>>14345676The important part of the brain is the basal ganglia. The nerves leaving it are axons stemming from the neurons. Head transplants haven been done with animals but resulted in paralysis and death by organ failure and infection days later. The most difficult part of neurology are biochemical and electrical synapses. It's already complicated enough, but synapses act on potentials not external properties so they are impossible to externally measure. Two neurons can be in the same external state but completely different because you can't tell their internal potentials. They could be doing nothing or holding back everything.
Neuron transplants have worked in animals. That's your best hope with neurology. Transplant an organ all the way up to the neurons. You will need to dump them into a ventricle in a brain and hope they absorb into ISF. You will probably go through a ton.