Editing Excitatory synapse (section)

===Serotonin===
:[[Serotonin]] is an excitatory neurotransmitter that regulates sleep and wakefulness and is found in neurons of the [[Raphe nuclei|raphe]] region of the pons and upper brain stem, which extend into the [[forebrain]].  Serotonin binds a number of receptors, including the 5-HT<sub>3</sub> receptors, which are ligand-gated ion channels that allow the passage of cations in order to depolarize the membrane potential of the postsynaptic neuron that they reside on.<ref name="Neuroscience, 4th ed."/> Levels of serotonin activity that are lower than normal have been linked to a variety of symptoms, especially [[Major depressive disorder|depression]], which is why many [[antidepressant|antidepressant drugs]] act to increase serotonin activity.<ref name="The Human Brain Mind Center">{{cite web |url=http://www.nutramed.com/brain/neurotransmitters_serotonin.htm |title=Neurotransmitter - Serotonin |author=Stephen Gislason |publisher=Brain Mind Center at Alpha Online |year=1995}}</ref>