They are deactivated in the body by the enzymes known as monoamine oxidases which clip off the amine group.Monoaminergic systems, i.e., the networks of neurons that use monoamine neurotransmitters, are involved in the regulation of processes such as emotion, arousal, and certain types of memory.[1] Drugs used to increase or reduce the effect of monoamine neurotransmitters are used to treat patients with psychiatric and neurological disorders, including depression, anxiety, schizophrenia and Parkinson's disease.[citation needed] After release into the synaptic cleft, monoamine neurotransmitter action is ended by reuptake into the presynaptic terminal.[12][13] A recent computational investigation of genetic origins shows that the earliest development of monoamines occurred 650 million years ago and that the appearance of these chemicals, necessary for active or participatory awareness and engagement with the environment, coincides with the emergence of bilaterian or “mirror” body in the midst of (or perhaps in some sense catalytic of?)