Central mechanisms of vomiting.

Nausea and vomiting (emesis) occur under a variety of conditions in response to activation of one or more emetic triggers. The act of vomiting is coordinated by neuronal circuitry located in the brain stem between the obex and the retrofacial nucleus, including the region extending from the nucleus of the solitary tract through the lateral tegmental field of the reticular formation to the ventrolateral medulla. The area postrema, medullary midline, and certain higher brain centers are also important for vomiting. The sensation of nausea is thought to involve the cerebral cortex. The most effective near-term treatment for combating nausea and vomiting associated with cyclic vomiting syndrome may come from experimental drugs (NK-1 receptor antagonists, 5-HT1A receptor agonists) or P6 acustimulation, which have been shown to combat nausea and vomiting in response to a broad spectrum of emetic challenges and thus presumably act on central emetic mechanisms.