Fig. 8.

The redefined disinhibition model for the opioid analgesic circuitry in the PAG. (A and B) The disinhibition model in the PAG was proposed by Basbaum and Fields in 1984 (A) and Jacquet in 1988 (B). (C) The redefined disinhibition model proposed here in wild-type (Left) and α1G^−/− mice (Right); it was reproduced in PAG-specific α1G-knockdown mice. •, GABAergic neuron; ○, non-GABAergic neuron; ▲, inhibitory; △, excitatory function; ↑, flow of chemicals; ⇓, the excitatory transmission pathways of the PAG-RVM projection neurons. The thickness of the line indicates relative activity of the individual transmission pathway.