It's all made of naughty stuff.
You don't really want to know.
Myelin (myelin oligodendrocyte protein) ...is secreted one other place in your body....your prostate.
i.e. The substance that makes your neurons "fire faster", in another part of your body - it makes sperm "swim faster".
Neurotransmitter proteins...well, half of them also have other names, like "Epidydmis Binding Protein" and "Sperm Secretory Protein #5", etc.
Look it up sometime.
I ain't making this sh-t up.
The basal ganglia - what do they look like to you?
Why do some people have Multiple Sclerosis? Because their immune system thinks they have herpes. In their brain. Think about that. Why would the immune system think your brain had herpes?
Myelin is considered a defining characteristic of the jawed vertebrates (gnathostomes).
Why jawed vertebrates?
Freud knew why.
"The id is like a horse and the ego is the rider"