Dopamine is responsible for desire for action.
Cannabinoids is responsible for desire of pain avoidance.
Serotonin is responsible for desire to do the same thing as what everyone does.
Oxytocin is responsible for desire to bring up something to be related to yourselves.
The real nature of desire is a neurotransmitter.
Neurotransmitters responsible for libido is not yet known.
I assume the neurotransmitter that is responsible for libido A.
It has been found that the neurotransmitter is an excitatory thing or inhibitory thing.
When serotonin is released the transmission of A is suppressed for serotonin is an inhibitory thing. A is also inhibitory.
It seems serotonin is reduced when you are with the lover. It is because transmission of the serotonin is
suppressed when A is released.
Dopamine is excitability, but the dopamine some people have is inhibitory.
A character of persons whose dopamine is inhibitory is referred to as phlegmatic temperament.
It has been known that though cannabinoids in adults are the excitement,those in children are suppressive.
It seems that though oxytocin in humans is excitability, that in animals is inhibitory.
Therefore though ethical concern exists, it is possible to change the animal's brain to human brain if
it is possible to change oxytocin in animals from the inhibitory to the excitability.
It seems that Cl- ions are involved in the inhibitory and
Na+ ions are involved in the excitability. So it may be possible by the operation around that.
References:
1)プロが教える脳のすべてがわかる本 岩田誠 監修 ナツメ社 2011年