Fig. 5. Influence of in vivo optogenetic inhibition of glutamatergic inputs from the BLA to the PrL on conditioned context–induced increase in the expression of Arc in the BLA in morphine withdrawal mice.

(A) Diagram of virus injection site in the BLA and optical fiber implantation site in the PrL. (B) Arc-positive neurons in the BLA in light OFF and light ON groups (red-colored). Scale bars, 100 μm. BLA regions enclosed by white boxes were shown in a higher magnification in upper right square images. Scale bars, 20 μm. (C) Average Arc-positive neurons/mm² in the BLA in light OFF and light ON groups (n = 6 mice in each group; unpaired t test, **P < 0.01). Data are means ± SEM.