Fig 1. Experimental methods and histological confirmation of DREADD expression.

a: AAV construct for hM₄Di expression in vivo. The open reading frame of hM₄Di contains a Hemagglutinin (HA)-tag at its 5’ end and a poly-A (PA) tail on its 3’ end. This gene is driven by an ubiquitous pCB promoter. ITR = inverted terminal repeats. Expression of the HA tag thus directly reflects levels of the hM₄Di protein expression. b: hM₄Di expression (green) in dorsal, intermediate, and ventral hippocampus in a representative mouse brain (A3) revealed by immunohistochemistry (see text for details). Image was acquired using an AxioCam HR camera on an Axio Imager Z1 motorized microscope (Zeiss) with a standard Zeiss FITC filter set. c: Fear conditioning protocol: From top row to bottom row- Recent memory test in Context 1(top row), Remote 1 and 2 memory test in Context 1(second row), test in Context N (third row), and Recent memory test in Context NS (bottom row).