A, Low-magnification (4×) Nissl-stained photomicrograph of the brain tissue section containing the medial ventral striatum depicted in A', outlined by the boxed region. A, Low-magnification (4×) Nissl-stained photomicrograph of the brain tissue section containing the medial ventral striatum depicted in A', outlined by the boxed region. The red dashed region outlines the mOT, and the blue dashed region outlines the lOT. A', Nissl-stained photomicrograph depicting the medial portion of the ventral striatum (medial nucleus accumbens and medial olfactory tubercle) in an adjacent section of forebrain depicted in B. The dashed region outlines the mOT. B, Epifluorescent photomicrograph depicting hM4Di infection in the rostral mOT, immunolabeled for the coexpressed reporter mCitrine. The dashed region outlines the mOT. White arrows point to errant infected cell bodies found outside of the mOT, illustrated as colored dots outside of the traced regions in C. B', z-Plane stacked confocal image showing mCitrine+ cell bodies and fibers magnified from the white, boxed region in B. C, Modified schematic from the mouse brain atlas of Franklin and Paxinos (2008) illustrating regions where hM4Di+ and DAPI+ cells were quantified. Different color tracings indicate the extent of bilateral hM4Di infection within three rostral sections of the ventral striatum for each subject (n = 7). Different color dots represent sparse, errant hM4Di+ neurons found outside of the densely infected (traced) region for each subject. Sections are ordered sequentially from anterior (top) to posterior (bottom), with numerical values representing the distance (in millimeters) anterior to bregma for each section. aca, Anterior commissure; AcbC, Acb core; cc, corpus callosum; mfb, medial forebrain bundle. Brett T. DiBenedictis et al. eneuro 2015;2:ENEURO.0078-15.2015 ©2015 by Society for Neuroscience