The amygdala and ventral portion of the periaqueductal gray (vPAG) are crucial for the expression of the contextual freezing behavior. However, it is still unclear whether the amygdala also plays a role in defensive behaviors induced by electrical stimulation of the dorsal periaqueductal gray (dPAG). In the present study, rats were implanted with electrodes into dPAG for determination of the th...

Previous reports indicated that ventrolateral periaqueductal gray (vlPAG) plays a role in the expression of freezing behavior whereas dorsolateral periaqueductal gray (dlPAG) is involved on both freezing and active forms of defensive behaviors. In order to evaluate the role of each of these areas in the occurrence of defensive reactions, rats were electrically stimulated either in the dlPAG or ...

AIM To study the changes of monoamines in ventrolatoral periaqueductal gray of rat brain before and after electroacupuncture (EA) analgesia (EAA) was enhanced by fenfluramine (Fen), a 5-hydroxytryptamine (5-HT) releaser. METHODS Monoamines were collected by in vivo microdialysis and measured by HPLC connected with electrochemical detector. RESULTS The level of norepinephrine (Nor) after EA ...

Hemington KS, Coulombe MA. The periaqueductal gray and descending pain modulation: why should we study them and what role do they play in chronic pain? J Neurophysiol 114: 2080–2083, 2015. First published February 11, 2015; doi:10.1152/jn.00998.2014.—In this Neuro Forum we discuss the significance of a recent study by Yu et al. (Neuroimage Clin 6: 100–108, 2014). The authors examined functional...