Your analogy is not good. The equivalent of hooking up jumper cables would be adding a clump of neurons. A chemical that washes over the entire system is more

Your analogy is not good. The equivalent of hooking up jumper cables would be adding a clump of neurons. A chemical that washes over the entire system is more akin to giving the computer a clean/wash (not with water) when the computer has grime and dirt blocking various connections (/ neural pathways).