**3.6 Function of nAChRs**

Studies from receptor subunit knockout mice have shown that brain nAChRs are not essential for survival or for the execution of basic behaviors. They are, however, critical for control of several complex behaviors and maintenance of mental health. Modulation of presynaptic nAChRs and, less frequently, postsynaptic nAChRs is responsible for large number of behaviors and brain functions including locomotion, nociception, anxiety, learning and memory, as well as behaviors associated with drug abuse and mental illness. Moreover, stimulation of presynaptic nAChRs receptors promotes neurotransmitter release including dopamine (DA), norepinephrine (NE), serotonin (5HT), glutamate, GABA and ACh.
