You don't have to have a degree in neuroscience to be aware of the fact that we aren't even close to understanding how human brain works when it comes to high-level process such as sentience.
First off we understand a lot about the human brain, but that doesn't matter because no one is arguing that we understand the totality of the human brain, instead what is being argued is: The human brain is as simple as an LLM and thus LLMs are sentient, can reason, and can know facts.
It should be an HN rule that in order to type out variations of this sentence you have to also prove you have a degree in neuroscience.