The human brain is not a single organ, but two separate systems that evolved independently before fusing together, according to groundbreaking new research. … Armed with the knowledge of how hindbrain cells uniquely form, the team has successfully turned human stem cells into becoming functional hindbrain motor neurons in a lab for the first time.
There are brain surgeries where you just chuck out the extra to get to the parts you want to work on, eloquent vs non-eloquent tissue. And epilepsy surgery where they completely disconnect the halves. Recently read a pretty good book on this.
If you skip the first chapter, and then stop once he starts talking about anything other than neuroscience The Immortal Mind is a great overview of this by an extremely talented neurosurgeon who has dog shit views on literally everything else. Still worth it for the good parts but I warned you.