In Mammals, one of the most physiologically-relevant and studied currents is the M current, named this because it is a current observed in neurons in response to addition of muscarine. The M current is inhibited by various brain peptides and M1 muscarinic acetycholine GPCRS. M currents are recorded from brain tissue are all thought to contain Kv7.3, and one combination that appears to be responsible for making M current in neurons in Kv 7.3 with Kv 7.5. These subunits are preferentially expressed in brain & sympathetic ganglia. Openers active on brain currents limit repetitive firing, and their ability to modulate overactivity in dopaminergic & serotonergic pathways is of therapeutic interest for schizophrenia, drug abuse and anxiety.