Friday, June 08, 2007

Foreigner and the Area Postrema

The area postrema (Miller & Leslie, 1994) is structure #9 in the figure below.



It has come to my attention that the prior post can induce Conditioned Blog Aversion (CBA).
The area postrema (AP) has been implicated as a chemoreceptor trigger zone for vomiting (emesis) for over 40 years. The AP is located on the dorsal surface of the medulla oblongata at the caudal end of the fourth ventricle. It is one of the so-called circumventricular organs that serve as an interface between the brain parenchyma and the cerebrospinal fluid (CSF)-containing ventricles. The AP lacks a specific blood-brain diffusion barrier to large polar molecules (i.e., a "blood-brain barrier") and is thus anatomically positioned to detect emetic toxins in the blood as well as in the CSF.
CBA is associated with nausea in most readers. However, CBA can induce vomiting in highly sensitive individuals. In an effort to map the neural circuitry of the highly-sensitive variant of CBA, The Neurocritic perused two classic articles on vomiting (Grelot & Miller, 1994; Miller & Leslie, 1994).

from Grelot & Miller (1994)

In general, it appears that CBA falls under the category of Psychogenic Vomiting. Hence, the area postrema is not involved (unless listening to Foreigner, or even the act of imagining listening to Foreigner, results in the release of an emetic substance into the bloodstream). Instead, "higher centers" (i.e., cerebral cortex, limbic system) are likely involved in the highly-sensitive variant of CBA.

So there we have it: "for the first time, researchers have identified neural circuits responsible for Conditioned Blog Aversion (CBA)".

References

Grelot L, Miller AD (1994). Vomiting - Its Ins and Outs. News Physiol Sci 9:142-147.

Miller AD, Leslie RA (1994). The Area Postrema and Vomiting. Frontiers in Neuroendocrinology 15:301-320.


Brainstem credit: Atlas of the brain
Authors: Agnieszka Andrzejczak, Paweł Kreczmański, Jacek Kunicki, Magdalena Leleń
Edited by Bogdan Ciszek, MD.PhD.

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