Introduction
Forebrain Inputs to PAG
In the 1980s and 1990s, tract-tracing studies from a number of laboratories (e.g., Beitz 1982; Shipley et al. 1991) revealed an important feature of the PAG; afferent inputs to the PAG arise from a staggering number of cortical and subcortical forebrain sites. These inputs to the PAG are much heavier than previously suspected and terminate with a remarkable degree of topographic specificity. Major identified forebrain afferents to the PAG include the medial prefrontal cortex (MPF), the medial preoptic area (MPO), the central and medial nuclei of the amygdala (CeA, MeA), the ventromedial hypothalamus (VMH), and the paraventricular nucleus of the hypothalamus (PVN).
Definition
The midbrain periaqueductal gray (PAG) and its descending projections to the rostral ventromedial medulla (RVM) comprise a critical descending neuroanatomical pathway modulating pain and analgesia. The PAG projects heavily and directly to the RVM, which in turn projects to the do...
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Acknowledgement
The authors would like to recognize the contributions of Dr. Matthew Ennis and Xijing Zhang on the first edition of this chapter.
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Loyd, D.R., Murphy, A.Z. (2013). Forebrain Modulation of the Periaqueductal Gray and Its Role in Pain. In: Gebhart, G.F., Schmidt, R.F. (eds) Encyclopedia of Pain. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-28753-4_1534
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