premise: Serotonin causes neuromodulation.
hypothesis: Neuromodulation . Major neuromodulators in the central nervous system include dopamine , serotonin , acetylcholine , histamine , and norepinephrine . For this reason , some neurotransmitters are also considered to be neuromodulators , such as serotonin and acetylcholine . Serotonin ( [ ˌsɛrəˈtoʊnᵻn , _ ˌsɪərə - ] ) or 5-hydroxytryptamine ( 5-HT ) is a monoamine neurotransmitter .