A. Representative images from a single rhesus monkey showing binding of the selective DAT radiotracer [18F]-FECNT. Images are displayed in transverse (left), sagittal (top right), and coronal (bottom right) orientations. All images are oriented in radiological convention. Binding is highly localized to striatal areas. B. Representative images from a single rhesus monkey showing binding of the selective SERT radiotracer [18F]-m-ZIENT. Images are displayed in transverse (left), sagittal (top right), and coronal (bottom right) orientations. All images are oriented in radiological convention. Binding is diffuse and extends through cortical and sub-cortical areas. However, the highest levels of binding are localized to the raphe nucleus.