Anatomical Atlas of the Baboon's Brain in the Orbito-meatal Plane Used in Experimental Positron Emission Tomography

An anatomical atlas has been constructed of the brain of the baboon (Papio papio) in the orbito-meatal plane (OM-plane) which is frequently used in experimental positron emission tomography (PET) investigations. The atlas comprises 12 photographic reproductions of histological brain sections separated by 2.5 mm intervals, and covers telencephalic to pontine brain stem levels. The anatomical atlas was used in analysis of some PET scan images obtained after administration of either a benzodiazepine (BZ) antagonist, (11C)-Ro 15-1788, or a dopamine D2 receptor antagonist, (76Br)-bromospiperone. Since PET camera detects radiation emitted from a slice of tissue of 15 mm thickness, each PET image corresponds to the tissue represented on six levels of the anatomical atlas. In optimal conditions, the PET image shows a pattern of receptor labelling reminiscent of anatomical structures in the atlas. Sometimes, however, the superimposition of different labelled structures yields a PET image which lacks any apparent resemblance with individual anatomical structures. In these cases, the analysis of the PET scan must rely on the anatomical atlas, as well as available data on the distribution of specific binding sites.