neocortex is *the* part of the human brain *responsible* for higher-order functions like sensory perception, cognition, and language...”, to say “The neocortex is *a* part of the human brain that *plays a relevant role* in higher-order functions like sensory perception, cognition, and language...”. This is because, if we combine the widely accepted idea that “only mammals have neocortex” with the expression “neocortex is the part of the brain responsible for higher-order functions”, it seems to indicate that individuals without neocortex do not have higher-order functions, which is false, and we would be, perhaps inadvertently, promoting discrimination of non-human animals without neocortex, such as birds or fish.
[1] https://en.wikipedia.org/wiki/Neocortex
[2] https://www.theguardian.com/science/neurophilosophy/2016/jun/15/birds-pack-more-cells-into-their-brains-than-mammals
[3] https://www.gizhub.com/crows-smarter-apes-language
[4] https://www.bbc.com/future/article/20191211-crows-could-be-the-smartest-animal-other-than-primates
[5] http://m.nautil.us/blog/why-neuroscientists-need-to-study-the-crow
[6] https://www.sciencedaily.com/releases/2012/10/121001151953.htm
It’s certainly true that you can’t slice off a neocortex from the rest of the brain and expect it to work properly by itself. The neocortex is especially intimately connected to the thalamus and hippocampus, and so on.
But I don’t think bringing up birds is relevant. Birds don’t have a neocortex, but I think they have other structures that have a similar microcircuitry and are doing similar calculations—see this paper.
You can arrange neurons in different ways without dramatically altering the connectivity diagram (which determines the algorithm). The large-scale arrangement in the mammalian neocortex (six-layered structure) is different than the large-scale arrangement in the bird pallium, even if the two are evolved from the same origin and run essentially the same algorithm using the same types of neurons connected in the same way. (...as far as I know, but I haven’t studied this topic beyond skimming that paper I linked above.)
So why isn’t it called “neocortex” in birds? I assume it’s just because it looks different than the mammalian neocortex. I mean, the people who come up with terminology for naming brain regions, they’re dissecting bird brains and describing how they look to the naked eye and under a microscope. They’re not experts on neuron micro-circuitry. I wouldn’t read too much into it.
I don’t know much about fish brains, but certainly different animals have different brains that do different things. Some absolutely lack “higher-order functions”—e.g. nemotodes. I am comfortable saying that the moral importance of animals is a function F(brain) … but what is that function F? I don’t know. I do agree that F is not going to be a checklist of gross anatomical features (“three points for a neocortex, one point for a basal ganglia...”), but rather it should refer to the information-processing that this brain is engaged in.
I haven’t personally heard anyone suggest that all mammals are all more morally important than all birds because mammals have a neocortex and birds don’t. But if that is a thing people believe, I agree that it’s wrong and we should oppose it.