Locations of stimulus and recording sites. A: Stimulus locations in CA1/subiculum areas. Numbers on the left represent distance from the bregma. B: Recording sites in the PFC. Solid circles represent the locations of neurons in which LTE was induced by HFS. Triangles represent LTD induced by HFS. Open circles are neurons in which LTD was induced by LFS. The number represents distance from the bregma. M2: secondary motor cortex, Cg1:cingulate cortex area 1, PrL: prelimbic cortex, IL: infralimbic cortex.