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. Author manuscript; available in PMC: 2010 Apr 1.
Published in final edited form as: J Pain. 2009 Feb 23;10(4):426–435. doi: 10.1016/j.jpain.2008.10.011

Figure 1.

Figure 1

The effects of muscimol (50 ng or 100 ng) administered into ventrolateral periaqueductal gray (vPAG) on increases in response thresholds generated by the bilateral injection of morphine (5 μg/side) into nucleus parafascicularis (nPf). Caption next to each graph symbol in the legend indicates drug treatment in vPAG and nPf (saline = sal, mrp = morphine, mus = muscimol). Asterisks indicate significant increase in response thresholds when compared to following administration of saline into vPAG and saline into nPf (sal + sal). Pound signs indicate significant reduction in response thresholds when compared to following administration of saline into vPAG and morphine into nPf (sal + mrp). VAD = vocalization after discharge, VDS = vocalization during shock, SMR = spinal motor reflex (tail flick and hindlimb movements).